Understanding/Getting symbol type?

Understanding/Getting symbol type? - c#

public void SomeMethod(string sampleString)
{ var helloworld = sampleString; }
Is it possible to determine if a particular symbol is a local variable, class field or method's parameter? e.g. if I call a FindSymbolAtPosition on the sampleString, will i be able to tell that the sampleString symbol is a method's parameter or variable?
EDIT: the requirement is that it must work from coding-time, for my static code analysis tool that im building with roslyn

You can't get it directly via properties, because in var helloworld = sampleString;, the statement has no context that if sampleString is a parameter or not. But you can get it from the method's context like this:
static bool IsParameter(IdentifierNameSyntax name)
{
SyntaxNode node = name;
while (node != null && !(node is MethodDeclarationSyntax))
{
node = node.Parent;
}
var method = node as MethodDeclarationSyntax;
if (method != null)
{
return method
.ParameterList
.Parameters
.Any(p => p.Identifier.Text.Equals(name.Identifier.Text));
}
return false;
}
Using .Parent to get the method context of the variable, and check if any parameter in .ParameterList matches the identifier.
UPDATE Code to prove it's working:
SyntaxTree tree = CSharpSyntaxTree.ParseText(
#"using System;
using System.Collections;
using System.Linq;
using System.Text;
namespace HelloWorld
{
class Program
{
static void Main(string i)
{
var j = ""1"";
var k = i + j;
}
}
}");
var root = (CompilationUnitSyntax)tree.GetRoot();
var ns = root.Members[0] as NamespaceDeclarationSyntax;
var cls = ns.Members[0] as ClassDeclarationSyntax;
var method = cls.Members[0] as MethodDeclarationSyntax;
var statement = method.Body.Statements[1] as LocalDeclarationStatementSyntax;
var variable = statement.Declaration.Variables[0];
var binary = variable.Initializer.Value as BinaryExpressionSyntax;
var vari = binary.Left as IdentifierNameSyntax;
var varj = binary.Right as IdentifierNameSyntax;
Console.WriteLine(IsParameter(vari)); //True
Console.WriteLine(IsParameter(varj)); //False
EDIT Base on #JeroenVannevel's comment, we can use SemanticModel.GetSymbolInfo.
var compilation = CSharpCompilation.Create("test", new[] { tree });
var semanticModel = compilation.GetSemanticModel(tree, true);
var symboli = semanticModel.GetSymbolInfo(vari);
var symbolj = semanticModel.GetSymbolInfo(varj);
//check symboli.Symbol.OriginalDefinition.Kind == SymbolKind.Parameter

Its wrong to compare identifiers by syntax or by text, imagine if the IdentifierNameSyntax is the name of MemberAccessExpressionSyntax and has the same identifier as a parameter, then you would incorrectly conclude that it is a parameter even though it is a member. You should work with the SemanticModel to determine what a SymbolKind is. You can use SemanticModel.GetDeclaredSymbol on declarations and SemanticModel.GetSymbolInfo().Symbol on symbol usages. Once you have the ISymbol it's easy to determine its kind. Bear in mind that different symbols have their own "sub-kinds", for instance ITypeSymbol has TypeKind property that determines if the type is Class, Struct, Interface, Array etc., so you should check them up.

You can use the following code to get the field information for class and parameters. Note, however, the detection of the method field is unavailable. This code uses reflection to query the assembly information and enumerates and compares the results.
static class Program
{
static void Main(string[] args)
{
SomeMethod("Hello, World!!!");
Type testType = typeof(Program);
FieldInfo[] fieldInfo = testType.GetFields();
MethodInfo methodInfo = testType.GetMethod("SomeMethod");
Console.WriteLine("Parameter type:{0}", TypeOfField(fieldInfo, methodInfo, "sampleString"));
Console.WriteLine("Parameter type:{0}", TypeOfField(fieldInfo, methodInfo, "classField"));
Console.WriteLine("Parameter type:{0}", TypeOfField(fieldInfo, methodInfo, "helloWorld"));
Console.WriteLine("Parameter type:{0}", TypeOfField(fieldInfo, methodInfo, "nonexistentVariable"));
}
public static string classField = "Hello, World!!!";
public static void SomeMethod(string sampleString)
{
string helloWorld = sampleString;
}
public static string TypeOfField(FieldInfo[] fieldInfo, MethodInfo methodInfo, string fieldName)
{
if (IsClassField(fieldInfo, fieldName))
{
return "Class Field";
}
else if (IsParameter(methodInfo, fieldName))
{
return "Parameter";
}
else
{
return "Cannot determine";
}
}
private static bool IsClassField(FieldInfo[] fieldInfo, string classFieldName)
{
bool isClassField = false;
foreach (var item in fieldInfo)
{
if (item.Name == classFieldName)
{
isClassField = true;
break;
}
}
return isClassField;
}
private static bool IsParameter(MethodInfo methodInfo, string parameterName)
{
bool isParameter = false;
ParameterInfo[] paramInfo = methodInfo.GetParameters();
foreach (var item in paramInfo)
{
if (item.Name == parameterName)
{
isParameter = true;
break;
}
}
return isParameter;
}
}

You can distinguish whether you are dealing with a class field vs a method's parameter or a local variable with the keyword this. If you had a class field string called sampleString and you wanted to refer to the class field rather then the local variable/ method parameter then you would refer to it with this.sampleString. You would refer to the local variable/ method parameter as sampleString without the keyword (this). In terms of local variables and method parameters, you are not able to have a local variable and method parameter with the same name within the same method. With your code above you are referring to the sampleString parameter.

Related

How to use bracket notation to access model property inside the loop in c# [duplicate]

I am trying implement the Data transformation using Reflection1 example in my code.
The GetSourceValue function has a switch comparing various types, but I want to remove these types and properties and have GetSourceValue get the value of the property using only a single string as the parameter. I want to pass a class and property in the string and resolve the value of the property.
Is this possible?
1 Web Archive version of original blog post

public static object GetPropValue(object src, string propName)
{
return src.GetType().GetProperty(propName).GetValue(src, null);
}
Of course, you will want to add validation and whatnot, but that is the gist of it.

How about something like this:
public static Object GetPropValue(this Object obj, String name) {
foreach (String part in name.Split('.')) {
if (obj == null) { return null; }
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
public static T GetPropValue<T>(this Object obj, String name) {
Object retval = GetPropValue(obj, name);
if (retval == null) { return default(T); }
// throws InvalidCastException if types are incompatible
return (T) retval;
}
This will allow you to descend into properties using a single string, like this:
DateTime now = DateTime.Now;
int min = GetPropValue<int>(now, "TimeOfDay.Minutes");
int hrs = now.GetPropValue<int>("TimeOfDay.Hours");
You can either use these methods as static methods or extensions.

Add to any Class:
public class Foo
{
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
public string Bar { get; set; }
}
Then, you can use as:
Foo f = new Foo();
// Set
f["Bar"] = "asdf";
// Get
string s = (string)f["Bar"];

What about using the CallByName of the Microsoft.VisualBasic namespace (Microsoft.VisualBasic.dll)? It uses reflection to get properties, fields, and methods of normal objects, COM objects, and even dynamic objects.
using Microsoft.VisualBasic;
using Microsoft.VisualBasic.CompilerServices;
and then
Versioned.CallByName(this, "method/function/prop name", CallType.Get).ToString();

Great answer by jheddings. I would like to improve it by allowing referencing of aggregated arrays or collections of objects, so that propertyName could be property1.property2[X].property3:
public static object GetPropertyValue(object srcobj, string propertyName)
{
if (srcobj == null)
return null;
object obj = srcobj;
// Split property name to parts (propertyName could be hierarchical, like obj.subobj.subobj.property
string[] propertyNameParts = propertyName.Split('.');
foreach (string propertyNamePart in propertyNameParts)
{
if (obj == null) return null;
// propertyNamePart could contain reference to specific
// element (by index) inside a collection
if (!propertyNamePart.Contains("["))
{
PropertyInfo pi = obj.GetType().GetProperty(propertyNamePart);
if (pi == null) return null;
obj = pi.GetValue(obj, null);
}
else
{ // propertyNamePart is areference to specific element
// (by index) inside a collection
// like AggregatedCollection[123]
// get collection name and element index
int indexStart = propertyNamePart.IndexOf("[")+1;
string collectionPropertyName = propertyNamePart.Substring(0, indexStart-1);
int collectionElementIndex = Int32.Parse(propertyNamePart.Substring(indexStart, propertyNamePart.Length-indexStart-1));
// get collection object
PropertyInfo pi = obj.GetType().GetProperty(collectionPropertyName);
if (pi == null) return null;
object unknownCollection = pi.GetValue(obj, null);
// try to process the collection as array
if (unknownCollection.GetType().IsArray)
{
object[] collectionAsArray = unknownCollection as object[];
obj = collectionAsArray[collectionElementIndex];
}
else
{
// try to process the collection as IList
System.Collections.IList collectionAsList = unknownCollection as System.Collections.IList;
if (collectionAsList != null)
{
obj = collectionAsList[collectionElementIndex];
}
else
{
// ??? Unsupported collection type
}
}
}
}
return obj;
}

If I use the code from Ed S. I get
'ReflectionExtensions.GetProperty(Type, string)' is inaccessible due to its protection level
It seems that GetProperty() is not available in Xamarin.Forms. TargetFrameworkProfile is Profile7 in my Portable Class Library (.NET Framework 4.5, Windows 8, ASP.NET Core 1.0, Xamarin.Android, Xamarin.iOS, Xamarin.iOS Classic).
Now I found a working solution:
using System.Linq;
using System.Reflection;
public static object GetPropValue(object source, string propertyName)
{
var property = source.GetType().GetRuntimeProperties().FirstOrDefault(p => string.Equals(p.Name, propertyName, StringComparison.OrdinalIgnoreCase));
return property?.GetValue(source);
}
Source

About the nested properties discussion, you can avoid all the reflection stuff if you use the DataBinder.Eval Method (Object, String) as below:
var value = DataBinder.Eval(DateTime.Now, "TimeOfDay.Hours");
Of course, you'll need to add a reference to the System.Web assembly, but this probably isn't a big deal.

