Develop Reference

Using reflection to iterate a class properties that has nested classes

I found this answer here at SO, Get nested property values through reflection C#, though when I run it in my case, it also tries to dump/recurse on e.g. a string's property, like Name, and when, it throws an exception.
My classes look like this
public class MyModels
{
public int Id { get; set; }
public DateTime EditDate { get; set; }
public string EditBy { get; set; }
}
public class Person
{
public string Name { get; set; }
}
public class Organization
{
public Person Person { get; set; }
public Organization()
{
Person = new Person();
}
public string Name { get; set; }
}
public class Company : MyModels
{
public Organization Organization { get; set; }
public Company()
{
Organization = new Organization();
}
public string Description { get; set; }
}
And here's the code from the linked answer
var objtree = "";
void DumpObjectTree(object propValue, int level = 0)
{
if (propValue == null)
return;
var childProps = propValue.GetType().GetProperties();
foreach (var prop in childProps)
{
var name = prop.Name;
var value = prop.GetValue(propValue, null);
// add some left padding to make it look like a tree
objtree += ("".PadLeft(level * 4, ' ') + $"{name} = {value}") + Environment.NewLine;
// call again for the child property
DumpObjectTree(value, level + 1);
}
}
DumpObjectTree(itemData);
What I want is to iterate all the properties and check their value.
When I run the above code sample:
it first finds Organization, and recurse
at 1st level it finds Person, and recurse
at 2nd level if finds Name, and recurse
at 3rd level it throws an exception when it tries to GetValue for Name
If I remove my nested classes, and run it:
it first finds Description, and recurse
at 1st level it throws an exception when it tries to GetValue for Description
How do I make it to not try to dump/recurse on properties of type string, datetime, etc., like e.g. Name, Description?
The exception message says: "Parameter count mismatch."
As a note , the expected output/content in the objtree variable is e.g.
Organization = MyNameSpace.Models.Organization
Person = MyNameSpace.Models.Person
Name = TestName
Name = TestCompany
Description = Some info about the company...
Id = 1
EditDate = 31/08/2019
EditBy = user#domain.com

The reason for the exception is that string has a property named Chars. You normally don't see this property, because it's the indexer used when you do something like char c = myString[0];.
This property obviously needs a paramter (the index), and since you don't provide one, an exception is thrown.
To filter the types you don't want to recurse you need to extend the first line in the method. For example
if (propValue == null) return;
if (propValue.GetType().Assembly != Assembly.GetExecutingAssembly())
return;
This will only recurse through types declared in your assembly. If you want special filtering you need to adjust it.
Your current specification ("of type string, datetime etc") is not specific enough to give an exact solution, but I think the idea is clear.
Note that this won't prevent an exception to be raised if you declare an indexer in your own classes. So a better way might be to check for indexers directly:
foreach (var prop in childProps)
{
if (prop.GetIndexParameters().Any()) continue;
Second note: The current code has another flaw: You should keep track of which types you already dumped and abort the recursion when you come across a type the second time. That's possibly the reason for the exception at DateTime. A DateTime has a Date property, which is - hurray - of type DateTime. And so your objtree string grows infinitly until an OutOfMemoryException or StackOverflowException is thrown.

