StrataFrame Forum » StrataFrame Application Framework - V1 » WebForms (How do I?) » Deleting the first item in a List

Deleting the first item in a List

Charles Thomas Blankenship — Fri, 08 Dec 2006 09:00:50 GMT

Everytime I delete the first item in my list I get the following error:

The CurrentRow could not be evaluated because the CurrentRowIndex is out of range. Business object record count: 7. CurrentRowIndex: -1.

A closer evaluation of the code shows the following issue ... when the list is at the first item ... the _CurrentRowIndex is already at 0 ... the -= 1 changes this to a negative one which throws the error above. Should I put a check in there to see if the _CurrentrowIndex is already 0 before decrementing?



                If loCurrentPk.Equals(PKValue) Then

                    '-- Remove the current row and navigate to the next row

                    loRow = Me.CurrentRow

                    loRow.Delete()

                    loRow.AcceptChanges()



                    '-- Decrement the index and navigate

                    Me._CurrentRowIndex -= 1

                    Me.Navigate(BusinessNavigationDirection.Next)

                Else

                    '-- Find the row to delete

                    If Me.SeekToPrimaryKey(PKValue) Then

                        '-- Remove the row

                        loRow = Me.CurrentRow

                        loRow.Delete()

                        loRow.AcceptChanges()



                        '-- Move back to the original row

                        Me.SeekToPrimaryKey(loCurrentPk)

                    End If

                End If

This has been a long hard non-billable day my friends.

Thanks,

CTBlankenship

RE: Deleting the first item in a List

Trent L. Taylor — Fri, 08 Dec 2006 09:00:50 GMT

No problem :)

RE: Deleting the first item in a List

Charles Thomas Blankenship — Fri, 08 Dec 2006 08:26:25 GMT

Ah ... those two pieces of information are nice to know. Thanks for your time and attention my friend.

RE: Deleting the first item in a List

Trent L. Taylor — Thu, 07 Dec 2006 21:50:47 GMT

After looking at the code and running a test, the code in the DeleteByPrimaryKey is actually correct. The Navigate accounts for a negative row index. There is something else going on in your environment that could be causing the problem. Just so you know, you don't even need any records in the BO in order to delete a record from the server. If you are wanting to delete a record from the server that is already in your BO, the use the DeleteCurrentRow method...you will have fewer issues with other bindings and delegates that may be in the formula.

RE: Deleting the first item in a List

Trent L. Taylor — Thu, 07 Dec 2006 21:44:46 GMT

Oh....I will look into this....you will get the results you are looking for calling the following method:

[codesnippet]MyBO.DeleteCurrentRow(False)[/codesnippet]

But be sure to navigate to the proper row before smoking it:

[codesnippet]If MyBO.SeekToPrimaryKey(MyPrimaryKey) Then
MyBO.DeleteCurrentRow(False)
End If[/codesnippet]

RE: Deleting the first item in a List

Charles Thomas Blankenship — Thu, 07 Dec 2006 21:39:51 GMT

Hey Buddy:

I'm calling this method ...

Private Function DeleteByPrimaryKey(ByVal PKValue As PrimaryKeyValue) As Integer

which has this code in it



If loCurrentPk.Equals(PKValue) Then

                    '-- Remove the current row and navigate to the next row

                    loRow = Me.CurrentRow

                    loRow.Delete()

                    loRow.AcceptChanges()



                    '-- Decrement the index and navigate

                    Me._CurrentRowIndex -= 1

                    Me.Navigate(BusinessNavigationDirection.Next)

                Else

Notice that the value in Me._CurrentRowIndex is not tested for 0 before a decrement occurs ... in my case this causes the the _CurrentRowIndex to contain a -1 which throws the aforementioned error. Sorry I mislead you by not posting the whole piece of the pie.

Thanks,

CT

RE: Deleting the first item in a List

Trent L. Taylor — Thu, 07 Dec 2006 19:27:08 GMT

You are not going to want to delete through the CurrentRow...this may potentitally wreak havoc on a number of different levels. First of all you should really use the following command:

[codesnippet]MyBO.DeleteCurrentRow(True)[/codesnippet]

The above command will only mark the row as deleted (the True) and not go back to the server, obviously False will go back to the server. Second, if you don't want to commit the changes, then you can call the following command:

[codesnippet]MyBO.CurrentDataTable.AcceptChanges()[/codesnippet]

This wasy you are staying within the logic of the BO. Even if you want to call the delete on the data table directly would be safer than passing of the row reference and the smoking it:

[codesnippet]MyBO.CurrentDataTable.Rows(MyBO.CurrentRowIndex).Delete()[/codesnippet]

Any of these are going to be much safer. I recommend the first option as it remains within the BO logic.