CODEWITHSUNDEEP
c#wpfxaml
GSP
GSP

Reputation: 584

wpf LostFocus event of Textbox

This is my xaml structure

<StackPanel>
  <m:TextBoxWithEllipsis IsEllipsisEnabled="True"
     Name="A"
     LostFocus="text_LostFocus"/>
  <m:TextBoxWithEllipsis IsEllipsisEnabled="True"
     Name="B"
     LostFocus="text_LostFocus"/>
</StackPanel>

=> This structure can loop more. Such as:

<StackPanel>
  <m:TextBoxWithEllipsis IsEllipsisEnabled="True"
     Name="A"
     LostFocus="text_LostFocus"/>
  <m:TextBoxWithEllipsis IsEllipsisEnabled="True"
     Name="B"
     LostFocus="text_LostFocus"/>
</StackPanel>
<StackPanel>
  <m:TextBoxWithEllipsis IsEllipsisEnabled="True"
     Name="A"
     LostFocus="text_LostFocus"/>
  <m:TextBoxWithEllipsis IsEllipsisEnabled="True"
     Name="B"
     LostFocus="text_LostFocus"/>
</StackPanel>

In .cs file, I define event lost focus as below

private void text_LostFocus(object sender, RoutedEventArgs e)
{
   TextBox textbox = ((TextBox)sender);
   if (textbox.Text.Trim().Length == 0)
   {
      System.Windows.Forms.DialogResult result1 = System.Windows.Forms.MessageBox.Show("Empty string!", "Warning",
                 System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Exclamation);
                textbox.Dispatcher.BeginInvoke((Action)(() => { textbox.Focus(); }));
       return;
    }
    textbox.ScrollToHome();
}

The problem: If there are >= 2 textbox having value is empty ("").

  1. I click first empty textbox => I don't enter any characters.
  2. Then I click second empty textbox.

==> Program always show the message box => If I click OK button, It show another. It occur forever. I can't close the program.

Question: If I have >= 2 empty textbox and I do same as problem above. How can I change the function text_LostFocus to solve the problem???

DEFAULT:

Upvotes: 2

Views: 38757

Answers (1)

Il Vic
Il Vic

Reputation: 5666

I wouldn't use a MessageBox if I were you. WPF has a very good "binding validation framework" (take a look here for a very good tutorial). Otherwise I would create a "warning" label located close each textbox:

<StackPanel>
  <m:TextBoxWithEllipsis IsEllipsisEnabled="True"
     Name="A"
     LostFocus="text_LostFocus"/>
  <TextBlock Name="AWarning" Foreground="Red" />
  <m:TextBoxWithEllipsis IsEllipsisEnabled="True"
     Name="B"
     LostFocus="text_LostFocus"/>
  <TextBlock Name="BWarning" Foreground="Red" />
</StackPanel>

Then in the code-behind:

private void text_LostFocus(object sender, RoutedEventArgs e)
{
    TextBox textBox = ((TextBox)sender);
    TextBlock textBlock = FindName(String.Concat(textBox.Name, "Warning")) as TextBlock;
    textBlock.Text = String.IsNullOrWhiteSpace(textBox.Text) ? "Empty string!" : String.Empty;
}

Upvotes: 7

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