The method to call has changed in .NET Standard (as of 1.6). Also we can use C# 6's null conditional operator.
using System.Reflection;
public static object GetPropValue(object src, string propName)
{
return src.GetType().GetRuntimeProperty(propName)?.GetValue(src);
}

The below method works perfect for me:
class MyClass {
public string prop1 { set; get; }
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
}
To get the property value:
MyClass t1 = new MyClass();
...
string value = t1["prop1"].ToString();
To set the property value:
t1["prop1"] = value;

public static List<KeyValuePair<string, string>> GetProperties(object item) //where T : class
{
var result = new List<KeyValuePair<string, string>>();
if (item != null)
{
var type = item.GetType();
var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var pi in properties)
{
var selfValue = type.GetProperty(pi.Name).GetValue(item, null);
if (selfValue != null)
{
result.Add(new KeyValuePair<string, string>(pi.Name, selfValue.ToString()));
}
else
{
result.Add(new KeyValuePair<string, string>(pi.Name, null));
}
}
}
return result;
}
This is a way to get all properties with their values in a List.

Using PropertyInfo of the System.Reflection namespace. Reflection compiles just fine no matter what property we try to access. The error will come up during run-time.
public static object GetObjProperty(object obj, string property)
{
Type t = obj.GetType();
PropertyInfo p = t.GetProperty("Location");
Point location = (Point)p.GetValue(obj, null);
return location;
}
It works fine to get the Location property of an object
Label1.Text = GetObjProperty(button1, "Location").ToString();
We'll get the Location : {X=71,Y=27}
We can also return location.X or location.Y on the same way.

public class YourClass
{
//Add below line in your class
public object this[string propertyName] => GetType().GetProperty(propertyName)?.GetValue(this, null);
public string SampleProperty { get; set; }
}
//And you can get value of any property like this.
var value = YourClass["SampleProperty"];

The following code is a Recursive method for displaying the entire hierarchy of all of the Property Names and Values contained in an object's instance. This method uses a simplified version of AlexD's GetPropertyValue() answer above in this thread. Thanks to this discussion thread, I was able to figure out how to do this!
For example, I use this method to show an explosion or dump of all of the properties in a WebService response by calling the method as follows:
PropertyValues_byRecursion("Response", response, false);
public static object GetPropertyValue(object srcObj, string propertyName)
{
if (srcObj == null)
{
return null;
}
PropertyInfo pi = srcObj.GetType().GetProperty(propertyName.Replace("[]", ""));
if (pi == null)
{
return null;
}
return pi.GetValue(srcObj);
}
public static void PropertyValues_byRecursion(string parentPath, object parentObj, bool showNullValues)
{
/// Processes all of the objects contained in the parent object.
/// If an object has a Property Value, then the value is written to the Console
/// Else if the object is a container, then this method is called recursively
/// using the current path and current object as parameters
// Note: If you do not want to see null values, set showNullValues = false
foreach (PropertyInfo pi in parentObj.GetType().GetTypeInfo().GetProperties())
{
// Build the current object property's namespace path.
// Recursion extends this to be the property's full namespace path.
string currentPath = parentPath + "." + pi.Name;
// Get the selected property's value as an object
object myPropertyValue = GetPropertyValue(parentObj, pi.Name);
if (myPropertyValue == null)
{
// Instance of Property does not exist
if (showNullValues)
{
Console.WriteLine(currentPath + " = null");
// Note: If you are replacing these Console.Write... methods callback methods,
// consider passing DBNull.Value instead of null in any method object parameters.
}
}
else if (myPropertyValue.GetType().IsArray)
{
// myPropertyValue is an object instance of an Array of business objects.
// Initialize an array index variable so we can show NamespacePath[idx] in the results.
int idx = 0;
foreach (object business in (Array)myPropertyValue)
{
if (business == null)
{
// Instance of Property does not exist
// Not sure if this is possible in this context.
if (showNullValues)
{
Console.WriteLine(currentPath + "[" + idx.ToString() + "]" + " = null");
}
}
else if (business.GetType().IsArray)
{
// myPropertyValue[idx] is another Array!
// Let recursion process it.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
else if (business.GetType().IsSealed)
{
// Display the Full Property Path and its Value
Console.WriteLine(currentPath + "[" + idx.ToString() + "] = " + business.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
idx++;
}
}
else if (myPropertyValue.GetType().IsSealed)
{
// myPropertyValue is a simple value
Console.WriteLine(currentPath + " = " + myPropertyValue.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath, myPropertyValue, showNullValues);
}
}
}

public static TValue GetFieldValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetFields(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.FieldType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}
public static TValue GetPropertyValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetProperties(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.PropertyType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}

Dim NewHandle As YourType = CType(Microsoft.VisualBasic.CallByName(ObjectThatContainsYourVariable, "YourVariableName", CallType), YourType)

Here is another way to find a nested property that doesn't require the string to tell you the nesting path. Credit to Ed S. for the single property method.
public static T FindNestedPropertyValue<T, N>(N model, string propName) {
T retVal = default(T);
bool found = false;
PropertyInfo[] properties = typeof(N).GetProperties();
foreach (PropertyInfo property in properties) {
var currentProperty = property.GetValue(model, null);
if (!found) {
try {
retVal = GetPropValue<T>(currentProperty, propName);
found = true;
} catch { }
}
}
if (!found) {
throw new Exception("Unable to find property: " + propName);
}
return retVal;
}
public static T GetPropValue<T>(object srcObject, string propName) {
return (T)srcObject.GetType().GetProperty(propName).GetValue(srcObject, null);
}

You never mention what object you are inspecting, and since you are rejecting ones that reference a given object, I will assume you mean a static one.
using System.Reflection;
public object GetPropValue(string prop)
{
int splitPoint = prop.LastIndexOf('.');
Type type = Assembly.GetEntryAssembly().GetType(prop.Substring(0, splitPoint));
object obj = null;
return type.GetProperty(prop.Substring(splitPoint + 1)).GetValue(obj, null);
}
Note that I marked the object that is being inspected with the local variable obj. null means static, otherwise set it to what you want. Also note that the GetEntryAssembly() is one of a few available methods to get the "running" assembly, you may want to play around with it if you are having a hard time loading the type.

Have a look at the Heleonix.Reflection library. You can get/set/invoke members by paths, or create a getter/setter (lambda compiled into a delegate) which is faster than reflection. For example:
var success = Reflector.Get(DateTime.Now, null, "Date.Year", out int value);
Or create a getter once and cache for reuse (this is more performant but might throw NullReferenceException if an intermediate member is null):
var getter = Reflector.CreateGetter<DateTime, int>("Date.Year", typeof(DateTime));
getter(DateTime.Now);
Or if you want to create a List<Action<object, object>> of different getters, just specify base types for compiled delegates (type conversions will be added into compiled lambdas):
var getter = Reflector.CreateGetter<object, object>("Date.Year", typeof(DateTime));
getter(DateTime.Now);

Although the original question was about how to get the value of the property using only a single string as the parameter, it makes a lot of sense here to use an Expression rather than simply a string to ensure that the caller never uses a hard coded property name. Here is a one line version with usage:
public static class Utils
...
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
=> (TVal)((x.Body as MemberExpression)?.Member as PropertyInfo)!.GetValue(t);
...
var val = Utils.GetPropertyValue(foo, p => p.Bar);
Here is a slightly better version in terms of readability a error handling:
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
{
var m = (x.Body as MemberExpression)?.Member;
var p = m as PropertyInfo;
if (null == p)
throw new ArgumentException($"Unknown property: {typeof(T).Name}.{(m?.Name??"???")}");
return (TVal)p.GetValue(t);
}
In short you pass in a lambda expression reading a property. The body of the lambda - the part on the right of the fat arrow - is a member expression from which you can get the member name and which you can cast to a PropertyInfo, provided the member is actually a Property and not, for instance, a method.
In the short version, the null forgiving operator - the ! in the expression - tells the compiler that the PropertyInfo will not be null. This is a big lie and you will get a NullReferenceException at runtime. The longer version gives you the name of the property if it manages to get it.
PS: Thanks to Oleg G. for the initial version of this code :)

shorter way ....
var a = new Test { Id = 1 , Name = "A" , date = DateTime.Now};
var b = new Test { Id = 1 , Name = "AXXX", date = DateTime.Now };
var compare = string.Join("",a.GetType().GetProperties().Select(x => x.GetValue(a)).ToArray())==
string.Join("",b.GetType().GetProperties().Select(x => x.GetValue(b)).ToArray());

jheddings and AlexD both wrote excellent answers on how to resolve property strings. I'd like to throw mine in the mix, since I wrote a dedicated library exactly for that purpose.
Pather.CSharp's main class is Resolver. Per default it can resolve properties, array and dictionary entries.
So, for example, if you have an object like this
var o = new { Property1 = new { Property2 = "value" } };
and want to get Property2, you can do it like this:
IResolver resolver = new Resolver();
var path = "Property1.Property2";
object result = r.Resolve(o, path);
//=> "value"
This is the most basic example of the paths it can resolve. If you want to see what else it can, or how you can extend it, just head to its Github page.

