Related
The parameter value I'm passing is:
"System.Runtime.Serialization.DataContractSerializer, System.Runtime.Serialization"
When I add the bool parameter to throw an exception I get a FileNotFoundException.
I can't find any documentation on why this wouldn't work. The only problems I can find related to this method involve callers not specifying the assembly name.
Also, my project has an assembly reference to System.Runtime.Serialization.
var type = Type.GetType("System.Runtime.Serialization.DataContractSerializer, System.Runtime.Serialization", true);
If you are trying to get the Type object that represents the DataContractSerializer, you can use the typeof operator:
Type type = typeof(System.Runtime.Serialization.DataContractSerializer);
This is the code (I've modified it for simplicity):
System.Reflection.Assembly asm = System.Reflection.Assembly.GetExecutingAssembly();
Type t = asm.GetType("OneSubClass");
System.Reflection.PropertyInfo pi = t.GetProperty("SubClassProperty");
After this code, asm is my application's exe, which has a half dozen or so classes inside it.
t is the type for one of those classes inside the exe.
pi is filled with the property info of the property within the class OneSubClass
When running my application, it creates instances for all these classes defined in the exe. Then the above code is executed. However, how do I get the actual value of the property?
If I try something like:
pi.GetValue(asm, null);
it gives me exception "object does not match target type" - I need an instance of the class I want the property from (which I'm not sure how to get - I only have asm)
You need an instance of the OneSubClass class. The class (and the type) itself is just a template - it has no values for any of its properties. Each instance of the type has values, and you pass the instance into GetValue:
pi.GetValue(instanceOfOneSubClass, null);
One way to create an instance is using Activator:
object myInstance = Activator.CreateInstance(typeof(OneSubClass));
But that is basically the equivalent of calling new OneSubClass(), so unless you know the default constructor will do exactly what you're expecting here, that's not always very useful.
When running my application, it creates instances for all these classes defined in the exe.
I'm not exactly sure what this means. Are you saying somewhere there is already a created instance and you need to somehow get a handle to it?
t is only a type, not an instance of that type.
You first have to create an instance of that type like this:
object asmInstance = Activator.CreateInstance(t);
then get the value on that instance
pi.GetValue(asmInstance, null);
You are triying to get the property from the Assembly class you are instantiating.
To retrieve a value from an object, you need the reference to that object:
object GetValueFromClass(object Class)
{
System.Reflection.Assembly asm = System.Reflection.Assembly.GetExecutingAssembly();
Type t = asm.GetType("OneSubClass");
System.Reflection.PropertyInfo pi = t.GetProperty("SubClassProperty");
return pi.GetValue(Class, null);
}
This code:
Type.GetType("namespace.a.b.ClassName")
returns null.
I have in the usings:
using namespace.a.b;
The type exists, it's in a different class library, and I need to get it by it's name given as string.
Type.GetType("namespace.qualified.TypeName") only works when the type is found in either mscorlib.dll or the currently executing assembly.
If neither of those things are true, you'll need an assembly-qualified name:
Type.GetType("namespace.qualified.TypeName, Assembly.Name")
You can also get the type without assembly qualified name but with the dll name also, for example:
Type myClassType = Type.GetType("TypeName,DllName");
I had the same situation and it worked for me. I needed an object of type "DataModel.QueueObject" and had a reference to "DataModel" so I got the type as follows:
Type type = Type.GetType("DataModel.QueueObject,DataModel");
The second string after the comma is the reference name (dll name).
Try this method.
public static Type GetType(string typeName)
{
var type = Type.GetType(typeName);
if (type != null) return type;
foreach (var a in AppDomain.CurrentDomain.GetAssemblies())
{
type = a.GetType(typeName);
if (type != null)
return type;
}
return null;
}
If the assembly is part of the build of an ASP.NET application, you can use the BuildManager class:
using System.Web.Compilation
...