You need to skip recursion when:
Property is a value type
Property is a string
Property value contains reference to the object from the previous recursion level (ie, ParentObject) so that you don't get a stack overflow exception
Edit: Also when property is a collection type. If you want to get creative, you can have your recursor iterate through each object in the collection and then recurse through those
This PropertyInfo recursor seems to do the trick.
[Flags]
public enum PropertyRecursionOverflowProtectionType
{
SkipSameReference,
SkipSameType
}
public class PropertyRecursionBot
{
public object ParentObject { get; set; }
public object CurrentObject { get; set; }
public PropertyInfo PropertyInfo { get; set; }
public Type ParentType { get; set; }
public int Level { get; set; }
}
public static IEnumerable<PropertyRecursionBot> GetAllProperties(object entity,
PropertyRecursionOverflowProtectionType overflowProtectionType = PropertyRecursionOverflowProtectionType.SkipSameReference)
{
var type = entity.GetType();
var bot = new PropertyRecursionBot { CurrentObject = entity };
IEnumerable<PropertyRecursionBot> GetAllProperties(PropertyRecursionBot innerBot, PropertyInfo[] properties)
{
var currentParentObject = innerBot.ParentObject;
var currentObject = innerBot.CurrentObject;
foreach (var pi in properties)
{
innerBot.PropertyInfo = pi;
var obj = pi.GetValue(currentObject);
innerBot.CurrentObject = obj;
//Return the property and value only if it's a value type or string
if (pi.PropertyType == typeof(string) || !pi.PropertyType.IsClass)
{
yield return innerBot;
continue;
}
//This overflow protection check will prevent stack overflow if your object has bidirectional navigation
else if (innerBot.CurrentObject == null ||
(overflowProtectionType.HasFlag(PropertyRecursionOverflowProtectionType.SkipSameReference) && innerBot.CurrentObject == currentParentObject) ||
(overflowProtectionType.HasFlag(PropertyRecursionOverflowProtectionType.SkipSameType) && innerBot.CurrentObject.GetType() == currentParentObject?.GetType()))
{
continue;
}
innerBot.Level++;
innerBot.ParentObject = currentObject;
foreach (var innerPi in GetAllProperties(innerBot, pi.PropertyType.GetProperties()))
{
yield return innerPi;
}
innerBot.Level--;
innerBot.ParentObject = currentParentObject;
innerBot.CurrentObject = obj;
}
}
foreach (var pi in GetAllProperties(bot, type.GetProperties()))
{
yield return pi;
}
}
Use it like this:
public class RecursionTest
{
public string StringValue { get; set; }
public int IntValue { get; set; }
public RecursionTest Test { get; set; }
public RecursionTest ParentTest { get; set; }
}
var rec1 = new RecursionTest
{
IntValue = 20,
StringValue = Guid.NewGuid().ToString()
};
rec1.Test = new RecursionTest
{
IntValue = 30,
StringValue = Guid.NewGuid().ToString(),
ParentTest = rec1
};
rec1.Test.Test = new RecursionTest
{
IntValue = 40,
StringValue = Guid.NewGuid().ToString(),
ParentTest = rec1.Test
};
foreach (var bot in GetAllProperties(rec1, PropertyRecursionOverflowProtectionType.SkipSameReference))
{
Console.WriteLine($"{new string(' ', bot.Level * 2)}{bot.PropertyInfo.Name}: {bot.CurrentObject}");
}

Updating Custom Class in List<T>

I am trying to update a List which is a List of Interfaces to concrete classes.
I add to the List each Market type i am interested in, for this Example these Markets are A and B
I loop over all the markets, (sample provided with 3 markets A B & C, we are only interested in A and B) And determine which is of interest to us.
Once found we pass this to an extraction method too do its work and create an instance of the Correct Market_ class type.
This all works fine, but when i try to update the list with the Updates it does not get reflected in the List.
Code below, any Suggestions?
Thanks
public class Test
{
public Test()
{
TheMarkets MarketsToUpdate = new TheMarkets();
List<SpecificCompanyMarket> lstMarks = new List<SpecificCompanyMarket>();
lstMarks.Add(new SpecificCompanyMarket(1234, "A", "Some HTML DATA HERE"));
lstMarks.Add(new SpecificCompanyMarket(5874, "B", "Some HTML DATA HERE"));
lstMarks.Add(new SpecificCompanyMarket(2224, "C", "Some HTML DATA HERE"));
foreach (var item in lstMarks)
{
if (MarketsToUpdate.IsMarketWeAreInterestedIn(item.MarketName))
{
ITheMarkets MarkToUpdate = ExtractMarketData(item);
var obj = MarketsToUpdate.MarketsWeAreInterestedIn.FirstOrDefault(x => x.MarketName() == "A");
if (obj != null)
{
obj = MarkToUpdate;
}
}
}
//Look At MarketsToUpdate Now and the item has not changed, still original values
//I was expecting to see the new values for the fields in A, not the default 0's
}
public ITheMarkets ExtractMarketData(SpecificCompanyMarket item)
{
ITheMarkets market = null;
if (item.MarketName.ToUpper() == "A")
{
Market_A marketType = new Market_A();
marketType.SomeValue1 = 123;
marketType.SomeValue2 = 158253;
market = marketType;
}
//Other Market extractions here
return market;
}
}
public class SpecificCompanyMarket
{
public int MarketId { get; set; }
public string MarketName { get; set; }
public string MarketDataHTML { get; set; }
public SpecificCompanyMarket(int MID, string MName, string MData)
{
MarketId = MID;
MarketName = MName;
MarketDataHTML = MData;
}
}
public class TheMarkets
{
public List<ITheMarkets> MarketsWeAreInterestedIn = new List<ITheMarkets>();
public TheMarkets()
{
Market_A A = new Market_A();
Market_B B = new Market_B();
MarketsWeAreInterestedIn.Add(A);
MarketsWeAreInterestedIn.Add(B);
}
public bool IsMarketWeAreInterestedIn(string strMarketName)
{
bool blnRetVal = false;
foreach (var item in MarketsWeAreInterestedIn)
{
if (item.MarketName().ToUpper().Trim().Equals(strMarketName.ToUpper().Trim()))
{
blnRetVal = true;
break;
}
}
return blnRetVal;
}
}
public interface ITheMarkets
{
string MarketName();
}
public class Market_A : ITheMarkets
{
public string LabelType { get; private set; }
public double SomeValue1 { get; set; }
public double SomeValue2 { get; set; }
public double SomeValue3 { get; set; }
public Market_A()
{
LabelType = "A";
}
public string MarketName()
{
return LabelType;
}
}
public class Market_B : ITheMarkets
{
public string LabelType { get; private set; }
public List<string> SomeList { get; set; }
public double SomeValue { get; set; }
public Market_B()
{
LabelType = "B";
}
public string MarketName()
{
return LabelType;
}
}