Here's what I got based on other answers. A little overkill on getting so specific with the error handling.
public static T GetPropertyValue<T>(object sourceInstance, string targetPropertyName, bool throwExceptionIfNotExists = false)
{
string errorMsg = null;
try
{
if (sourceInstance == null || string.IsNullOrWhiteSpace(targetPropertyName))
{
errorMsg = $"Source object is null or property name is null or whitespace. '{targetPropertyName}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
Type returnType = typeof(T);
Type sourceType = sourceInstance.GetType();
PropertyInfo propertyInfo = sourceType.GetProperty(targetPropertyName, returnType);
if (propertyInfo == null)
{
errorMsg = $"Property name '{targetPropertyName}' of type '{returnType}' not found for source object of type '{sourceType}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
return (T)propertyInfo.GetValue(sourceInstance, null);
}
catch(Exception ex)
{
errorMsg = $"Problem getting property name '{targetPropertyName}' from source instance.";
Log.Error(errorMsg, ex);
if (throwExceptionIfNotExists)
throw;
}
return default(T);
}

Here is my solution. It works also with COM objects and allows to access collection/array items from COM objects.
public static object GetPropValue(this object obj, string name)
{
foreach (string part in name.Split('.'))
{
if (obj == null) { return null; }
Type type = obj.GetType();
if (type.Name == "__ComObject")
{
if (part.Contains('['))
{
string partWithoundIndex = part;
int index = ParseIndexFromPropertyName(ref partWithoundIndex);
obj = Versioned.CallByName(obj, partWithoundIndex, CallType.Get, index);
}
else
{
obj = Versioned.CallByName(obj, part, CallType.Get);
}
}
else
{
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
}
return obj;
}
private static int ParseIndexFromPropertyName(ref string name)
{
int index = -1;
int s = name.IndexOf('[') + 1;
int e = name.IndexOf(']');
if (e < s)
{
throw new ArgumentException();
}
string tmp = name.Substring(s, e - s);
index = Convert.ToInt32(tmp);
name = name.Substring(0, s - 1);
return index;
}

Whenever you want to loop over all properties in on an object and then use each value of the property must use this piece of code:
foreach (var property in request.GetType().GetProperties())
{
var valueOfProperty = property.GetValue(properties, null);
}

How to access property of object with a variable name [duplicate]

I am trying implement the Data transformation using Reflection1 example in my code.
The GetSourceValue function has a switch comparing various types, but I want to remove these types and properties and have GetSourceValue get the value of the property using only a single string as the parameter. I want to pass a class and property in the string and resolve the value of the property.
Is this possible?
1 Web Archive version of original blog post

public static object GetPropValue(object src, string propName)
{
return src.GetType().GetProperty(propName).GetValue(src, null);
}
Of course, you will want to add validation and whatnot, but that is the gist of it.

How about something like this:
public static Object GetPropValue(this Object obj, String name) {
foreach (String part in name.Split('.')) {
if (obj == null) { return null; }
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
public static T GetPropValue<T>(this Object obj, String name) {
Object retval = GetPropValue(obj, name);
if (retval == null) { return default(T); }
// throws InvalidCastException if types are incompatible
return (T) retval;
}
This will allow you to descend into properties using a single string, like this:
DateTime now = DateTime.Now;
int min = GetPropValue<int>(now, "TimeOfDay.Minutes");
int hrs = now.GetPropValue<int>("TimeOfDay.Hours");
You can either use these methods as static methods or extensions.

Add to any Class:
public class Foo
{
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
public string Bar { get; set; }
}
Then, you can use as:
Foo f = new Foo();
// Set
f["Bar"] = "asdf";
// Get
string s = (string)f["Bar"];

What about using the CallByName of the Microsoft.VisualBasic namespace (Microsoft.VisualBasic.dll)? It uses reflection to get properties, fields, and methods of normal objects, COM objects, and even dynamic objects.
using Microsoft.VisualBasic;
using Microsoft.VisualBasic.CompilerServices;
and then
Versioned.CallByName(this, "method/function/prop name", CallType.Get).ToString();

Great answer by jheddings. I would like to improve it by allowing referencing of aggregated arrays or collections of objects, so that propertyName could be property1.property2[X].property3:
public static object GetPropertyValue(object srcobj, string propertyName)
{
if (srcobj == null)
return null;
object obj = srcobj;
// Split property name to parts (propertyName could be hierarchical, like obj.subobj.subobj.property
string[] propertyNameParts = propertyName.Split('.');
foreach (string propertyNamePart in propertyNameParts)
{
if (obj == null) return null;
// propertyNamePart could contain reference to specific
// element (by index) inside a collection
if (!propertyNamePart.Contains("["))
{
PropertyInfo pi = obj.GetType().GetProperty(propertyNamePart);
if (pi == null) return null;
obj = pi.GetValue(obj, null);
}
else
{ // propertyNamePart is areference to specific element
// (by index) inside a collection
// like AggregatedCollection[123]
// get collection name and element index
int indexStart = propertyNamePart.IndexOf("[")+1;
string collectionPropertyName = propertyNamePart.Substring(0, indexStart-1);
int collectionElementIndex = Int32.Parse(propertyNamePart.Substring(indexStart, propertyNamePart.Length-indexStart-1));
// get collection object
PropertyInfo pi = obj.GetType().GetProperty(collectionPropertyName);
if (pi == null) return null;
object unknownCollection = pi.GetValue(obj, null);
// try to process the collection as array
if (unknownCollection.GetType().IsArray)
{
object[] collectionAsArray = unknownCollection as object[];
obj = collectionAsArray[collectionElementIndex];
}
else
{
// try to process the collection as IList
System.Collections.IList collectionAsList = unknownCollection as System.Collections.IList;
if (collectionAsList != null)
{
obj = collectionAsList[collectionElementIndex];
}
else
{
// ??? Unsupported collection type
}
}
}
}
return obj;
}

If I use the code from Ed S. I get
'ReflectionExtensions.GetProperty(Type, string)' is inaccessible due to its protection level
It seems that GetProperty() is not available in Xamarin.Forms. TargetFrameworkProfile is Profile7 in my Portable Class Library (.NET Framework 4.5, Windows 8, ASP.NET Core 1.0, Xamarin.Android, Xamarin.iOS, Xamarin.iOS Classic).
Now I found a working solution:
using System.Linq;
using System.Reflection;
public static object GetPropValue(object source, string propertyName)
{
var property = source.GetType().GetRuntimeProperties().FirstOrDefault(p => string.Equals(p.Name, propertyName, StringComparison.OrdinalIgnoreCase));
return property?.GetValue(source);
}
Source

About the nested properties discussion, you can avoid all the reflection stuff if you use the DataBinder.Eval Method (Object, String) as below:
var value = DataBinder.Eval(DateTime.Now, "TimeOfDay.Hours");
Of course, you'll need to add a reference to the System.Web assembly, but this probably isn't a big deal.

The method to call has changed in .NET Standard (as of 1.6). Also we can use C# 6's null conditional operator.
using System.Reflection;
public static object GetPropValue(object src, string propName)
{
return src.GetType().GetRuntimeProperty(propName)?.GetValue(src);
}

The below method works perfect for me:
class MyClass {
public string prop1 { set; get; }
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
}
To get the property value:
MyClass t1 = new MyClass();
...
string value = t1["prop1"].ToString();
To set the property value:
t1["prop1"] = value;

public static List<KeyValuePair<string, string>> GetProperties(object item) //where T : class
{
var result = new List<KeyValuePair<string, string>>();
if (item != null)
{
var type = item.GetType();
var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var pi in properties)
{
var selfValue = type.GetProperty(pi.Name).GetValue(item, null);
if (selfValue != null)
{
result.Add(new KeyValuePair<string, string>(pi.Name, selfValue.ToString()));
}
else
{
result.Add(new KeyValuePair<string, string>(pi.Name, null));
}
}
}
return result;
}
This is a way to get all properties with their values in a List.

