Help with This Line of Code: from VB to C#. PLEASE

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I am re-writing a sample application from VB.net to C#, its a sample tutorial about using DataSets in n-tier applications. I succeded in all but this line of code:

C#

Dim changes = CType(Me.OrdersDataSet.GetChanges, NorthwindEntities.OrdersDataSet)

My understanding of CType as used in VB is to cast one object to another. How do i cast this in C#?

The complete code for the Sub is:

VB

Private Sub OrdersBindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OrdersBindingNavigatorSaveItem.Click
        Me.Validate()
        Me.OrdersBindingSource.EndEdit()

        Using proxy As New NorthwindService.ServiceClient
            Dim changes = CType(Me.OrdersDataSet.GetChanges, NorthwindEntities.OrdersDataSet)

            If changes IsNot Nothing Then
                If proxy.SaveOrders(changes) Then

                    Dim addedrows = From row In Me.OrdersDataSet.Orders _
                                    Where row.RowState = DataRowState.Added

                    For Each row In addedrows.ToArray
                        row.Delete()
                    Next

                    Me.OrdersDataSet.Merge(changes)
                    Me.OrdersDataSet.AcceptChanges()

                    MsgBox("saved")
                Else
                    MsgBox("Not saved")
                End If
            End If
        End Using
    End Sub

Thank you in advance.

Posted 19-Aug-10 11:07am

coommark

Updated 19-Aug-10 11:09am

v2

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3 solutions

Solution 2

I haven't tested, but you should try this:

NorthwindEntities.OrdersDataSet changes = this.OrdersDataSet.GetChanges() as NorthwindEntities.OrdersDataSet;

This allows you to test for null before entering the next block.

Cheers.

(oops on the Me, should be this)

Posted 19-Aug-10 11:11am

TheyCallMeMrJames

Updated 19-Aug-10 11:12am

v2

Solution 3

Thank you James and Christian. Thank you so very much for the quick response. Your answers were right.

But if you dont mind let me just pose another question. I was actually trying to re-code a tutorial from VB to C# about using DataSets in an n-tier architecture from here: http://windowsclient.net/learn/video.aspx?v=14625[]. Everything works fine, but I have not been able to get Updates, even though I can fetch.

Please will you take a look and help me with what I need to do to make it update?

Thank you. Thank you. Thank everyone here who helps reply when we ask questions. Thank you all.

Waiting and hoping someone will help.

Posted 19-Aug-10 13:19pm

coommark

Comments

Christian Graus 19-Aug-10 19:36pm

You should not push 'answer' to ask a question. You'd be better off asking a new question, which this is. Sorry, I don't have time to work through a tutorial for you.

coommark 19-Aug-10 19:49pm

Hmmm... Christian your answer was really great. Sorry I pushed 'answer' to ask a question. I am just kind of stuck and needed help. Would not do that again as you said. Thank you. I appreciate your help. I really do! Sorry if i asked to much. Thank you for your answers. Thank you.

Toli Cuturicu 20-Aug-10 7:01am

Reason for my vote of 1
fake answer

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Christian Graus · Accepted Answer · 2010-08-19T11:11:00

Solution 1

In C# you cast as in C++ - Bitmap b = (Bitmap)n; Or you can use 'as', Bitmap b = n as Bitmap. the difference is that as will return null if it fails and a failed cast will throw an exception.

C#

NorthwindEntities.OrdersDataSet changes = this.OrdersDataSet.GetChanges() as NorthwindEntities.OrdersDataSet;

would be my guess.

Posted 19-Aug-10 11:11am

Christian Graus

Comments

TheyCallMeMrJames 19-Aug-10 17:12pm

Reason for my vote of 5
doh! beat me by a fraction of a second!

coommark 19-Aug-10 19:48pm

Hmmm... Christian your answer is really great. Sorry I pushed 'answer' to ask a question. I am just kind of stuck and needed help. Would not do that again as you said. Thank you. I appreciate your help. I really do!