CODEWITHSUNDEEP
c#asp.net.netgenericsreflection
SamuraiJack
SamuraiJack

Reputation: 5539

How to find out whether given object is Generic List<T> or List of List <T>?

List<List<HeaderTypeEnq<dynamic>>> IDEnq = new List<List<HeaderTypeEnq<dynamic>>>();
List<HeaderTypeEnq<dynamic>> IDListEnq = new List<HeaderTypeEnq<dynamic>>();

for (int i = 0; i < enq.Id.Count; i++)
{
    IDListEnq.Add(new HeaderTypeEnq<dynamic>() { FieldTag = "ID", FieldName = "Segment Tag", Value = enq.Id[i].SegmentTag, Mandatory = "Y", CharacterType = "A", MaxLength = 03 });
    IDListEnq.Add(new HeaderTypeEnq<dynamic>() { FieldTag = "01", FieldName = "ID Type", Value = enq.Id[i].IDType, Mandatory = "Y", CharacterType = "N", MaxLength = 02 });
    IDListEnq.Add(new HeaderTypeEnq<dynamic>() { FieldTag = "02", FieldName = "ID Number", Value = enq.Id[i].IDNumber, Mandatory = "N", CharacterType = "P", MaxLength = 30 });
    IDEnq.Add(IDListEnq);
}
ValidateValue<List<HeaderTypeEnq<dynamic>>>(IDEnq, concaDel);


private string ValidateValue<T>(object EnqTagList, ValidationDelegate del)
{
    //errorstr = "";

    Type typeParameterType = typeof(T);
    if (typeof(T) == typeof(List<HeaderTypeEnq<dynamic>>))
    {
        //code
    }

As per my understanding if (typeof(T) == typeof(List<HeaderTypeEnq<dynamic>>)) should return false for IDEnq (list of list) but it returns true!

Upvotes: 1

Views: 102

Answers (2)

M.kazem Akhgary
M.kazem Akhgary

Reputation: 19149

As per my understanding if (typeof(T) == typeof(List>)) should return false for IDEnq (list of list) but it returns true!

You are calling the generic type like this

 ValidateValue<List<HeaderTypeEnq<dynamic>>>(IDEnq, concaDel);

Generic type is this List<HeaderTypeEnq<dynamic>>. This has nothing to do with IDEnq since its object. So in when you call method like this, T is exactly type of List<HeaderTypeEnq<dynamic>> and the condition becomes true.

You can make your generic method like this. Now EnqTagList is T. You need to get the type of its elements.

private string ValidateValue<T>(T EnqTagList, ValidationDelegate del) 
{
    if (EnqTagList.GetType().GetGenericArguments()[0] == typeof(List<HeaderTypeEnq<dynamic>>))
    {
     //code
    }
}

Upvotes: 0

poke
poke

Reputation: 387667

In order to check whether a type t is a list of lists, you could do something like this:

if (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(List<>))
{
    Type elementType = t.GetGenericArguments()[0];

    if (elementType.IsGenericType && elementType.GetGenericTypeDefinition() == typeof(List<>))
        Console.WriteLine("t is a list of lists");
    else
        Console.WriteLine("t is just a list");
}
else
    Console.WriteLine("t is not a list");

Upvotes: 1

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