BuildManager.GetType(typeName, false);
Dictionary<string, Type> typeCache;
...
public static bool TryFindType(string typeName, out Type t) {
lock (typeCache) {
if (!typeCache.TryGetValue(typeName, out t)) {
foreach (Assembly a in AppDomain.CurrentDomain.GetAssemblies()) {
t = a.GetType(typeName);
if (t != null)
break;
}
typeCache[typeName] = t; // perhaps null
}
}
return t != null;
}
if your class is not in current assambly you must give qualifiedName and this code shows how to get qualifiedname of class
string qualifiedName = typeof(YourClass).AssemblyQualifiedName;
and then you can get type with qualifiedName
Type elementType = Type.GetType(qualifiedName);
As Type.GetType(String) need the Type.AssemblyQualifiedName you should use Assembly.CreateQualifiedName(String, String).
string typeName = "MyNamespace.MyClass"; // Type.FullName
string assemblyName = "MyAssemblyName"; // MyAssembly.FullName or MyAssembly.GetName().Name
string assemblyQualifiedName = Assembly.CreateQualifiedName(assemblyName , typeName);
Type myClassType = Type.GetType(assemblyQualifiedName);
The Version, Culture and PublicKeyToken are not required for assemblyName that's why you can use MyAssembly.GetName().Name.
About Type.GetType(String) :
If the type is in the currently executing
assembly or in Mscorlib.dll, it is sufficient to supply the type name
qualified by its namespace.
When I have only the class name I use this:
Type obj = AppDomain.CurrentDomain.GetAssemblies().SelectMany(t => t.GetTypes()).Where(t => String.Equals(t.Name, _viewModelName, StringComparison.Ordinal)).First();
If it's a nested Type, you might be forgetting to transform a . to a +
Regardless, typeof( T).FullName will tell you what you should be saying
EDIT: BTW the usings (as I'm sure you know) are only directives to the compiler at compile time and cannot thus have any impact on the API call's success. (If you had project or assembly references, that could potentially have had influence - hence the information isnt useless, it just takes some filtering...)
I am opening user controls depending on what user controls the user have access to specified in a database. So I used this method to get the TypeName...
Dim strType As String = GetType(Namespace.ClassName).AssemblyQualifiedName.ToString
Dim obj As UserControl = Activator.CreateInstance(Type.GetType(strType))
So now one can use the value returned in strType to create an instance of that object.
If the assembly is referenced and the Class visible :
typeof(namespace.a.b.ClassName)
GetType returns null because the type is not found, with typeof, the compiler may help you to find out the error.
Try using the full type name that includes the assembly info, for example:
string typeName = #"MyCompany.MyApp.MyDomain.MyClass, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null";
Type myClassType = Type.GetType(typeName);
I had the same situation when I was using only the the namesspace.classname to get the type of a class in a different assembly and it would not work. Only worked when I included the assembly info in my type string as shown above.
Make sure that the comma is directly after the fully qualified name
typeof(namespace.a.b.ClassName, AssemblyName)
As this wont work
typeof(namespace.a.b.ClassName ,AssemblyName)
I was stumped for a few days on this one
For me, a "+" was the key!
This is my class(it is a nested one) :
namespace PortalServices
{
public class PortalManagement : WebService
{
public class Merchant
{}
}
}
and this line of code worked:
Type type = Type.GetType("PortalServices.PortalManagement+Merchant");
This solution above seems to be the best to me, but it didn't work for me, so I did it as follows:
AssemblyName assemblyName = AssemblyName.GetAssemblyName(HttpContext.Current.Server.MapPath("~\\Bin\\AnotherAssembly.dll"));
string typeAssemblyQualifiedName = string.Join(", ", "MyNamespace.MyType", assemblyName.FullName);
Type myType = Type.GetType(typeAssemblyQualifiedName);
The precondition is that you know the path of the assembly. In my case I know it because this is an assembly built from another internal project and its included in our project's bin folder.
In case it matters I am using Visual Studio 2013, my target .NET is 4.0. This is an ASP.NET project, so I am getting absolute path via HttpContext. However, absolute path is not a requirement as it seems from MSDN on AssemblyQualifiedNames
I cheated. Since the types I want to create (by name) are all in In a dll I control, I just put a static method in the dll in the assembly that takes a simple name, and calls type.GetType from that context and returns the result.
The original purpose was so that the type could be specified by name in configuration data. I've since change the code so that the user specified a format to process. The format handler classes implement a interface that determines if the type can parse the specified format. I then use reflection to find types that implement the interface, and find one that handles the format. So now the configuration specifies a format name, a not a specific type. The reflection code can look at adjacent dlls and load, them so I have a sort poor man's plug-in architecture.
