CODEWITHSUNDEEP
c#reflectioncollections
Ondra Starenko
Ondra Starenko

Reputation: 596

How to know if a property is a type of List<MyClass>?

I have this in these classes.

public class MyClass:BaseClass
{ }

public class BaseClass
{ }

public class CollectionClass
{
   public string SomeProperty {get; set;}

   public List<MyClass> Collection {get; set;}
}

In my code I want to find out if the property in some object (e. g. CollectionClass) is a type of List<BaseClass> also I want to return true if the property is a type of List<MyClass>. The code below explains that.

public bool ContainsMyCollection(object obj)
{
   foreach(var property in obj.GetType().GetProperties())
   {
      //  Idk how to accomplish that
      if(property isTypeof List<BaseClass>)
         return true;
   }
   return false
}

Upvotes: 1

Views: 97

Answers (1)

ProgrammingLlama
ProgrammingLlama

Reputation: 38727

You need to check if you have a closed type of List<>. This can be done like so:

if(property.PropertyType.IsGenericType
    && property.PropertyType.GetGenericTypeDefinition() == typeof(List<>))

and then you have to check if the generic argument (the T part of List<T>) is assignable to your base type:

if (typeof(BaseClass).IsAssignableFrom(property.PropertyType.GetGenericArguments()[0]))

Putting that together, you get this:

public bool ContainsMyCollection(object obj)
{
   foreach(var property in obj.GetType().GetProperties())
   {
      //  Idk how to accomplish that
      if(property.PropertyType.IsGenericType 
         && property.PropertyType.GetGenericTypeDefinition() == typeof(List<>)
         && typeof(BaseClass).IsAssignableFrom(property.PropertyType.GetGenericArguments()[0]))
      {
          return true;
      }
   }
   return false;
}

Note that, as explained in the comments, List<MyClass> isn't derived from List<BaseClass>, even if MyClass is derived from BaseClass. So, for example, List<BaseClass> a = new List<MyClass>(); will fail. That falls outside the scope of your question, but I figured I'd give you the heads up in case you didn't already know.

Upvotes: 2

Related Questions