DataRow.BeginEdit Method ()

 

Starts an edit operation on a DataRow object.

Namespace:   System.Data
Assembly:  System.Data (in System.Data.dll)

Public Sub BeginEdit

Exception Condition
InRowChangingEventException

The method was called inside the RowChanging event.

DeletedRowInaccessibleException

The method was called upon a deleted row.

Use the BeginEdit method to put a DataRow into edit mode. In this mode, events are temporarily suspended, letting the user make changes to more than one row without triggering validation rules. For example, if you must make sure that the value of the column for a total amount is equal to the values for the debit and credit columns in a row, you can put each row into edit mode to suspend the validation of the row values until the user tries to commit the values.

The BeginEdit method is called implicitly when the user changes the value of a data-bound control; the EndEdit method is called implicitly when you invoke the AcceptChanges method for the DataTable object. While in this edit mode, the DataRow stores representations of the original and new proposed values. Therefore, as long as the EndEdit method has not been called, you can retrieve either the original or proposed version by passing either DataRowVersion.Original or DataRowVersion.Proposed for the version parameter of the Item property. You can also cancel any edits at this point by invoking the CancelEdit method.

To see if the row contains an original or proposed value, call the HasVersion method.

System_CAPS_noteNote

The BeginEdit method temporarily suspends RowChanging events, but the delete operation does not.

The example creates a simple DataTable with one DataColumn and five DataRow objects, and a UniqueConstraint. A RowChanged event handler is also added to monitor when the row's value is changing. After invoking BeginEdit on the existing rows, the constraint and event are temporarily disabled and the original and proposed values are printed. The BeginEdit is again invoked to set two rows to the same value. When EndEdit is called, the UniqueConstraint is enforced on the identical values.

Private Sub DemonstrateRowBeginEdit()
    Dim table As New DataTable("table1")
    Dim column As New DataColumn("col1", Type.GetType("System.Int32"))
    AddHandler table.RowChanged, AddressOf Row_Changed
    table.Columns.Add(column)

    ' Add a UniqueConstraint to the table.
    table.Constraints.Add(New UniqueConstraint(column))

    ' Add five rows.
    Dim newRow As DataRow

    Dim i As Integer
    For i = 0 To 4
        ' RowChanged event will occur for every addition.
        newRow = table.NewRow()
        newRow(0) = i
        table.Rows.Add(newRow)
    Next i

    ' AcceptChanges.
    table.AcceptChanges()

    ' Invoke BeginEdit on each.
    Console.WriteLine(ControlChars.Cr _
       & " Begin Edit and print original and proposed values " _
       & ControlChars.Cr)
    Dim row As DataRow
    For Each row In  table.Rows           
        row.BeginEdit()
        row(0) = CInt(row(0)) & 10
        Console.Write(ControlChars.Tab & " Original " & ControlChars.Tab _
           & row(0, DataRowVersion.Original).ToString())
        Console.Write(ControlChars.Tab & " Proposed " & ControlChars.Tab _
           & row(0, DataRowVersion.Proposed).ToString() & ControlChars.Cr)
    Next row
    Console.WriteLine(ControlChars.Cr)

    ' Accept changes
    table.AcceptChanges()

    ' Change two rows to identical values after invoking BeginEdit.
    table.Rows(0).BeginEdit()
    table.Rows(1).BeginEdit()
    table.Rows(0)(0) = 100
    table.Rows(1)(0) = 100
    Try
        ' Now invoke EndEdit. This will cause the UniqueConstraint
        ' to be enforced.
        table.Rows(0).EndEdit()
        table.Rows(1).EndEdit()
    Catch e As Exception
 ' Process exception and return.
        Console.WriteLine("Exception of type {0} occurred.", _
           e.GetType().ToString())
    End Try
End Sub

Private Sub Row_Changed _
(sender As Object, e As System.Data.DataRowChangeEventArgs)
    Dim table As DataTable = CType(sender, DataTable)
    Console.WriteLine("RowChanged " & e.Action.ToString() _
       & ControlChars.Tab & e.Row.ItemArray(0).ToString())
End Sub

.NET Framework
Available since 1.1
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