Using PropertyInfo of the System.Reflection namespace. Reflection compiles just fine no matter what property we try to access. The error will come up during run-time.
public static object GetObjProperty(object obj, string property)
{
Type t = obj.GetType();
PropertyInfo p = t.GetProperty("Location");
Point location = (Point)p.GetValue(obj, null);
return location;
}
It works fine to get the Location property of an object
Label1.Text = GetObjProperty(button1, "Location").ToString();
We'll get the Location : {X=71,Y=27}
We can also return location.X or location.Y on the same way.

public class YourClass
{
//Add below line in your class
public object this[string propertyName] => GetType().GetProperty(propertyName)?.GetValue(this, null);
public string SampleProperty { get; set; }
}
//And you can get value of any property like this.
var value = YourClass["SampleProperty"];

The following code is a Recursive method for displaying the entire hierarchy of all of the Property Names and Values contained in an object's instance. This method uses a simplified version of AlexD's GetPropertyValue() answer above in this thread. Thanks to this discussion thread, I was able to figure out how to do this!
For example, I use this method to show an explosion or dump of all of the properties in a WebService response by calling the method as follows:
PropertyValues_byRecursion("Response", response, false);
public static object GetPropertyValue(object srcObj, string propertyName)
{
if (srcObj == null)
{
return null;
}
PropertyInfo pi = srcObj.GetType().GetProperty(propertyName.Replace("[]", ""));
if (pi == null)
{
return null;
}
return pi.GetValue(srcObj);
}
public static void PropertyValues_byRecursion(string parentPath, object parentObj, bool showNullValues)
{
/// Processes all of the objects contained in the parent object.
/// If an object has a Property Value, then the value is written to the Console
/// Else if the object is a container, then this method is called recursively
/// using the current path and current object as parameters
// Note: If you do not want to see null values, set showNullValues = false
foreach (PropertyInfo pi in parentObj.GetType().GetTypeInfo().GetProperties())
{
// Build the current object property's namespace path.
// Recursion extends this to be the property's full namespace path.
string currentPath = parentPath + "." + pi.Name;
// Get the selected property's value as an object
object myPropertyValue = GetPropertyValue(parentObj, pi.Name);
if (myPropertyValue == null)
{
// Instance of Property does not exist
if (showNullValues)
{
Console.WriteLine(currentPath + " = null");
// Note: If you are replacing these Console.Write... methods callback methods,
// consider passing DBNull.Value instead of null in any method object parameters.
}
}
else if (myPropertyValue.GetType().IsArray)
{
// myPropertyValue is an object instance of an Array of business objects.
// Initialize an array index variable so we can show NamespacePath[idx] in the results.
int idx = 0;
foreach (object business in (Array)myPropertyValue)
{
if (business == null)
{
// Instance of Property does not exist
// Not sure if this is possible in this context.
if (showNullValues)
{
Console.WriteLine(currentPath + "[" + idx.ToString() + "]" + " = null");
}
}
else if (business.GetType().IsArray)
{
// myPropertyValue[idx] is another Array!
// Let recursion process it.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
else if (business.GetType().IsSealed)
{
// Display the Full Property Path and its Value
Console.WriteLine(currentPath + "[" + idx.ToString() + "] = " + business.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
idx++;
}
}
else if (myPropertyValue.GetType().IsSealed)
{
// myPropertyValue is a simple value
Console.WriteLine(currentPath + " = " + myPropertyValue.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath, myPropertyValue, showNullValues);
}
}
}

public static TValue GetFieldValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetFields(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.FieldType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}
public static TValue GetPropertyValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetProperties(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.PropertyType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}

Dim NewHandle As YourType = CType(Microsoft.VisualBasic.CallByName(ObjectThatContainsYourVariable, "YourVariableName", CallType), YourType)

Here is another way to find a nested property that doesn't require the string to tell you the nesting path. Credit to Ed S. for the single property method.
public static T FindNestedPropertyValue<T, N>(N model, string propName) {
T retVal = default(T);
bool found = false;
PropertyInfo[] properties = typeof(N).GetProperties();
foreach (PropertyInfo property in properties) {
var currentProperty = property.GetValue(model, null);
if (!found) {
try {
retVal = GetPropValue<T>(currentProperty, propName);
found = true;
} catch { }
}
}
if (!found) {
throw new Exception("Unable to find property: " + propName);
}
return retVal;
}
public static T GetPropValue<T>(object srcObject, string propName) {
return (T)srcObject.GetType().GetProperty(propName).GetValue(srcObject, null);
}

You never mention what object you are inspecting, and since you are rejecting ones that reference a given object, I will assume you mean a static one.
using System.Reflection;
public object GetPropValue(string prop)
{
int splitPoint = prop.LastIndexOf('.');
Type type = Assembly.GetEntryAssembly().GetType(prop.Substring(0, splitPoint));
object obj = null;
return type.GetProperty(prop.Substring(splitPoint + 1)).GetValue(obj, null);
}
Note that I marked the object that is being inspected with the local variable obj. null means static, otherwise set it to what you want. Also note that the GetEntryAssembly() is one of a few available methods to get the "running" assembly, you may want to play around with it if you are having a hard time loading the type.

Have a look at the Heleonix.Reflection library. You can get/set/invoke members by paths, or create a getter/setter (lambda compiled into a delegate) which is faster than reflection. For example:
var success = Reflector.Get(DateTime.Now, null, "Date.Year", out int value);
Or create a getter once and cache for reuse (this is more performant but might throw NullReferenceException if an intermediate member is null):
var getter = Reflector.CreateGetter<DateTime, int>("Date.Year", typeof(DateTime));
getter(DateTime.Now);
Or if you want to create a List<Action<object, object>> of different getters, just specify base types for compiled delegates (type conversions will be added into compiled lambdas):
var getter = Reflector.CreateGetter<object, object>("Date.Year", typeof(DateTime));
getter(DateTime.Now);

Although the original question was about how to get the value of the property using only a single string as the parameter, it makes a lot of sense here to use an Expression rather than simply a string to ensure that the caller never uses a hard coded property name. Here is a one line version with usage:
public static class Utils
...
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
=> (TVal)((x.Body as MemberExpression)?.Member as PropertyInfo)!.GetValue(t);
...
var val = Utils.GetPropertyValue(foo, p => p.Bar);
Here is a slightly better version in terms of readability a error handling:
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
{
var m = (x.Body as MemberExpression)?.Member;
var p = m as PropertyInfo;
if (null == p)
throw new ArgumentException($"Unknown property: {typeof(T).Name}.{(m?.Name??"???")}");
return (TVal)p.GetValue(t);
}
In short you pass in a lambda expression reading a property. The body of the lambda - the part on the right of the fat arrow - is a member expression from which you can get the member name and which you can cast to a PropertyInfo, provided the member is actually a Property and not, for instance, a method.
In the short version, the null forgiving operator - the ! in the expression - tells the compiler that the PropertyInfo will not be null. This is a big lie and you will get a NullReferenceException at runtime. The longer version gives you the name of the property if it manages to get it.
PS: Thanks to Oleg G. for the initial version of this code :)

shorter way ....
var a = new Test { Id = 1 , Name = "A" , date = DateTime.Now};
var b = new Test { Id = 1 , Name = "AXXX", date = DateTime.Now };
var compare = string.Join("",a.GetType().GetProperties().Select(x => x.GetValue(a)).ToArray())==
string.Join("",b.GetType().GetProperties().Select(x => x.GetValue(b)).ToArray());

jheddings and AlexD both wrote excellent answers on how to resolve property strings. I'd like to throw mine in the mix, since I wrote a dedicated library exactly for that purpose.
Pather.CSharp's main class is Resolver. Per default it can resolve properties, array and dictionary entries.
So, for example, if you have an object like this
var o = new { Property1 = new { Property2 = "value" } };
and want to get Property2, you can do it like this:
IResolver resolver = new Resolver();
var path = "Property1.Property2";
object result = r.Resolve(o, path);
//=> "value"
This is the most basic example of the paths it can resolve. If you want to see what else it can, or how you can extend it, just head to its Github page.

Here's what I got based on other answers. A little overkill on getting so specific with the error handling.
public static T GetPropertyValue<T>(object sourceInstance, string targetPropertyName, bool throwExceptionIfNotExists = false)
{
string errorMsg = null;
try
{
if (sourceInstance == null || string.IsNullOrWhiteSpace(targetPropertyName))
{
errorMsg = $"Source object is null or property name is null or whitespace. '{targetPropertyName}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
Type returnType = typeof(T);
Type sourceType = sourceInstance.GetType();
PropertyInfo propertyInfo = sourceType.GetProperty(targetPropertyName, returnType);
if (propertyInfo == null)
{
errorMsg = $"Property name '{targetPropertyName}' of type '{returnType}' not found for source object of type '{sourceType}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
return (T)propertyInfo.GetValue(sourceInstance, null);
}
catch(Exception ex)
{
errorMsg = $"Problem getting property name '{targetPropertyName}' from source instance.";
Log.Error(errorMsg, ex);
if (throwExceptionIfNotExists)
throw;
}
return default(T);
}

Here is my solution. It works also with COM objects and allows to access collection/array items from COM objects.
public static object GetPropValue(this object obj, string name)
{
foreach (string part in name.Split('.'))
{
if (obj == null) { return null; }
Type type = obj.GetType();
if (type.Name == "__ComObject")
{
if (part.Contains('['))
{
string partWithoundIndex = part;
int index = ParseIndexFromPropertyName(ref partWithoundIndex);
obj = Versioned.CallByName(obj, partWithoundIndex, CallType.Get, index);
}
else
{
obj = Versioned.CallByName(obj, part, CallType.Get);
}
}
else
{
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
}
return obj;
}
private static int ParseIndexFromPropertyName(ref string name)
{
int index = -1;
int s = name.IndexOf('[') + 1;
int e = name.IndexOf(']');
if (e < s)
{
throw new ArgumentException();
}
string tmp = name.Substring(s, e - s);
index = Convert.ToInt32(tmp);
name = name.Substring(0, s - 1);
return index;
}

Whenever you want to loop over all properties in on an object and then use each value of the property must use this piece of code:
foreach (var property in request.GetType().GetProperties())
{
var valueOfProperty = property.GetValue(properties, null);
}

Enum get value by reference c# [duplicate]

I am trying implement the Data transformation using Reflection1 example in my code.
The GetSourceValue function has a switch comparing various types, but I want to remove these types and properties and have GetSourceValue get the value of the property using only a single string as the parameter. I want to pass a class and property in the string and resolve the value of the property.
Is this possible?
1 Web Archive version of original blog post

public static object GetPropValue(object src, string propName)
{
return src.GetType().GetProperty(propName).GetValue(src, null);
}
Of course, you will want to add validation and whatnot, but that is the gist of it.

