Question

I want to port some of my EntityFramework C# code into VB.NET. I’m trying different online code convertor but they can’t solve this problem for me.

I have these two functions.

public List<T> Find<T>(Func<T, bool> predicate) where T : class
    {
        var objectSet = db.CreateObjectSet<T>();
        return objectSet.Where<T>(predicate).ToList();
    }

    public void Delete<T>(Func<T, bool> predicate) where T : class
    {
        var objectSet = db.CreateObjectSet<T>();
        IEnumerable<T> records = from x in objectSet.Where<T>(predicate) select x;

        foreach (T record in records)
        {
            objectSet.DeleteObject(record);
        }
    }

Now convertors tell me this:

Public Function Find(Of T As Class)(predicate As Func(Of T, Boolean)) As List(Of T)
    Dim objectSet = db.CreateObjectSet(Of T)()
    Return objectSet.Where(Of T)(predicate).ToList()
End Function

Public Sub Delete(Of T As Class)(predicate As Func(Of T, Boolean))
    Dim objectSet = db.CreateObjectSet(Of T)()
    Dim records As IEnumerable(Of T) = From x In objectSet.Where(Of T)(predicate) Select x

    For Each record As T In records
        objectSet.DeleteObject(record)
    Next
End Sub

But I get two errors, both for objectSet.Where<T>(predicate) which is:

Overload resolution failed because no accessible ‘Where’ accepts this number of type arguments.

Answer 1

Simply remove the type argument from your call to Where, it’s unnecessary anyway. Secondly, decide on a style: either use LINQ or functions, not both.

That is,

• either write:

  Dim records As IEnumerable(Of T) = From x In objectSet Where predicate(x) Select x
  

  … but in VB you can leave off the Select x:

  Dim records As IEnumerable(Of T) = From x In objectSet Where predicate(x)
  

• or write:

  Dim records As IEnumerable(Of T) = objectSet.Where(predicate)
  

Same for Find. Simply write:

Return objectSet.Where(predicate).ToList()