VB.NET - GetChanges (and original values) from DataSet

If you use a DataSet on a DataGridView for table maintenance and edits have been made, you may want to be able to see what the original values were compared to the newly entered ones.  You may want to do this to keep record of what values were before the user saves the changes to the database.

My example does one row at a time.  This is good if you do row validation with the RowValidating event.  Assume my code fires off in the RowValidating event. (m_ds is my DataSet that is attached to my grid)

*This is inside of the Row Validating event {

If m_ds.HasChanges then

         GetUserChanges()

End if

}

    ''' <summary>

    '''This code will go through and get all original values from the row and/or the new ones depending on what time of RowState the

    ''' row is in.  These values are retrieved before changes are committed to the dataset with the m_ds.update statement

    ''' </summary>

    ''' <remarks>jefz</remarks>

    Private Sub GetUserChanges()

        Dim dtChanges As New DataTable

        Dim dtRow As DataRow

        Dim strOriginalValue As String = ""

        Dim strNewValue As String = ""

        Dim strType As String = ""

        Try

            'check to see what kind of changes were made to the DataSet: Modified, Added, or Deleted

            If m_ds.HasChanges(DataRowState.Modified) Then

                dtChanges = m_ds.Tables.Item(0).GetChanges(DataRowState.Modified)

                strType = "M"

            ElseIf m_ds.HasChanges(DataRowState.Added) Then

                dtChanges = m_ds.Tables.Item(0).GetChanges(DataRowState.Added)

                strType = "A"

            ElseIf m_ds.HasChanges(DataRowState.Deleted) Then

                dtChanges = m_ds.Tables.Item(0).GetChanges(DataRowState.Deleted)

                strType = "D"

            Else

                Throw New Exception("No changes were found ... Should not be trying to save")

            End If

            dtRow = dtChanges.Rows(0)

            Select Case strType

                'if the row was modified then get the original value as well as the new value from the dataset

                Case "M"

                    For Each Column As DataColumn In dtChanges.Columns

                        strOriginalValue = dtRow(Column, DataRowVersion.Original).ToString

                        strNewValue = dtRow(Column, DataRowVersion.Current).ToString

                    Next

                    'if the row was added then you can only get the new values

                Case "A"

                    For Each Column As DataColumn In dtChanges.Columns

                        strNewValue = dtRow(Column, DataRowVersion.Current).ToString

                    Next

                    'if is going to be deleted then you can only get the old rows

                Case "D"

                    For Each Column As DataColumn In dtChanges.Columns

                        strOriginalValue = dtRow(Column, DataRowVersion.Original).ToString

                    Next

                Case Else

                    Throw New Exception("No changes were found ... Should not be trying to save")

            End Select

        Catch ex As Exception

            Throw ex

        End Try

    End Sub

You can do whatever you want with the values within the select case or if you want to store these values for later use, instead of storing their values into a string variable, you can add them to an array or collection.