如果任何控件已更改，则引发事件WPF

Question

I want make validation in my WPF application. And the approach I want to use is I want to take custom action if any value of my controls has been changed.

How I can do that suppose I have control like this

<TextBox x:Name="TextBox1" Text="{Binding Path=Box1,UpdateSourceTrigger=PropertyChanged}" />
<TextBox x:Name="TextBox2" Text="{Binding Path=Box2,UpdateSourceTrigger=PropertyChanged}" />

And If user change the value one of that control I want to create custom action for example (For my thinking )

private void Window_Controls_Property_Changed(object sender,RoutedEventArgs e){
  if(((Control)sender)=="TextBox1")
    MessageBox.Show("Show message here of validation some control","Attention",MessageBoxButton.OK);
}

I'm still confusing combine the INotifyPropertyChanged or ValidationRule with displaying error what I want with MessageBox. I'm still newbie using this kind of features.

I have read many articles about INotifyPropertyChanged or ValidationRule but I'm still don't know how to get the custom action like I said before. And the custom validation may use another textbpx value to validate with the other textbox.

Any helps?..

Answer 1

You can register the handler on the Container that hosts your TextBox's. Like this:

<StackPanel TextBox.LostFocus="TextBox_OnLostFocus">
    <TextBox x:Name="TextBox1" Text="{Binding Path=Box1,UpdateSourceTrigger=PropertyChanged}" />
    <TextBox x:Name="TextBox2" Text="{Binding Path=Box2,UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>

This way the same handler will be used for all TextBox's and you can query e.Source to find out which TextBox triggered the event.

Answer 2

for Validation in mvvm you can take IDataErrorInfo. there are examples all over the net.

and if you really whant to do some special action when a property in your viewmodel change, you can simply subscribe to your own viewmodel PropertyChanged event and handle your stuff

Answer 3

You may want to read this block post about BindingGroups and validation (and this related blog post ). They show you how you can validate multiple controls at once using custom validation rules.

Answer 4

<TextBox HorizontalAlignment="Left" LostFocus="OnLostFocus"/>

Here's an easy way. Validate using the LostFocus Event in WPF

private void TextBox_LostFocus_1(object sender, RoutedEventArgs e) {
        var thisTextBox = (TextBox)sender;
        if (thisTextBox.Text == "") {
            MessageBox.Show("Validate!");
        }
    }