How about something like this:
public static Object GetPropValue(this Object obj, String name) {
foreach (String part in name.Split('.')) {
if (obj == null) { return null; }
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
public static T GetPropValue<T>(this Object obj, String name) {
Object retval = GetPropValue(obj, name);
if (retval == null) { return default(T); }
// throws InvalidCastException if types are incompatible
return (T) retval;
}
This will allow you to descend into properties using a single string, like this:
DateTime now = DateTime.Now;
int min = GetPropValue<int>(now, "TimeOfDay.Minutes");
int hrs = now.GetPropValue<int>("TimeOfDay.Hours");
You can either use these methods as static methods or extensions.

Add to any Class:
public class Foo
{
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
public string Bar { get; set; }
}
Then, you can use as:
Foo f = new Foo();
// Set
f["Bar"] = "asdf";
// Get
string s = (string)f["Bar"];

What about using the CallByName of the Microsoft.VisualBasic namespace (Microsoft.VisualBasic.dll)? It uses reflection to get properties, fields, and methods of normal objects, COM objects, and even dynamic objects.
using Microsoft.VisualBasic;
using Microsoft.VisualBasic.CompilerServices;
and then
Versioned.CallByName(this, "method/function/prop name", CallType.Get).ToString();

Great answer by jheddings. I would like to improve it by allowing referencing of aggregated arrays or collections of objects, so that propertyName could be property1.property2[X].property3:
public static object GetPropertyValue(object srcobj, string propertyName)
{
if (srcobj == null)
return null;
object obj = srcobj;
// Split property name to parts (propertyName could be hierarchical, like obj.subobj.subobj.property
string[] propertyNameParts = propertyName.Split('.');
foreach (string propertyNamePart in propertyNameParts)
{
if (obj == null) return null;
// propertyNamePart could contain reference to specific
// element (by index) inside a collection
if (!propertyNamePart.Contains("["))
{
PropertyInfo pi = obj.GetType().GetProperty(propertyNamePart);
if (pi == null) return null;
obj = pi.GetValue(obj, null);
}
else
{ // propertyNamePart is areference to specific element
// (by index) inside a collection
// like AggregatedCollection[123]
// get collection name and element index
int indexStart = propertyNamePart.IndexOf("[")+1;
string collectionPropertyName = propertyNamePart.Substring(0, indexStart-1);
int collectionElementIndex = Int32.Parse(propertyNamePart.Substring(indexStart, propertyNamePart.Length-indexStart-1));
// get collection object
PropertyInfo pi = obj.GetType().GetProperty(collectionPropertyName);
if (pi == null) return null;
object unknownCollection = pi.GetValue(obj, null);
// try to process the collection as array
if (unknownCollection.GetType().IsArray)
{
object[] collectionAsArray = unknownCollection as object[];
obj = collectionAsArray[collectionElementIndex];
}
else
{
// try to process the collection as IList
System.Collections.IList collectionAsList = unknownCollection as System.Collections.IList;
if (collectionAsList != null)
{
obj = collectionAsList[collectionElementIndex];
}
else
{
// ??? Unsupported collection type
}
}
}
}
return obj;
}

If I use the code from Ed S. I get
'ReflectionExtensions.GetProperty(Type, string)' is inaccessible due to its protection level
It seems that GetProperty() is not available in Xamarin.Forms. TargetFrameworkProfile is Profile7 in my Portable Class Library (.NET Framework 4.5, Windows 8, ASP.NET Core 1.0, Xamarin.Android, Xamarin.iOS, Xamarin.iOS Classic).
Now I found a working solution:
using System.Linq;
using System.Reflection;
public static object GetPropValue(object source, string propertyName)
{
var property = source.GetType().GetRuntimeProperties().FirstOrDefault(p => string.Equals(p.Name, propertyName, StringComparison.OrdinalIgnoreCase));
return property?.GetValue(source);
}
Source

About the nested properties discussion, you can avoid all the reflection stuff if you use the DataBinder.Eval Method (Object, String) as below:
var value = DataBinder.Eval(DateTime.Now, "TimeOfDay.Hours");
Of course, you'll need to add a reference to the System.Web assembly, but this probably isn't a big deal.

The method to call has changed in .NET Standard (as of 1.6). Also we can use C# 6's null conditional operator.
using System.Reflection;
public static object GetPropValue(object src, string propName)
{
return src.GetType().GetRuntimeProperty(propName)?.GetValue(src);
}

The below method works perfect for me:
class MyClass {
public string prop1 { set; get; }
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
}
To get the property value:
MyClass t1 = new MyClass();
...
string value = t1["prop1"].ToString();
To set the property value:
t1["prop1"] = value;

public static List<KeyValuePair<string, string>> GetProperties(object item) //where T : class
{
var result = new List<KeyValuePair<string, string>>();
if (item != null)
{
var type = item.GetType();
var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var pi in properties)
{
var selfValue = type.GetProperty(pi.Name).GetValue(item, null);
if (selfValue != null)
{
result.Add(new KeyValuePair<string, string>(pi.Name, selfValue.ToString()));
}
else
{
result.Add(new KeyValuePair<string, string>(pi.Name, null));
}
}
}
return result;
}
This is a way to get all properties with their values in a List.

Using PropertyInfo of the System.Reflection namespace. Reflection compiles just fine no matter what property we try to access. The error will come up during run-time.
public static object GetObjProperty(object obj, string property)
{
Type t = obj.GetType();
PropertyInfo p = t.GetProperty("Location");
Point location = (Point)p.GetValue(obj, null);
return location;
}
It works fine to get the Location property of an object
Label1.Text = GetObjProperty(button1, "Location").ToString();
We'll get the Location : {X=71,Y=27}
We can also return location.X or location.Y on the same way.

public class YourClass
{
//Add below line in your class
public object this[string propertyName] => GetType().GetProperty(propertyName)?.GetValue(this, null);
public string SampleProperty { get; set; }
}
//And you can get value of any property like this.
var value = YourClass["SampleProperty"];

The following code is a Recursive method for displaying the entire hierarchy of all of the Property Names and Values contained in an object's instance. This method uses a simplified version of AlexD's GetPropertyValue() answer above in this thread. Thanks to this discussion thread, I was able to figure out how to do this!
For example, I use this method to show an explosion or dump of all of the properties in a WebService response by calling the method as follows:
PropertyValues_byRecursion("Response", response, false);
public static object GetPropertyValue(object srcObj, string propertyName)
{
if (srcObj == null)
{
return null;
}
PropertyInfo pi = srcObj.GetType().GetProperty(propertyName.Replace("[]", ""));
if (pi == null)
{
return null;
}
return pi.GetValue(srcObj);
}
public static void PropertyValues_byRecursion(string parentPath, object parentObj, bool showNullValues)
{
/// Processes all of the objects contained in the parent object.
/// If an object has a Property Value, then the value is written to the Console
/// Else if the object is a container, then this method is called recursively
/// using the current path and current object as parameters
// Note: If you do not want to see null values, set showNullValues = false
foreach (PropertyInfo pi in parentObj.GetType().GetTypeInfo().GetProperties())
{
// Build the current object property's namespace path.
// Recursion extends this to be the property's full namespace path.
string currentPath = parentPath + "." + pi.Name;
// Get the selected property's value as an object
object myPropertyValue = GetPropertyValue(parentObj, pi.Name);
if (myPropertyValue == null)
{
// Instance of Property does not exist
if (showNullValues)
{
Console.WriteLine(currentPath + " = null");
// Note: If you are replacing these Console.Write... methods callback methods,
// consider passing DBNull.Value instead of null in any method object parameters.
}
}
else if (myPropertyValue.GetType().IsArray)
{
// myPropertyValue is an object instance of an Array of business objects.
// Initialize an array index variable so we can show NamespacePath[idx] in the results.
int idx = 0;
foreach (object business in (Array)myPropertyValue)
{
if (business == null)
{
// Instance of Property does not exist
// Not sure if this is possible in this context.
if (showNullValues)
{
Console.WriteLine(currentPath + "[" + idx.ToString() + "]" + " = null");
}
}
else if (business.GetType().IsArray)
{
// myPropertyValue[idx] is another Array!
// Let recursion process it.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
else if (business.GetType().IsSealed)
{
// Display the Full Property Path and its Value
Console.WriteLine(currentPath + "[" + idx.ToString() + "] = " + business.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
idx++;
}
}
else if (myPropertyValue.GetType().IsSealed)
{
// myPropertyValue is a simple value
Console.WriteLine(currentPath + " = " + myPropertyValue.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath, myPropertyValue, showNullValues);
}
}
}

public static TValue GetFieldValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetFields(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.FieldType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}
public static TValue GetPropertyValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetProperties(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.PropertyType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}

Dim NewHandle As YourType = CType(Microsoft.VisualBasic.CallByName(ObjectThatContainsYourVariable, "YourVariableName", CallType), YourType)

Here is another way to find a nested property that doesn't require the string to tell you the nesting path. Credit to Ed S. for the single property method.
public static T FindNestedPropertyValue<T, N>(N model, string propName) {
T retVal = default(T);
bool found = false;
PropertyInfo[] properties = typeof(N).GetProperties();
foreach (PropertyInfo property in properties) {
var currentProperty = property.GetValue(model, null);
if (!found) {
try {
retVal = GetPropValue<T>(currentProperty, propName);
found = true;
} catch { }
}
}
if (!found) {
throw new Exception("Unable to find property: " + propName);
}
return retVal;
}
public static T GetPropValue<T>(object srcObject, string propName) {
return (T)srcObject.GetType().GetProperty(propName).GetValue(srcObject, null);
}

You never mention what object you are inspecting, and since you are rejecting ones that reference a given object, I will assume you mean a static one.
using System.Reflection;
public object GetPropValue(string prop)
{
int splitPoint = prop.LastIndexOf('.');
Type type = Assembly.GetEntryAssembly().GetType(prop.Substring(0, splitPoint));
object obj = null;
return type.GetProperty(prop.Substring(splitPoint + 1)).GetValue(obj, null);
}
Note that I marked the object that is being inspected with the local variable obj. null means static, otherwise set it to what you want. Also note that the GetEntryAssembly() is one of a few available methods to get the "running" assembly, you may want to play around with it if you are having a hard time loading the type.

