Question

I have an existing controller action as below.

Public Function List(ByVal UserID As Integer, Optional ByVa; Filter As String = Nothing) As ActionResult
    Dim records

    If Filter IsNot Nothing Then
        records = context.Contacts.Where(Function(x) x.UserID = UserID and x.Name.Contains(Filter))
    Else
        records = context.Contacts.Where(Function(x) x.UserID = UserID)
    End If

    return View(records)
End Function

I desire to make it simpler as below.

Public Function List(ByVal UserID As Integer, Optional ByVa; Filter As String = Nothing) As ActionResult
    Dim records = context.Contacts.Where(Function(x) x.UserID = UserID)

    If Filter IsNot Nothing Then
        records = records.Where(Function(x) x.Name.Contains(Filter))
    End If

    return View(records)
End Function

Will EF fire two queries if Filter is passed or is it intelligent enough to fire just one query?

Answer 1

Yes, one query – this is the nature of the IQueryable interface. All methods which return an IQueryable should not execute anything until the IQueryable’s enumerator is accessed.