How do I check if a given value is a generic list?

Question

public bool IsList(object value)
    {
        Type type = value.GetType();
        // Check if type is a generic list of any type
    }

What's the best way to check if the given object is a list, or can be cast to a list?

Answer 1

Probably the best way would be to do something like this:

IList list = value as IList;

if (list != null)
{
    // use list in here
}

This will give you maximum flexibility and also allow you to work with many different types that implement the IList interface.

Answer 2

if(value is IList && value.GetType().GetGenericArguments().Length > 0)
{

}

Answer 3

Maybe you find answer here http://stackoverflow.com/questions/755200/how-do-i-detect-that-an-object-is-a-generic-collection-and-what-types-it-contain

Answer 4

if(value is IList && value.GetType().IsGenericType) {

}

Answer 5

 bool isList = o.GetType().IsGenericType 
                && o.GetType().GetGenericTypeDefinition() == typeof(IList<>));

Answer 6

public bool IsList(object value) {
    return value is IList 
        || IsGenericList(value);
}

public bool IsGenericList(object value) {
    var type = value.GetType();
    return type.IsGenericType
        && typeof(List<>) == type.GetGenericTypeDefinition();
}

Answer 7

For you guys that enjoy the use of extension methods:

public static bool IsGenericList(this object o)
{
    bool isGenericList = false;

    var oType = o.GetType();

    if (oType.IsGenericType && (oType.GetGenericTypeDefinition() == typeof(List<>)))
     isGenericList = true;

    return isGenericList;
}

So, we could do:

if(o.IsGenericList())
{
 //...
}