I have a TextBox in my WPF app. I have defined a ControlTemplate for validation error as follows:
<ControlTemplate x:Key="validationTemplate">
<DockPanel LastChildFill="True">
<TextBlock DockPanel.Dock="Bottom" Text="Invalid Input: "></TextBlock>
<AdornedElementPlaceholder />
</DockPanel>
</ControlTemplate>
My TextBox is as follows :
<TextBox Validation.ErrorTemplate="{StaticResource validationTemplate}">
<TextBox.Text>
<Binding Path="TEXT1" ValidatesOnDataErrors="True" validatesOnExceptions="True">
</Binding>
</TextBox.Text>
</TextBox>
Now if my TextBox is added ValidationRule and then I validate there, the error template applies correctly. But I cant do that because of some other problem.
So I have to validate the content of TextBox in PreviewLostKeyboardFocus. I am validating the TextBox. Now I want to set the error template for the TextBox in code behind but I am unable to do it !!
I tried this but it does not work as intented::
private void blockTextBox_PreviewLostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
TextBox txtBox = sender as TextBox;
txtBox.Template = this.FindResource("validationTemplate") as ControlTemplate;
//this behaves strange; it removes the TextBox and places the ErrorTemplate.
//I want it to behave like the way WPF does internally wherein it places
//the error template around TExtBox
}
Question 1: I want to know how to add the error template to TextBox
Question 2: I want to know how do I set the error message of the control template from code. Like for example, I want to change the default error message "Invalid Input: " to "Invalid Input: Please enter correct input".
I want to do the above mentioned things in code behind only !!!!
EDIT 1:
The problem is how do I set from code behind Validation.HasError as true because I am not using any Validator. (or what should I set from code behind that ValidationTemplate gets applied ?? ))
EDIT 2:
I am doing XML binding so there is no way I can implement IDataErrorInfo !! I want to achieve this from code behind only!! Is there a way to set Validation.HasError from code behind ??
To set "Validation.HasError" in code behind you can use the Validation.MarkInvalid method
private void blockTextBox_PreviewLostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
TextBox txtBox = sender as TextBox;
//...
BindingExpression bindingExpression =
BindingOperations.GetBindingExpression(txtBox, TextBox.TextProperty);
BindingExpressionBase bindingExpressionBase =
BindingOperations.GetBindingExpressionBase(txtBox, TextBox.TextProperty);
ValidationError validationError =
new ValidationError(new ExceptionValidationRule(), bindingExpression);
Validation.MarkInvalid(bindingExpressionBase, validationError);
}
To unset the value you use
Validation.ClearInvalid
Thanks to for the wonderful link he suggested me.My code goes somewhat this way
String errorMessage = GetFormattedErrorMessage(toolTip.Range, range);
ValidationError validationError = new ValidationError(new DummyValidator(),
txtBox.GetBindingExpression(TextBox.TextProperty));
Validation.MarkInvalid(txtBox.GetBindingExpression(TextBox.TextProperty), validationError);
validationError.ErrorContent = errorMessage;
Validation.SetErrorTemplate(txtBox, GetErrorTemplate(errorMessage));
Validation.SetErrorTemplate(txtBox, this.FindResource("validationTemplate") as ControlTemplate);
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