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Subject:
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Datagrid update error
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Posted By:
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eresina
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Post Date:
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10/21/2004 11:00:13 AM
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Hello, I have a webform with a datagrid and I receive the following error when doing the update command in the datagrid after editing it:
"Cannot update identity column 'Id_FHora_Horas'"
Here is the code for the datagrid update command:
Private Sub dgeditponto_UpdateCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles dgeditponto.UpdateCommand
'colcoar o valor da ddl no campo da fk
CType(e.Item.Cells(5).Controls(0), TextBox).Text = _
CType(e.Item.FindControl("ddlE_S2"), DropDownList).SelectedItem.Value()
'encher o dataset
FHorasDataAdapter2.Fill(DataSetE_S1)
TipoMovDataAdapter3.Fill(DataSetE_S1)
'identificaar a linha a editar
Dim objEditRow As DataRow = DataSetE_S1.Tables(0).Rows.Find(CType(e.Item.Cells(5).Controls(0), TextBox).Text)
'andar através das celulas da datagrid e colocar a informação no dataset
Dim intCount As Integer
For intCount = 0 To e.Item.Cells.Count - 3
If e.Item.Cells(intCount).Controls.Count > 0 Then
If TypeOf (e.Item.Cells(intCount).Controls(0)) Is TextBox Then
'se é uma etxtbox com dados...
Dim strValue As String = CType(e.Item.Cells(intCount).Controls(0), TextBox).Text
'colocar o valor (or ou o nulo...) no campo respectivo do dataset
If strValue = "" Then
objEditRow.Item(dgeditponto.Columns(intCount).SortExpression) = System.DBNull.Value
Else
If intCount <> 2 Then
objEditRow.Item(dgeditponto.Columns(intCount).SortExpression) = strValue
End If
End If
End If
End If
Next
''uptade backend data
FHorasDataAdapter2.Update(DataSetE_S1, "fhoras_horas")
'deselecciona items da datagrid e faz o rebind
With dgeditponto
.SelectedIndex = -1
.EditItemIndex = -1
.DataSource = DataSetE_S1
.DataBind()
End With
End Sub
Any suggestions? 
Thanks,
Elisa Resina
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Reply By:
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bmains
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Reply Date:
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10/21/2004 12:14:07 PM
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Is your ID field the first field? Try changing your looping to start from the 1 position. You can't change the identity field once it is set.
Brian
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Reply By:
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eresina
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Reply Date:
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10/22/2004 3:24:26 AM
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yes, is the first field in table "Fhoras_Horas" . I don't show it in my datagrid. I changed the counter and I received the same message. I don't have any idea how I can solved it because I don't see any reason for the code not work. In this situation how would you write it?
Thanks again,
Elisa
Elisa Resina
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Reply By:
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bmains
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Reply Date:
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10/22/2004 7:15:40 AM
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Hello,
I usually make the ID field bound, readonly, and hidden and in the first position. You access it with the index of zero. The others can be bound fields, or template columns. Bound fields are accessed by e.item.cells(<index>).text, whereas controls are accessed the way you did it; using findcontrols or the controls collection. I would go for a more manual approach:
With e.Item
Dim intID As Integer = Ctype(.Cells(0).Text, Integer)
Dim strField1 As String = .Cells(1).Text
Dim strField2 As String = .Cells(2).Text
Dim objEditRow As DataRow = DataSetE_S1.Tables(0).Rows.Find(intID)
objEditRow.BeginEdit()
objEditRow("Field1") = strfield1
if (strField2 <> string.Empty) Then
objEditRow("Field2") = strField2
else
objEditRow("Field2") = DbNull.Value
end if
objEditRow.EndEdit()
FHorasDataAdapter2.Update(DataSetE_S1, "fhoras_horas")
End With
Brian
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