Very late reply, but if anyone is dealing with this a decade later:
There is a very, very small chance that your class in Visual Studio has a Build Action set to "Content" instead of "Compile".
Click on your class in Solution Explorer, then look at the properties.
Check that Build Action is "Compile", not "Content".
I'm completely new to reflection and I'm trying to call a class name from a db record and then load the class and run it but I'm pulling my hair out on where I'm going wrong, its probably something really silly I'm missing.
As an example I have my class in a different project and scripts folder, then call the name of it from the db record.
className = String.Format("Utilities.Scripts.{0}", script.ScriptClass);
Then in my main program I have
// Get a type from the string
Type type = Type.GetType(className);
// Create an instance of that type
Object obj = Activator.CreateInstance(type);
// Retrieve the method you are looking for
MethodInfo methodInfo = type.GetMethod("start");
// Invoke the method on the instance we created above
methodInfo.Invoke(obj, null);
But I am getting the error as when debugging I can see my details passed into the GetType(className) but nothing goes through to the type and as such into the obj where it is erroring.
You need to supply the Assembly Qualified Name of the type (as mentioned here) since the class is in a different project. Also, make sure that the assembly you are trying to load the type from is either in the same folder as the assembly trying to load it, or in the GAC.
For a class defined as below:
namespace Foo.Bar
{
public class Class1
{
}
}
The full class name is Foo.Bar.Class1. The assembly qualified name also specifies the full name of the assembly, as in Foo.Bar.Class1, Foo.Bar, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35. You can find the Assembly Qualified Name of your type with somthing like:
Console.WriteLine(typeof(Foo.Bar.Class1).AssemblyQualifiedName)
The problem is in this line:
Type type = Type.GetType(className);
In that this particular overload of the method will not throw an exception when the type cannot be resolved. Instead use this overload which takes 2 booleans, one of which being throwOnError. Pass true for this parameter and you will get an exception which should help you debug why your type cannnot be resolved from the string you pass in.
I suspect you need a class name and assembly name
Utilities.Scripts.SomeClass, SomeAssemblyName
This code:
Type.GetType("namespace.a.b.ClassName")
returns null.
I have in the usings:
using namespace.a.b;
The type exists, it's in a different class library, and I need to get it by it's name given as string.
Type.GetType("namespace.qualified.TypeName") only works when the type is found in either mscorlib.dll or the currently executing assembly.
If neither of those things are true, you'll need an assembly-qualified name:
Type.GetType("namespace.qualified.TypeName, Assembly.Name")
You can also get the type without assembly qualified name but with the dll name also, for example:
Type myClassType = Type.GetType("TypeName,DllName");
I had the same situation and it worked for me. I needed an object of type "DataModel.QueueObject" and had a reference to "DataModel" so I got the type as follows:
Type type = Type.GetType("DataModel.QueueObject,DataModel");
The second string after the comma is the reference name (dll name).
Try this method.
public static Type GetType(string typeName)
{
var type = Type.GetType(typeName);
if (type != null) return type;
foreach (var a in AppDomain.CurrentDomain.GetAssemblies())
{
type = a.GetType(typeName);
if (type != null)
return type;
}
return null;
}
If the assembly is part of the build of an ASP.NET application, you can use the BuildManager class:
using System.Web.Compilation
...
BuildManager.GetType(typeName, false);
Dictionary<string, Type> typeCache;
...
public static bool TryFindType(string typeName, out Type t) {
lock (typeCache) {
if (!typeCache.TryGetValue(typeName, out t)) {
foreach (Assembly a in AppDomain.CurrentDomain.GetAssemblies()) {
t = a.GetType(typeName);
if (t != null)
break;
}
typeCache[typeName] = t; // perhaps null
}
}
return t != null;
}
if your class is not in current assambly you must give qualifiedName and this code shows how to get qualifiedname of class
string qualifiedName = typeof(YourClass).AssemblyQualifiedName;
and then you can get type with qualifiedName
Type elementType = Type.GetType(qualifiedName);
As Type.GetType(String) need the Type.AssemblyQualifiedName you should use Assembly.CreateQualifiedName(String, String).
string typeName = "MyNamespace.MyClass"; // Type.FullName
string assemblyName = "MyAssemblyName"; // MyAssembly.FullName or MyAssembly.GetName().Name
string assemblyQualifiedName = Assembly.CreateQualifiedName(assemblyName , typeName);
Type myClassType = Type.GetType(assemblyQualifiedName);
The Version, Culture and PublicKeyToken are not required for assemblyName that's why you can use MyAssembly.GetName().Name.
