what type does my object query return?

Question

Public Function List_category() As Myobj 
Dim query = From subcat In _dataContext.subcategories, _ 
cat In _dataContext.categories _ 
Where subcat.CategoryID = cat.CategoryID _
                Select New Myobj() With { _
                .SubcatId = subcat.SubCategoryID, _
                .SubcatName = subcat.SubCategoryName, _
                .CatId = cat.CategoryID, _
                .CatName = cat.CategoryName _
                }
return ?????????
End Function

Public Class Myobj

Private m_SubcatId As Integer
Private m_SubcatName As String
Private m_catId As Integer
Private m_catName As String

Public Property SubcatId() As Integer
    Get
        Return m_SubcatId
    End Get
    Private Set(ByVal value As Integer)
        m_SubcatId = value
    End Set
End Property

Public Property SubcatName() As String
    Get
        Return m_SubcatName
    End Get
    Private Set(ByVal value As String)
        m_SubcatName = value
    End Set
End Property

Public Property CatId() As Integer
    Get
        Return m_catId
    End Get
    Private Set(ByVal value As Integer)
        m_catId = value
    End Set
End Property

Public Property CatName() As String
    Get
        Return m_catName
    End Get
    Private Set(ByVal value As String)
        m_catName = value
    End Set
End Property

End Class

doesnt works!!!!

It Says 'Set' accessor of property 'SubcatName' is not accessible.

Answer 1

You can create a custom type and modify your select to instantiate that for the return. Take a look here: http://stackoverflow.com/questions/460831/linq-to-sql-return-from-function-as-iqueryablet

Answer 2

Compiler is just telling you that you have declared Private Set on SubcatName and yet ypou are trying to assing a value to it after New Myobj().

For a first run you can declare a POD class (plain old data - just public data, no methods or properties) and once you see it runnung you can go tweaking it, adding methods etc.

If it's really important that all properties are read-only you'll need to try making your querying method a static member of the same class.

Also, there is a way to return anonymous type and cast it back to equivalent anonymous type declared at the receiving side. Got to move on to C# though :-)

Example (read article):

// Method that returns anonymous type as object
object ReturnAnonymous()
{
  return new { City="Prague", Name="Tomas" };
}

// Application entry-point
void Main()
{
  // Get instance of anonymous type with 'City' and 'Name' properties
  object o = ReturnAnonymous();

  // This call to 'Cast' method converts first parameter (object) to the
  // same type as the type of second parameter - which is in this case 
  // anonymous type with 'City' and 'Name' properties
  var typed = Cast(o, new { City="", Name="" });
  Console.WriteLine("Name={0}, City={1}", typed.Name, typed.City);
}

// Cast method - thanks to type inference when calling methods it 
// is possible to cast object to type without knowing the type name
T Cast<T>(object obj, T type)
{
  return (T)obj;
}