Question

I have a IEnumerable<Person> for example.

I want to be able to make it List<Person> at runtime

I have the below code but errors saying I can’t convert System Runtime type

Is there something I’m missing?

private static readonly MethodInfo enumerableToListMethod = typeof(Enumerable).GetMethod("ToList", BindingFlags.Public | BindingFlags.Static);

//genericType will be Person
var genericType = modelType.GetGenericArguments().First();

var genericToListMethod = enumerableToListMethod.MakeGenericMethod(new[] { genericType });

//modelType is IEnumerable<Person>
var ienumtype = genericToListMethod.Invoke(null, new object[] { modelType });

Activator.CreateInstance(ienumtype.GetType());

Answer 1

You’ve gotta pass in the IEnumerable to the invoke, NOT the type of the enumerable – also, calling invoke will return the List, not a Type.

put in code:

var instance = < the IEnumerable >;
var modelType = instance.GetType();

//modelType is IEnumerable<Person>
var enumerableAsList = genericToListMethod.Invoke(null, new object[] { instance});

Based on your comments, I’m guessing you’re after something more like this:

Func<IEnumerable<T>, List<T>> MakeMeAToListerForEnumerablesOfType<T>()
{
    var itemType = typeof(T);
    var enumerableToListMethod = typeof(Enumerable).GetMethod("ToList", BindingFlags.Public | BindingFlags.Static);
    var genericToListMethod = enumerableToListMethod.MakeGenericMethod(new[] { itemType });
    return (Func<IEnumerable<T>, List<T>>)Delegate.CreateDelegate(typeof(Func<IEnumerable<T>, List<T>>), genericToListMethod);
}

Which you would call like:

IEnumerable<string> enumerable = new string[] { "a", "b", "c" };
var toLister = MakeMeAToListerForEnumerablesOfType<string>();

Derp. Missed the call…

var enumerableAsList = toLister(enumerable);