This is a short example to get you going. Loop through your list, find the object you want to update, create a new object of that type and then find the original objects index in the list and overwrite it in place. You are essentially just replacing the object in the list with a new one not mutating the existing one.
foreach (var item in lstMarks)
{
//your code to get an object with data to update
var yourObjectToUpdate = item.GetTheOneYouWant();
//make updates
yourObjectToUpdate.SomeProperty = "New Value";
int index = lstMarks.IndexOf(item);
lstMarks[index] = yourObjectToUpdate;
}

You are extracting an obj from marketWeAreInterestedIn list using LINQ's firstOrDefault extension. This is a new object and not a reference to the obj in that list. Therefore, no updates will be reflected in the object inside that list. Try using 'indexof'

You are not storing "list of interfaces" in your list. List<T> stores an array of pointers to objects that support T interface. Once you enumerate (with Linq in your case) your list, you copy a pointer from list, which is not associated with list itself in any way. It is just a pointer to your instance.
To do what you want, you will have to build new list while enumerating the original one, adding objects to it, according to your needs, so the second list will be based on the first one but with changes applied that you need.
You can also replace specific instance at specific index instead of building new list in your code, but to do this you will need to enumerate your list with for loop and know an index for each item:
list[index] = newvalue;
But there is a third solution to update list item directly by Proxying them. This is an example
class ItemProxy : T { public T Value { get; set; } }
var list = new List<ItemProxy<MyClass>>();
list.Insert(new ItemProxy { Value = new MyClass() });
list.Insert(new ItemProxy { Value = new MyClass() });
list.Insert(new ItemProxy { Value = new MyClass() });
foreach(var item in list)
if(item // ...)
item.Value = new MyClass(); // done, pointer in the list is updated.
Third is the best case for perfomance, but it will be better to use this proxying class for something more than just proxying.

compare properties in classes of list in class

What I've got are two classes which each contain Lists of Classes with propperties of different types. The first list is an updated version of the second and i need to find all differences (deleted/added classes in lists and updated classes).
public class ClassOfKb
{
public List<Data> KbData {get;set;}
public List<Info> KbInfo {get;set;}
}
class Data
{
public Guid ID {get;set}
public byte[] file {get;set}
public string name {get;set}
}
class Info
{
public Guid ID {get;set}
public string text {get;set}
public DateTime date {get;set}
}
ClassOfKb KbA = new ClassOfKb();
ClassOfKb KbB = new ClassOfKb();
first KbA and KbB will be filled from the same DataSet, then i delete, add and modify some of KbA Child-Classes.
now i need to compare KbA with KbB to find out where the differences are. i need the ID of deleted or added classes in KbA and the exact changes of modified Child-Classes properties. How would i do this? Preffered with Linq.

I suggest that create two comparers one for Data and one for Info
class DataComparer : IEqualityComparer<Data>
{
public bool Equals(Data x, Data y)
{
//logic to compare x to y and return true when they are equal
}
public int GetHashCode(Data d)
{
//logic to return a hash code
}
}
class InfoComparer : IEqualityComparer<Info>
{
public bool Equals(Info x, Info y)
{
//logic to compare x to y and return true when they are equal
}
public int GetHashCode(Info i)
{
//logic to return a hash code
}
}
The you can use Intersect and Except LINQ methods
IEnumerable<Data> DataInAandNotInB = KbA.KbData.Except(KbB.KbData,new DataComparer());
IEnumerable<Info> InfoInAandInB = KbA.KbInfo.Intersect(KbB.KbInfo,new InfoComparer ());