About Type.GetType(String) :
If the type is in the currently executing
assembly or in Mscorlib.dll, it is sufficient to supply the type name
qualified by its namespace.
When I have only the class name I use this:
Type obj = AppDomain.CurrentDomain.GetAssemblies().SelectMany(t => t.GetTypes()).Where(t => String.Equals(t.Name, _viewModelName, StringComparison.Ordinal)).First();
If it's a nested Type, you might be forgetting to transform a . to a +
Regardless, typeof( T).FullName will tell you what you should be saying
EDIT: BTW the usings (as I'm sure you know) are only directives to the compiler at compile time and cannot thus have any impact on the API call's success. (If you had project or assembly references, that could potentially have had influence - hence the information isnt useless, it just takes some filtering...)
I am opening user controls depending on what user controls the user have access to specified in a database. So I used this method to get the TypeName...
Dim strType As String = GetType(Namespace.ClassName).AssemblyQualifiedName.ToString
Dim obj As UserControl = Activator.CreateInstance(Type.GetType(strType))
So now one can use the value returned in strType to create an instance of that object.
If the assembly is referenced and the Class visible :
typeof(namespace.a.b.ClassName)
GetType returns null because the type is not found, with typeof, the compiler may help you to find out the error.
Try using the full type name that includes the assembly info, for example:
string typeName = #"MyCompany.MyApp.MyDomain.MyClass, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null";
Type myClassType = Type.GetType(typeName);
I had the same situation when I was using only the the namesspace.classname to get the type of a class in a different assembly and it would not work. Only worked when I included the assembly info in my type string as shown above.
Make sure that the comma is directly after the fully qualified name
typeof(namespace.a.b.ClassName, AssemblyName)
As this wont work
typeof(namespace.a.b.ClassName ,AssemblyName)
I was stumped for a few days on this one
For me, a "+" was the key!
This is my class(it is a nested one) :
namespace PortalServices
{
public class PortalManagement : WebService
{
public class Merchant
{}
}
}
and this line of code worked:
Type type = Type.GetType("PortalServices.PortalManagement+Merchant");
This solution above seems to be the best to me, but it didn't work for me, so I did it as follows:
AssemblyName assemblyName = AssemblyName.GetAssemblyName(HttpContext.Current.Server.MapPath("~\\Bin\\AnotherAssembly.dll"));
string typeAssemblyQualifiedName = string.Join(", ", "MyNamespace.MyType", assemblyName.FullName);
Type myType = Type.GetType(typeAssemblyQualifiedName);
The precondition is that you know the path of the assembly. In my case I know it because this is an assembly built from another internal project and its included in our project's bin folder.
In case it matters I am using Visual Studio 2013, my target .NET is 4.0. This is an ASP.NET project, so I am getting absolute path via HttpContext. However, absolute path is not a requirement as it seems from MSDN on AssemblyQualifiedNames
I cheated. Since the types I want to create (by name) are all in In a dll I control, I just put a static method in the dll in the assembly that takes a simple name, and calls type.GetType from that context and returns the result.
The original purpose was so that the type could be specified by name in configuration data. I've since change the code so that the user specified a format to process. The format handler classes implement a interface that determines if the type can parse the specified format. I then use reflection to find types that implement the interface, and find one that handles the format. So now the configuration specifies a format name, a not a specific type. The reflection code can look at adjacent dlls and load, them so I have a sort poor man's plug-in architecture.
Very late reply, but if anyone is dealing with this a decade later:
There is a very, very small chance that your class in Visual Studio has a Build Action set to "Content" instead of "Compile".
Click on your class in Solution Explorer, then look at the properties.
Check that Build Action is "Compile", not "Content".