Have a look at the Heleonix.Reflection library. You can get/set/invoke members by paths, or create a getter/setter (lambda compiled into a delegate) which is faster than reflection. For example:
var success = Reflector.Get(DateTime.Now, null, "Date.Year", out int value);
Or create a getter once and cache for reuse (this is more performant but might throw NullReferenceException if an intermediate member is null):
var getter = Reflector.CreateGetter<DateTime, int>("Date.Year", typeof(DateTime));
getter(DateTime.Now);
Or if you want to create a List<Action<object, object>> of different getters, just specify base types for compiled delegates (type conversions will be added into compiled lambdas):
var getter = Reflector.CreateGetter<object, object>("Date.Year", typeof(DateTime));
getter(DateTime.Now);

Although the original question was about how to get the value of the property using only a single string as the parameter, it makes a lot of sense here to use an Expression rather than simply a string to ensure that the caller never uses a hard coded property name. Here is a one line version with usage:
public static class Utils
...
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
=> (TVal)((x.Body as MemberExpression)?.Member as PropertyInfo)!.GetValue(t);
...
var val = Utils.GetPropertyValue(foo, p => p.Bar);
Here is a slightly better version in terms of readability a error handling:
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
{
var m = (x.Body as MemberExpression)?.Member;
var p = m as PropertyInfo;
if (null == p)
throw new ArgumentException($"Unknown property: {typeof(T).Name}.{(m?.Name??"???")}");
return (TVal)p.GetValue(t);
}
In short you pass in a lambda expression reading a property. The body of the lambda - the part on the right of the fat arrow - is a member expression from which you can get the member name and which you can cast to a PropertyInfo, provided the member is actually a Property and not, for instance, a method.
In the short version, the null forgiving operator - the ! in the expression - tells the compiler that the PropertyInfo will not be null. This is a big lie and you will get a NullReferenceException at runtime. The longer version gives you the name of the property if it manages to get it.
PS: Thanks to Oleg G. for the initial version of this code :)

shorter way ....
var a = new Test { Id = 1 , Name = "A" , date = DateTime.Now};
var b = new Test { Id = 1 , Name = "AXXX", date = DateTime.Now };
var compare = string.Join("",a.GetType().GetProperties().Select(x => x.GetValue(a)).ToArray())==
string.Join("",b.GetType().GetProperties().Select(x => x.GetValue(b)).ToArray());

jheddings and AlexD both wrote excellent answers on how to resolve property strings. I'd like to throw mine in the mix, since I wrote a dedicated library exactly for that purpose.
Pather.CSharp's main class is Resolver. Per default it can resolve properties, array and dictionary entries.
So, for example, if you have an object like this
var o = new { Property1 = new { Property2 = "value" } };
and want to get Property2, you can do it like this:
IResolver resolver = new Resolver();
var path = "Property1.Property2";
object result = r.Resolve(o, path);
//=> "value"
This is the most basic example of the paths it can resolve. If you want to see what else it can, or how you can extend it, just head to its Github page.

Here's what I got based on other answers. A little overkill on getting so specific with the error handling.
public static T GetPropertyValue<T>(object sourceInstance, string targetPropertyName, bool throwExceptionIfNotExists = false)
{
string errorMsg = null;
try
{
if (sourceInstance == null || string.IsNullOrWhiteSpace(targetPropertyName))
{
errorMsg = $"Source object is null or property name is null or whitespace. '{targetPropertyName}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
Type returnType = typeof(T);
Type sourceType = sourceInstance.GetType();
PropertyInfo propertyInfo = sourceType.GetProperty(targetPropertyName, returnType);
if (propertyInfo == null)
{
errorMsg = $"Property name '{targetPropertyName}' of type '{returnType}' not found for source object of type '{sourceType}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
return (T)propertyInfo.GetValue(sourceInstance, null);
}
catch(Exception ex)
{
errorMsg = $"Problem getting property name '{targetPropertyName}' from source instance.";
Log.Error(errorMsg, ex);
if (throwExceptionIfNotExists)
throw;
}
return default(T);
}

Here is my solution. It works also with COM objects and allows to access collection/array items from COM objects.
public static object GetPropValue(this object obj, string name)
{
foreach (string part in name.Split('.'))
{
if (obj == null) { return null; }
Type type = obj.GetType();
if (type.Name == "__ComObject")
{
if (part.Contains('['))
{
string partWithoundIndex = part;
int index = ParseIndexFromPropertyName(ref partWithoundIndex);
obj = Versioned.CallByName(obj, partWithoundIndex, CallType.Get, index);
}
else
{
obj = Versioned.CallByName(obj, part, CallType.Get);
}
}
else
{
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
}
return obj;
}
private static int ParseIndexFromPropertyName(ref string name)
{
int index = -1;
int s = name.IndexOf('[') + 1;
int e = name.IndexOf(']');
if (e < s)
{
throw new ArgumentException();
}
string tmp = name.Substring(s, e - s);
index = Convert.ToInt32(tmp);
name = name.Substring(0, s - 1);
return index;
}

Whenever you want to loop over all properties in on an object and then use each value of the property must use this piece of code:
foreach (var property in request.GetType().GetProperties())
{
var valueOfProperty = property.GetValue(properties, null);
}

Find which using directives are used in method

How can I know which using directives are used in the descendants of a given SyntaxNode.
See the following example:
https://dotnetfiddle.net/mCzNST
Here I want to know which usings are used in Class1, but ignore the usings that are used in Class2.

You can obtain the types relevant to the Syntax Nodes using the semantic model. The type info knows the related namespace which you can use to identify the relevant usings. When iterating through all nodes you receive the return values of methods as well as the types of variables, properties and fields. If you restrict the nodes to a specific type (e.g. InvocationExpressionSyntax) you only get return types, variable types, etc.
private static IEnumerable<string> FindUsedUsings(SemanticModel model, SyntaxNode node)
{
var resultList = new List<string>();
foreach (var identifier in node.DescendantNodesAndSelf())
{
var typeInfo = model.GetTypeInfo(identifier);
if (typeInfo.Type != null)
{
resultList.Add(typeInfo.Type.ContainingNamespace.ToDisplayString());
}
}
return resultList.Distinct().ToList();
}
However if you wish to obtain the usings you have to identify all declared types. I wrote an (incomplete) solution to identify three types of required usings:
using System;
using Text = System.String;
using static System.Console;
You can identify every type of using with a different logic.
For the first type of using you should consider:
var requires no using
PredefinedTypes (string, int) require no using
dynamic requires no using
QualifiedTypeNames require no using
For the second type of using you should consider:
While a type can be resolved using the alias you can also use the original name. Using the example from above, you could write the Statement string sample = Text.Empty;
For the third type of using you do not have an Identifier for the type, therefore you need to find the call using the Expression Statement.
Note that in the solution below a using static MyNamespace.Classname will not be resolved correctly as I was provided no TypeSymbol for the method's IdentifierNameSyntax so I couldn't resolve the type.
This can resolve in two problems:
If the type is not resolved a using static MyNamespace.Classname might be missing when analyzing the class MyNamespace.Class2
If the type is resolved an invalid using static MyNamespace.Classname might be present when analyzing the class MyNamespace.Classname (as the type name is not required within the class itself.
With that in mind here is the solution I came up with. There may be further special cases to consider, however I think it is a nice starting point:
private static IEnumerable<string> FindUsedUsings(SemanticModel model,
SyntaxNode node, SyntaxNode root)
{
var aliasResolution = new Dictionary<string, string>();
var usings = root.DescendantNodes().OfType<UsingDirectiveSyntax>();
foreach (var curr in usings)
{
var nameEquals = curr.DescendantNodes().
OfType<NameEqualsSyntax>().FirstOrDefault();
if (nameEquals != null)
{
var qualifiedName =
curr.DescendantNodes().OfType<QualifiedNameSyntax>().
FirstOrDefault()?.ToFullString();
if (qualifiedName != null)
{
aliasResolution.Add(nameEquals.Name.Identifier.Text, qualifiedName);
}
}
}
var currentNamespace = node.Ancestors().
OfType<NamespaceDeclarationSyntax>().FirstOrDefault();
var namespacename = currentNamespace?.Name.ToString();
if (namespacename == null)
{
// Empty namespace
namespacename = string.Empty;
}
var resultList = new List<string>();
foreach (var identifier in node.DescendantNodesAndSelf().OfType<TypeSyntax>())
{
if (identifier is PredefinedTypeSyntax || identifier.IsVar)
{
// No usings required for predefined types or var...
// [string, int, char, var, etc. do not need usings]
continue;
}
// If an alias is defined use it prioritized
if (GetUsingFromAlias(model, identifier, aliasResolution, resultList))
{
continue;
}
// If a type is provided, try to resolve it
if (GetUsingFromType(model, identifier, namespacename, resultList))
{
continue;
}
// If no type is provided check if the expression
// corresponds to a static member call
GetUsingFromStatic(model, identifier, resultList);
}
return resultList.Distinct().ToList();
}
private static void GetUsingFromStatic(SemanticModel model, TypeSyntax identifier,
List<string> resultList)
{
var symbol = model.GetSymbolInfo(identifier).Symbol;
// If the symbol (field, property, method call) can be resolved,
// is static and has a containing type
if (symbol != null && symbol.IsStatic && symbol.ContainingType != null)
{
var memberAccess = identifier.Parent as ExpressionSyntax;
if (memberAccess != null)
{
bool hasCallingType = false;
var children = memberAccess.ChildNodes();
foreach (var childNode in children)
{
// If the Expression has a Type
// (that is, if the expression is called from an identifyable source)
// no using static is required
var typeInfo = model.GetSymbolInfo(childNode).Symbol as INamedTypeSymbol;
if (typeInfo != null)
{
hasCallingType = true;
break;
}
}
// if the type-Info is missing a static using is required
if (!hasCallingType)
{
// type three using: using static [QualifiedType]
resultList.Add($"static {symbol.ContainingType}");
}
}
}
}
private static bool GetUsingFromType(SemanticModel model, TypeSyntax identifier,
string namespacename, List<string> resultList)
{
var typeInfo = model.GetSymbolInfo(identifier).Symbol as INamedTypeSymbol;
// dynamic is not required and not provided as an INamedTypeSymbol
if (typeInfo != null)
{
if (identifier is QualifiedNameSyntax
|| identifier.Parent is QualifiedNameSyntax)
{
// Qualified namespaces can be ignored...
return true;
}
var containingNamespace = typeInfo.ContainingNamespace.ToDisplayString();
// The current namespace need not be referenced
if (namespacename == containingNamespace)
{
return true;
}
// Type one using: using [Namespace];
resultList.Add(typeInfo.ContainingNamespace.ToDisplayString());
return true;
}
return false;
}
private static bool GetUsingFromAlias(SemanticModel model, TypeSyntax identifier,
Dictionary<string, string> aliasResolution, List<string> resultList)
{
var aliasInfo = model.GetAliasInfo(identifier);
// If the identifier is an alias
if (aliasInfo != null)
{
// check if it can be resolved
if (aliasResolution.ContainsKey(aliasInfo.Name))
{
// Type two using: using [Alias] = [QualifiedType];
resultList.Add($"{aliasInfo.Name} = {aliasResolution[aliasInfo.Name]}");
return true;
}
}
return false;
}

