CODEWITHSUNDEEP
c#generics
user3466681
user3466681

Reputation: 49

How to access property value in generic method in C#?

Imagine I have several classes of different types with the same property.

I want to make a generic method that should acess the value of the property of those classes.

The following code is invalid and will throw this error :

Cannot resolve method 'GetValue(T)' (...)

.. so what's the proper way to do this? 

public static List<int> FooBar<T>(T myObject)
{
  var myValue = typeof(T).GetProperty("myList").GetValue(myObject);

  return myValue;
}

Upvotes: 1

Views: 84

Answers (3)

Derviş Kayımbaşıoğlu
Derviş Kayımbaşıoğlu

Reputation: 30545

If you really want to do this with generics, try the code below

 return (List<int>)(typeof(T).GetProperty("myList").GetValue(myObject, null))

Upvotes: 1

Hien Nguyen
Hien Nguyen

Reputation: 18975

you can do like this myObject.GetType().GetProperty("myList").GetValue(myObject, null);

Upvotes: 1

Marc Gravell
Marc Gravell

Reputation: 1062550

The "proper" way to do this is probably to have a where T : SomeInterfaceOrBaseType, i.e. the thing that has a myList member - and then just access it; i.e. return myObject.myList;

interface IFoo {
    List<int> myList {get;}
}
public static List<int> FooBar<T>(T myObject) where T : IFoo {
    return myObject.myList;
}

But... by the time you've done that, there's not really a need for the method any more, as if the caller knows that the type is an IFoo, they can do that themselves.

If you must do it via reflection... well, that's hard. It might be easier to just abuse dynamic:

public static List<int> FooBar<T>(T myObject)
{
    dynamic obj = myObject;
    List<int> myList = obj.myList;
    return myList;
}

Upvotes: 3

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