For simplicity, I skipped comparison of the byte array and DateTime data membes, only left the IDs and the string data members, but to add them you will need some small modification.
The test is very-very basic, but shows all three of the changes options:
static void Main(string[] args)
{
ClassOfKb KbA = new ClassOfKb();
ClassOfKb KbB = new ClassOfKb();
// Test data --------
Data data1 = new Data() { ID = Guid.NewGuid(), name = "111" };
Data data2 = new Data() { ID = Guid.NewGuid(), name = "222" };
Data data2_changed = new Data() { ID = data2.ID, name = "222_changed" };
Data data3 = new Data() { ID = Guid.NewGuid(), name = "333" };
Info info1 = new Info() { ID = Guid.NewGuid(), text = "aaa" };
Info info2 = new Info() { ID = Guid.NewGuid(), text = "bbb" };
Info info2_changed = new Info() { ID = info2.ID, text = "bbb_changed" };
Info info3 = new Info() { ID = Guid.NewGuid(), text = "ccc" };
KbA.KbData.Add(data1);
KbA.KbData.Add(data2);
KbA.KbInfo.Add(info1);
KbA.KbInfo.Add(info2);
KbB.KbData.Add(data2_changed);
KbB.KbData.Add(data3);
KbB.KbInfo.Add(info2_changed);
KbB.KbInfo.Add(info3);
// end of test data ---------
// here is the solution:
var indexes = Enumerable.Range(0, KbA.KbData.Count);
var deleted = from i in indexes
where !KbB.KbData.Select((n) => n.ID).Contains(KbA.KbData[i].ID)
select new
{
Name = KbA.KbData[i].name,
KbDataID = KbA.KbData[i].ID,
KbInfoID = KbA.KbInfo[i].ID
};
Console.WriteLine("deleted:");
foreach (var val in deleted)
{
Console.WriteLine(val.Name);
}
var added = from i in indexes
where !KbA.KbData.Select((n) => n.ID).Contains(KbB.KbData[i].ID)
select new
{
Name = KbB.KbData[i].name,
KbDataID = KbB.KbData[i].ID,
KbInfoID = KbB.KbInfo[i].ID
};
Console.WriteLine("added:");
foreach (var val in added)
{
Console.WriteLine(val.Name);
}
var changed = from i in indexes
from j in indexes
where KbB.KbData[i].ID == KbA.KbData[j].ID &&
(//KbB.KbData[i].file != KbA.KbData[j].file ||
KbB.KbData[i].name != KbA.KbData[j].name ||
//KbB.KbInfo[i].date != KbA.KbInfo[j].date ||
KbB.KbInfo[i].text != KbA.KbInfo[j].text
)
select new
{
Name = KbA.KbData[j].name,
KbDataID = KbA.KbData[j].ID,
KbInfoID = KbA.KbInfo[j].ID
};
Console.WriteLine("changed:");
foreach (var val in changed)
{
Console.WriteLine(val.Name);
}
Console.ReadLine();
}
}
public class ClassOfKb
{
public List<Data> KbData = new List<Data>();
public List<Info> KbInfo = new List<Info>();
}
public class Data
{
public Guid ID { get; set; }
public byte[] file { get; set; }
public string name { get; set; }
}
public class Info
{
public Guid ID { get; set; }
public string text { get; set; }
public DateTime date { get; set; }
}

Compare elements of an object resides in two list - one on one using LINQ

I'm trying to find out is there any better way other than Enumerable.Range in WHERE clause to compare object's elements one on one.
It could be a parallel since We're comparing one on one here.
For example: House.Windows[0].color != House1.Windows[0].color and then movenext to
House.Windows[1].color != House1.Windows[1].color and so on...
Type will be same in both list.
public class House
{
string HouseNmbr;
List<Window> windows;
}
public class Window
{
string WSize;
string WColor;
bool IsEnergyEff;
}
public static class MyMain
{
void Main()
{
House h1 = new House
{
HouseNmbr = "1",
windows = new List<Window> {
new Window {Wsize="1", WColor = "blue",IsEnergyEff = true},
new Window {Wsize="1", WColor = "black"},
new Window {Wsize="1", WColor = "red"}
}
};
House h2 = new House
{
HouseNmbr = "1",
windows = new List<Window> {
new Window {Wsize="2", WColor = "blue",IsEnergyEff = false},
new Window {Wsize="2", WColor = "black"}
}
};
//Find the diffs...
IEnumerable<House> updatesFromHouses = from id in h2 //Since h2 will have updates
join pd in h1
on id.HouseNmbr equals pd.HouseNmbr
select new House
{
windows = pd.windows.Where(
wn => Enumerable.Range(0, wn.windows.Count).All(ctr => wn.IsEnergyEff != id.windows[ctr].IsEnergyEff)
).ToList()
};
}
}