Get property value from string using reflection

I am trying implement the Data transformation using Reflection1 example in my code.
The GetSourceValue function has a switch comparing various types, but I want to remove these types and properties and have GetSourceValue get the value of the property using only a single string as the parameter. I want to pass a class and property in the string and resolve the value of the property.
Is this possible?
1 Web Archive version of original blog post

public static object GetPropValue(object src, string propName)
{
return src.GetType().GetProperty(propName).GetValue(src, null);
}
Of course, you will want to add validation and whatnot, but that is the gist of it.

How about something like this:
public static Object GetPropValue(this Object obj, String name) {
foreach (String part in name.Split('.')) {
if (obj == null) { return null; }
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
public static T GetPropValue<T>(this Object obj, String name) {
Object retval = GetPropValue(obj, name);
if (retval == null) { return default(T); }
// throws InvalidCastException if types are incompatible
return (T) retval;
}
This will allow you to descend into properties using a single string, like this:
DateTime now = DateTime.Now;
int min = GetPropValue<int>(now, "TimeOfDay.Minutes");
int hrs = now.GetPropValue<int>("TimeOfDay.Hours");
You can either use these methods as static methods or extensions.

Add to any Class:
public class Foo
{
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
public string Bar { get; set; }
}
Then, you can use as:
Foo f = new Foo();
// Set
f["Bar"] = "asdf";
// Get
string s = (string)f["Bar"];

What about using the CallByName of the Microsoft.VisualBasic namespace (Microsoft.VisualBasic.dll)? It uses reflection to get properties, fields, and methods of normal objects, COM objects, and even dynamic objects.
using Microsoft.VisualBasic;
using Microsoft.VisualBasic.CompilerServices;
and then
Versioned.CallByName(this, "method/function/prop name", CallType.Get).ToString();

Great answer by jheddings. I would like to improve it by allowing referencing of aggregated arrays or collections of objects, so that propertyName could be property1.property2[X].property3:
public static object GetPropertyValue(object srcobj, string propertyName)
{
if (srcobj == null)
return null;
object obj = srcobj;
// Split property name to parts (propertyName could be hierarchical, like obj.subobj.subobj.property
string[] propertyNameParts = propertyName.Split('.');
foreach (string propertyNamePart in propertyNameParts)
{
if (obj == null) return null;
// propertyNamePart could contain reference to specific
// element (by index) inside a collection
if (!propertyNamePart.Contains("["))
{
PropertyInfo pi = obj.GetType().GetProperty(propertyNamePart);
if (pi == null) return null;
obj = pi.GetValue(obj, null);
}
else
{ // propertyNamePart is areference to specific element
// (by index) inside a collection
// like AggregatedCollection[123]
// get collection name and element index
int indexStart = propertyNamePart.IndexOf("[")+1;
string collectionPropertyName = propertyNamePart.Substring(0, indexStart-1);
int collectionElementIndex = Int32.Parse(propertyNamePart.Substring(indexStart, propertyNamePart.Length-indexStart-1));
// get collection object
PropertyInfo pi = obj.GetType().GetProperty(collectionPropertyName);
if (pi == null) return null;
object unknownCollection = pi.GetValue(obj, null);
// try to process the collection as array
if (unknownCollection.GetType().IsArray)
{
object[] collectionAsArray = unknownCollection as object[];
obj = collectionAsArray[collectionElementIndex];
}
else
{
// try to process the collection as IList
System.Collections.IList collectionAsList = unknownCollection as System.Collections.IList;
if (collectionAsList != null)
{
obj = collectionAsList[collectionElementIndex];
}
else
{
// ??? Unsupported collection type
}
}
}
}
return obj;
}

If I use the code from Ed S. I get
'ReflectionExtensions.GetProperty(Type, string)' is inaccessible due to its protection level
It seems that GetProperty() is not available in Xamarin.Forms. TargetFrameworkProfile is Profile7 in my Portable Class Library (.NET Framework 4.5, Windows 8, ASP.NET Core 1.0, Xamarin.Android, Xamarin.iOS, Xamarin.iOS Classic).
Now I found a working solution:
using System.Linq;
using System.Reflection;
public static object GetPropValue(object source, string propertyName)
{
var property = source.GetType().GetRuntimeProperties().FirstOrDefault(p => string.Equals(p.Name, propertyName, StringComparison.OrdinalIgnoreCase));
return property?.GetValue(source);
}
Source

About the nested properties discussion, you can avoid all the reflection stuff if you use the DataBinder.Eval Method (Object, String) as below:
var value = DataBinder.Eval(DateTime.Now, "TimeOfDay.Hours");
Of course, you'll need to add a reference to the System.Web assembly, but this probably isn't a big deal.

The method to call has changed in .NET Standard (as of 1.6). Also we can use C# 6's null conditional operator.
using System.Reflection;
public static object GetPropValue(object src, string propName)
{
return src.GetType().GetRuntimeProperty(propName)?.GetValue(src);
}

The below method works perfect for me:
class MyClass {
public string prop1 { set; get; }
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
}
To get the property value:
MyClass t1 = new MyClass();
...
string value = t1["prop1"].ToString();
To set the property value:
t1["prop1"] = value;

public static List<KeyValuePair<string, string>> GetProperties(object item) //where T : class
{
var result = new List<KeyValuePair<string, string>>();
if (item != null)
{
var type = item.GetType();
var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var pi in properties)
{
var selfValue = type.GetProperty(pi.Name).GetValue(item, null);
if (selfValue != null)
{
result.Add(new KeyValuePair<string, string>(pi.Name, selfValue.ToString()));
}
else
{
result.Add(new KeyValuePair<string, string>(pi.Name, null));
}
}
}
return result;
}
This is a way to get all properties with their values in a List.

