Detect if an object is a ValueTuple

Question

I have a use case where I need to check if a value is a C# 7 ValueTuple, and if so, loop through each of the items. I tried checking with obj is ValueTuple and obj is (object, object) but both of those return false. I found that I could use obj.GetType().Name and check if it starts with "ValueTuple" but that seems lame to me. Any alternatives would be welcomed.

I also have the issue of getting each item. I attempted to get Item1 with the solution found here: How do I check if a property exists on a dynamic anonymous type in c#? but ((dynamic)obj).GetType().GetProperty("Item1") returns null. My hope was that I could then do a while to get each item. But this does not work. How can I get each item?

Update - more code

if (item is ValueTuple) //this does not work, but I can do a GetType and check the name
{
    object tupleValue;
    int nth = 1;
    while ((tupleValue = ((dynamic)item).GetType().GetProperty($"Item{nth}")) != null && //this does not work
        nth <= 8)      
    {
        nth++;
        //Do stuff
    }
}

Answer 1

This is my solution to the problem. A PCL compatible extension class. Special thanks to @dasblinkenlight and @Evk for helping me out!

public static class TupleExtensions
{
    private static readonly HashSet<Type> ValueTupleTypes = new HashSet<Type>(new Type[]
    {
        typeof(ValueTuple<>),
        typeof(ValueTuple<,>),
        typeof(ValueTuple<,,>),
        typeof(ValueTuple<,,,>),
        typeof(ValueTuple<,,,,>),
        typeof(ValueTuple<,,,,,>),
        typeof(ValueTuple<,,,,,,>),
        typeof(ValueTuple<,,,,,,,>)
    });

    public static bool IsValueTuple(this object obj) => IsValueTupleType(obj.GetType());
    public static bool IsValueTupleType(this Type type)
    {
        return type.GetTypeInfo().IsGenericType && ValueTupleTypes.Contains(type.GetGenericTypeDefinition());
    }

    public static List<object> GetValueTupleItemObjects(this object tuple) => GetValueTupleItemFields(tuple.GetType()).Select(f => f.GetValue(tuple)).ToList();
    public static List<Type> GetValueTupleItemTypes(this Type tupleType) => GetValueTupleItemFields(tupleType).Select(f => f.FieldType).ToList();    
    public static List<FieldInfo> GetValueTupleItemFields(this Type tupleType)
    {
        var items = new List<FieldInfo>();

        FieldInfo field;
        int nth = 1;
        while ((field = tupleType.GetRuntimeField($"Item{nth}")) != null)
        {
            nth++;
            items.Add(field);
        }

        return items;
    }
}