Use Enumerable.Zip if you are comparing one by one:
House.Windows.Zip(House1.Windows, (w, w1) => w.color != w1.color);
This returns collection of boolean values for one by one comparison of colors. You can use Any(b => !b) to check if there is any non equal color.
Keep in mind, that both windows lists should have same length (only corresponding elements will produce result). So, you can start from checking length of lists before doing zip. If items count is different, then lists are not same.
In order to compare windows you should override Equals and GetHashCode methods:
public class Window
{
public string Size { get; set; }
public string Color { get; set; }
public bool IsEnergySaving { get; set; }
public Window() { }
public Window(string size, string color, bool isEnergySaving)
{
Size = size;
Color = color;
IsEnergySaving = isEnergySaving;
}
public override bool Equals(object obj)
{
Window other = obj as Window;
if (other == null)
return false;
return Color == other.Color &&
IsEnergySaving == other.IsEnergySaving;
}
public override int GetHashCode()
{
int hash = 19;
hash = hash * 23 + Color.GetHashCode();
hash = hash * 23 + IsEnergySaving.GetHashCode();
return hash;
}
}
Here is house class slightly improved:
public class House
{
public House(string number)
{
Number = number;
Windows = new List<Window>();
}
public string Number { get; private set; }
public List<Window> Windows { get; private set; }
public House WithWindow(string size, string color, bool energySaving = false)
{
Windows.Add(new Window(size, color, energySaving));
return this;
}
}
With this fluent API you can create houses like this:
House h1 = new House("1")
.WithWindow("1", "blue", true)
.WithWindow("1", "black")
.WithWindow("1", "red");
House h2 = new House("1")
.WithWindow("2", "blue")
.WithWindow("2", "black");
And finding changed and new windows will look like:
var changedAndNewWindows = h2.Windows.Except(h1.Windows);

You can use Parallel.For in this context since you are comparing two lists element by element and without editing (if you need to edit you have to use lock):
var count = Math.Min(h1.Windows.Count, h2.Windows.Count);
Parallel.For(0, count, (index)=>{
//Do your operations here
if(h1.Windows[index].Color == h2.Windows[index].Color)
{
}
});

How do I Find an object up the list I am iterating through

I am iterating through a List of objects of Type "prvEmployeeIncident".
The object has the following properties:
public DateTime DateOfIncident { get; set; }
public bool IsCountedAsAPoint;
public decimal OriginalPointValue;
public bool IsFirstInCollection { get; set; }
public bool IsLastInCollection { get; set; }
public int PositionInCollection { get; set; }
public int DaysUntilNextPoint { get; set; }
public DateTime DateDroppedBySystem { get; set; }
public bool IsGoodBehaviorObject { get; set; }
My List is sorted by the DateOfIncident property. I would like to find the next object up the list where IsCounted == true and change it to IsCounted = false.
One question:
1) How do I find this object up the list ?

If I understand your question correctly, you can use LINQ FirstOrDefault:
var nextObject = list.FirstOrDefault(x => x.IsCountedAsAPoint);
if (nextObject != null)
nextObject.IsCountedAsAPoint = false;

If I understand correctly this can be solved with a simple foreach loop. I don't exactly understand your emphasis on "up" as you don't really move up a list, you traverse it. Anyways, the following code snippet finds the first Incident where IsCounted is true and changes it to false. If you're starting from a given position change the for each loop to a for loop and start at i = currentIndex with the exit condition being i < MyList.Count. Leave the break statement to ensure you only modify one Incident object.
foreach (prvEmployeeIncident inc in MyList)
{
if (inc.IsCountedAsAPoint)
{
inc.IsCountedAsAPoint = false;
break;
}
}

You can use List(T).FindIndex to search up the list.
Example:
public class Foo
{
public Foo() { }
public Foo(int item)
{
Item = item;
}
public int Item { get; set; }
}
var foos = new List<Foo>
{
new Foo(1),
new Foo(2),
new Foo(3),
new Foo(4),
new Foo(5),
new Foo(6)
};
foreach (var foo in foos)
{
if(foo.Item == 3)
{
var startIndex = foos.IndexOf(foo) + 1;
var matchedFooIndex = foos.FindIndex(startIndex, f => f.Item % 3 == 0);
if(matchedFooIndex >= startIndex) // Make sure we found a match
foos[matchedFooIndex].Item = 10;
}
}
Just be sure you do not modify the list itself since that will throw an exception.