Using PropertyInfo of the System.Reflection namespace. Reflection compiles just fine no matter what property we try to access. The error will come up during run-time.
public static object GetObjProperty(object obj, string property)
{
Type t = obj.GetType();
PropertyInfo p = t.GetProperty("Location");
Point location = (Point)p.GetValue(obj, null);
return location;
}
It works fine to get the Location property of an object
Label1.Text = GetObjProperty(button1, "Location").ToString();
We'll get the Location : {X=71,Y=27}
We can also return location.X or location.Y on the same way.

public class YourClass
{
//Add below line in your class
public object this[string propertyName] => GetType().GetProperty(propertyName)?.GetValue(this, null);
public string SampleProperty { get; set; }
}
//And you can get value of any property like this.
var value = YourClass["SampleProperty"];

The following code is a Recursive method for displaying the entire hierarchy of all of the Property Names and Values contained in an object's instance. This method uses a simplified version of AlexD's GetPropertyValue() answer above in this thread. Thanks to this discussion thread, I was able to figure out how to do this!
For example, I use this method to show an explosion or dump of all of the properties in a WebService response by calling the method as follows:
PropertyValues_byRecursion("Response", response, false);
public static object GetPropertyValue(object srcObj, string propertyName)
{
if (srcObj == null)
{
return null;
}
PropertyInfo pi = srcObj.GetType().GetProperty(propertyName.Replace("[]", ""));
if (pi == null)
{
return null;
}
return pi.GetValue(srcObj);
}
public static void PropertyValues_byRecursion(string parentPath, object parentObj, bool showNullValues)
{
/// Processes all of the objects contained in the parent object.
/// If an object has a Property Value, then the value is written to the Console
/// Else if the object is a container, then this method is called recursively
/// using the current path and current object as parameters
// Note: If you do not want to see null values, set showNullValues = false
foreach (PropertyInfo pi in parentObj.GetType().GetTypeInfo().GetProperties())
{
// Build the current object property's namespace path.
// Recursion extends this to be the property's full namespace path.
string currentPath = parentPath + "." + pi.Name;
// Get the selected property's value as an object
object myPropertyValue = GetPropertyValue(parentObj, pi.Name);
if (myPropertyValue == null)
{
// Instance of Property does not exist
if (showNullValues)
{
Console.WriteLine(currentPath + " = null");
// Note: If you are replacing these Console.Write... methods callback methods,
// consider passing DBNull.Value instead of null in any method object parameters.
}
}
else if (myPropertyValue.GetType().IsArray)
{
// myPropertyValue is an object instance of an Array of business objects.
// Initialize an array index variable so we can show NamespacePath[idx] in the results.
int idx = 0;
foreach (object business in (Array)myPropertyValue)
{
if (business == null)
{
// Instance of Property does not exist
// Not sure if this is possible in this context.
if (showNullValues)
{
Console.WriteLine(currentPath + "[" + idx.ToString() + "]" + " = null");
}
}
else if (business.GetType().IsArray)
{
// myPropertyValue[idx] is another Array!
// Let recursion process it.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
else if (business.GetType().IsSealed)
{
// Display the Full Property Path and its Value
Console.WriteLine(currentPath + "[" + idx.ToString() + "] = " + business.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
idx++;
}
}
else if (myPropertyValue.GetType().IsSealed)
{
// myPropertyValue is a simple value
Console.WriteLine(currentPath + " = " + myPropertyValue.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath, myPropertyValue, showNullValues);
}
}
}

public static TValue GetFieldValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetFields(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.FieldType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}
public static TValue GetPropertyValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetProperties(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.PropertyType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}

Dim NewHandle As YourType = CType(Microsoft.VisualBasic.CallByName(ObjectThatContainsYourVariable, "YourVariableName", CallType), YourType)

Here is another way to find a nested property that doesn't require the string to tell you the nesting path. Credit to Ed S. for the single property method.
public static T FindNestedPropertyValue<T, N>(N model, string propName) {
T retVal = default(T);
bool found = false;
PropertyInfo[] properties = typeof(N).GetProperties();
foreach (PropertyInfo property in properties) {
var currentProperty = property.GetValue(model, null);
if (!found) {
try {
retVal = GetPropValue<T>(currentProperty, propName);
found = true;
} catch { }
}
}
if (!found) {
throw new Exception("Unable to find property: " + propName);
}
return retVal;
}
public static T GetPropValue<T>(object srcObject, string propName) {
return (T)srcObject.GetType().GetProperty(propName).GetValue(srcObject, null);
}

You never mention what object you are inspecting, and since you are rejecting ones that reference a given object, I will assume you mean a static one.
using System.Reflection;
public object GetPropValue(string prop)
{
int splitPoint = prop.LastIndexOf('.');
Type type = Assembly.GetEntryAssembly().GetType(prop.Substring(0, splitPoint));
object obj = null;
return type.GetProperty(prop.Substring(splitPoint + 1)).GetValue(obj, null);
}
Note that I marked the object that is being inspected with the local variable obj. null means static, otherwise set it to what you want. Also note that the GetEntryAssembly() is one of a few available methods to get the "running" assembly, you may want to play around with it if you are having a hard time loading the type.

Have a look at the Heleonix.Reflection library. You can get/set/invoke members by paths, or create a getter/setter (lambda compiled into a delegate) which is faster than reflection. For example:
var success = Reflector.Get(DateTime.Now, null, "Date.Year", out int value);
Or create a getter once and cache for reuse (this is more performant but might throw NullReferenceException if an intermediate member is null):
var getter = Reflector.CreateGetter<DateTime, int>("Date.Year", typeof(DateTime));
getter(DateTime.Now);
Or if you want to create a List<Action<object, object>> of different getters, just specify base types for compiled delegates (type conversions will be added into compiled lambdas):
var getter = Reflector.CreateGetter<object, object>("Date.Year", typeof(DateTime));
getter(DateTime.Now);

Although the original question was about how to get the value of the property using only a single string as the parameter, it makes a lot of sense here to use an Expression rather than simply a string to ensure that the caller never uses a hard coded property name. Here is a one line version with usage:
public static class Utils
...
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
=> (TVal)((x.Body as MemberExpression)?.Member as PropertyInfo)!.GetValue(t);
...
var val = Utils.GetPropertyValue(foo, p => p.Bar);
Here is a slightly better version in terms of readability a error handling:
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
{
var m = (x.Body as MemberExpression)?.Member;
var p = m as PropertyInfo;
if (null == p)
throw new ArgumentException($"Unknown property: {typeof(T).Name}.{(m?.Name??"???")}");
return (TVal)p.GetValue(t);
}
In short you pass in a lambda expression reading a property. The body of the lambda - the part on the right of the fat arrow - is a member expression from which you can get the member name and which you can cast to a PropertyInfo, provided the member is actually a Property and not, for instance, a method.
In the short version, the null forgiving operator - the ! in the expression - tells the compiler that the PropertyInfo will not be null. This is a big lie and you will get a NullReferenceException at runtime. The longer version gives you the name of the property if it manages to get it.
PS: Thanks to Oleg G. for the initial version of this code :)

shorter way ....
var a = new Test { Id = 1 , Name = "A" , date = DateTime.Now};
var b = new Test { Id = 1 , Name = "AXXX", date = DateTime.Now };
var compare = string.Join("",a.GetType().GetProperties().Select(x => x.GetValue(a)).ToArray())==
string.Join("",b.GetType().GetProperties().Select(x => x.GetValue(b)).ToArray());

jheddings and AlexD both wrote excellent answers on how to resolve property strings. I'd like to throw mine in the mix, since I wrote a dedicated library exactly for that purpose.
Pather.CSharp's main class is Resolver. Per default it can resolve properties, array and dictionary entries.
So, for example, if you have an object like this
var o = new { Property1 = new { Property2 = "value" } };
and want to get Property2, you can do it like this:
IResolver resolver = new Resolver();
var path = "Property1.Property2";
object result = r.Resolve(o, path);
//=> "value"
This is the most basic example of the paths it can resolve. If you want to see what else it can, or how you can extend it, just head to its Github page.

Here's what I got based on other answers. A little overkill on getting so specific with the error handling.
public static T GetPropertyValue<T>(object sourceInstance, string targetPropertyName, bool throwExceptionIfNotExists = false)
{
string errorMsg = null;
try
{
if (sourceInstance == null || string.IsNullOrWhiteSpace(targetPropertyName))
{
errorMsg = $"Source object is null or property name is null or whitespace. '{targetPropertyName}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
Type returnType = typeof(T);
Type sourceType = sourceInstance.GetType();
PropertyInfo propertyInfo = sourceType.GetProperty(targetPropertyName, returnType);
if (propertyInfo == null)
{
errorMsg = $"Property name '{targetPropertyName}' of type '{returnType}' not found for source object of type '{sourceType}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
return (T)propertyInfo.GetValue(sourceInstance, null);
}
catch(Exception ex)
{
errorMsg = $"Problem getting property name '{targetPropertyName}' from source instance.";
Log.Error(errorMsg, ex);
if (throwExceptionIfNotExists)
throw;
}
return default(T);
}

Here is my solution. It works also with COM objects and allows to access collection/array items from COM objects.
public static object GetPropValue(this object obj, string name)
{
foreach (string part in name.Split('.'))
{
if (obj == null) { return null; }
Type type = obj.GetType();
if (type.Name == "__ComObject")
{
if (part.Contains('['))
{
string partWithoundIndex = part;
int index = ParseIndexFromPropertyName(ref partWithoundIndex);
obj = Versioned.CallByName(obj, partWithoundIndex, CallType.Get, index);
}
else
{
obj = Versioned.CallByName(obj, part, CallType.Get);
}
}
else
{
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
}
return obj;
}
private static int ParseIndexFromPropertyName(ref string name)
{
int index = -1;
int s = name.IndexOf('[') + 1;
int e = name.IndexOf(']');
if (e < s)
{
throw new ArgumentException();
}
string tmp = name.Substring(s, e - s);
index = Convert.ToInt32(tmp);
name = name.Substring(0, s - 1);
return index;
}

Whenever you want to loop over all properties in on an object and then use each value of the property must use this piece of code:
foreach (var property in request.GetType().GetProperties())
{
var valueOfProperty = property.GetValue(properties, null);
}

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

Understanding/Getting symbol type? - c#

Related

How to use bracket notation to access model property inside the loop in c# [duplicate]

How to access property of object with a variable name [duplicate]

Enum get value by reference c# [duplicate]

Find which using directives are used in method

Get property value from string using reflection

Categories

Resources