Working with ADO.NET Datasets and .NET Objects using Crystal Reports and ASP.NET 2.0 - .NET objects as data sources to Crystal Reports: adding a collection class

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In previous section, we added a class which holds only one row of information from the "Orders" table (but with few fields).  Now, we are adding one more class to hold a set of rows from the "Orders" table based on the "Order" entity class.  This class must be named "Orders.vb" and must inherit from the "CollectionBase" class (part of the .NET Framework Class Library).

Add a new class named "Orders.vb" and copy the following code:

Imports Microsoft.VisualBasic

 

Public Class Orders

  Inherits CollectionBase

 

  Public Sub add(ByVal e As Order)

    List.Add(e)

  End Sub

 

  Public Sub delete(ByVal e As Order)

    List.Remove(e)

  End Sub

 

  Public Sub delete(ByVal index As Integer)

    If index < 0 Or index > List.Count - 1 Then

      Throw New Exception("Invalid index to remove")

    End If

    List.RemoveAt(index)

  End Sub

 

  Default Public Overridable ReadOnly Property Item(ByVal index As Integer) As Order

    Get

      Return CType(Me.List(index), Order)

    End Get

  End Property

 

End Class

It is basically a collection class which holds a group of objects related to the "Order" class.

Next: .NET objects as data sources to Crystal Reports: adding and binding a crystal report >>
 

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