In C# how can i check if T is of type IInterface and cast to that if my object supports that interface?

Question

In C#, I have a function that passes in T using generics and I want to run a check to see if T is an object that implements a

Answer 1

public IEnumerable<TResult> FilterMe<TResult>(IEnumerable<TResult> linked) where TResult : IFilterable
{
    var dict = GetDict();
    return linked.Where(r => dict.ContainsKey(r.Id));
}

Try replacing FilterMe with this version:

public IEnumerable<T> FilterMe(IEnumerable<IFilterable> linked)
{
    var dict = GetDict();
    return linked.Where(r => dict.ContainsKey(r.Id)).Cast<T>();
}

Then, were you call, change your code to this:

if (typeof(IFilterable).IsAssignableFrom(typeof(T)))
{
    //Filterme is a method that takes in IEnumerable<IFilterable>
    var filterable = entities.Cast<IFilterable>();
    entities = FilterMe(entities).AsQueryable();
}

Answer 2

if (typeof(IMyInterface).IsAssignableFrom(typeof(T))

This checks whether a variable of type IMyInterface can be assigned from an instance of type T.