Determine if object derives from collection type

Question

I want to determine if a generic object type (\"T\") method type parameter is a collection type. I would typically be sending T through as a Generic.List but it could be any co

Answer 1

For simplicity and code sharing, I usually use this extension method:

public static bool IsGenericList(this object obj)
{
    return IsGenericList(obj.GetType());
}

public static bool IsGenericList(this Type type)
{
    if (type == null)
    {
        throw new ArgumentNullException("type");
    }

    foreach (Type @interface in type.GetInterfaces())
    {
        if (@interface.IsGenericType)
        {
            if (@interface.GetGenericTypeDefinition() == typeof(ICollection<>))
            {
                // if needed, you can also return the type used as generic argument
                return true;
            }
        }
    }

    return (type.GetInterface("IEnumerable") != null);
}