[Resolved] Problem with data-bound controls validation

[mf12]

Doing it manually would probably be better, yes, but that's exactly what I'm avoiding since I have about 50 different fields on that single table so creating them automatically saves a whole lot of work.

This is what I came up with, probably not the best solution, but it works:

Private Sub GenericTextBox_Validating(sender As Object, e As System.ComponentModel.CancelEventArgs)
        If sender.Text.Length = 0 Then
            sender.CausesValidation = False
            Dim currentRow As DataRowView = TryCast(EnsaiosBindingSource.Current, DataRowView)
            currentRow.BeginEdit()
            currentRow(sender.DataBindings.Item("Text").BindingMemberInfo.BindingField) = System.DBNull.Value
            currentRow.EndEdit()
            sender.CausesValidation = True
        End If
    End Sub

Thank you for your help Kevin.

[kareninstructor]

Doing it manually would probably be better, yes, but that's exactly what I'm avoiding since I have about 50 different fields on that single table so creating them automatically saves a whole lot of work.

This is what I came up with, probably not the best solution, but it works:

Private Sub GenericTextBox_Validating(sender As Object, e As System.ComponentModel.CancelEventArgs)
        If sender.Text.Length = 0 Then
            sender.CausesValidation = False
            Dim currentRow As DataRowView = TryCast(EnsaiosBindingSource.Current, DataRowView)
            currentRow.BeginEdit()
            currentRow(sender.DataBindings.Item("Text").BindingMemberInfo.BindingField) = System.DBNull.Value
            currentRow.EndEdit()
            sender.CausesValidation = True
        End If
    End Sub

Thank you for your help Kevin.

Your welcome for the help.
Might I suggest trying to set Option Strict On. Although your code above works it is late binding meaning if there was a possibilty of an issue with the code having Option Strict On gives you a better chance at correcting it prior to running the app.

So for the code above the following would be fine with Option Strict One

Private Sub GenericTextBox_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs)
    Dim CurrentBox = DirectCast(sender, TextBox)

    If CurrentBox.Text.Length = 0 Then
        CurrentBox.CausesValidation = False
        Dim currentRow As DataRowView = TryCast(EnsaiosBindingSource.Current, DataRowView)
        currentRow.BeginEdit()
        currentRow(CurrentBox.DataBindings.Item("Text").BindingMemberInfo.BindingField) = System.DBNull.Value
        currentRow.EndEdit()
        CurrentBox.CausesValidation = True
    End If
End Sub

My original suggestion would then be (for generic usage)

Private Sub GenericDecimalTextBox_TextChanged(ByVal sender As Object, ByVal e As EventArgs)
    Dim CurrentBox = DirectCast(sender, TextBox)

    If CurrentBox.Text.Equals("") Then
        Dim currentRow As DataRowView = TryCast(bsDecimals.Current, DataRowView)
        Dim FieldName As String = CurrentBox.DataBindings.Item("Text") _
                                  .BindingMemberInfo.BindingField

        If chkUseNull.Checked Then
            currentRow.Row(FieldName) = System.DBNull.Value
        Else
            currentRow.Row(FieldName) = 0
        End If
    End If

End Sub

[mf12]

Your welcome for the help.
Might I suggest trying to set Option Strict On. Although your code above works it is late binding meaning if there was a possibilty of an issue with the code having Option Strict On gives you a better chance at correcting it prior to running the app.

So for the code above the following would be fine with Option Strict One

Private Sub GenericTextBox_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs)
    Dim CurrentBox = DirectCast(sender, TextBox)

    If CurrentBox.Text.Length = 0 Then
        CurrentBox.CausesValidation = False
        Dim currentRow As DataRowView = TryCast(EnsaiosBindingSource.Current, DataRowView)
        currentRow.BeginEdit()
        currentRow(CurrentBox.DataBindings.Item("Text").BindingMemberInfo.BindingField) = System.DBNull.Value
        currentRow.EndEdit()
        CurrentBox.CausesValidation = True
    End If
End Sub

My original suggestion would then be (for generic usage)

Private Sub GenericDecimalTextBox_TextChanged(ByVal sender As Object, ByVal e As EventArgs)
    Dim CurrentBox = DirectCast(sender, TextBox)

    If CurrentBox.Text.Equals("") Then
        Dim currentRow As DataRowView = TryCast(bsDecimals.Current, DataRowView)
        Dim FieldName As String = CurrentBox.DataBindings.Item("Text") _
                                  .BindingMemberInfo.BindingField

        If chkUseNull.Checked Then
            currentRow.Row(FieldName) = System.DBNull.Value
        Else
            currentRow.Row(FieldName) = 0
        End If
    End If

End Sub

Thanks lol, that was some code I had just written in a rush.

Today, after doing some more research, I found this:
http://stackoverflow.com/questions/4...921107#4921107
http://msdn.microsoft.com/en-us/libr...ndp1_v3_topic5

This is the most important part of that stackoverflow response:

Once the data source has been updated (to DBNull), the binding mechanism will attempt to then repopulate the Textbox with the newly updated data source value. When the underlying data source value is DBNull, the value used for the bound control is governed by the Binding class's NullValue property.

So, as a TextBox's Text property is a String and it gets assigned a null value, an error occurs.
The solution is to change the BindigClass' NullValue property and set it to a valid value (i.e. String.Empty).

This is quite easy when we manually add the bindings to a few controls in our code but I wonder if there's a way to do the same with controls and bindings created by the form designer...

[kareninstructor]

Thanks lol, that was some code I had just written in a rush.

Today, after doing some more research, I found this:
http://stackoverflow.com/questions/4...921107#4921107
http://msdn.microsoft.com/en-us/libr...ndp1_v3_topic5

This is the most important part of that stackoverflow response:


So, as a TextBox's Text property is a String and it gets assigned a null value, an error occurs.
The solution is to change the BindigClass' NullValue property and set it to a valid value (i.e. String.Empty).

This is quite easy when we manually add the bindings to a few controls in our code but I wonder if there's a way to do the same with controls and bindings created by the form designer...

In regards to working with the form designer, I honestly have no idea as I never done things this way, only manually. Have you tried using the generic method?