Accessing WPF control validation rules from code

Question

XAML:

  
      
          
              
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Answer 1

Validation.HasError is an attached property so you can check it for textboxMin like this

void buttonOK_Click(object sender, RoutedEventArgs e)
{
    if (Validation.GetHasError(textboxMin) == true)
         return;
}

To run all ValidationRules for the TextProperty in code behind you can get the BindingExpression and call UpdateSource

BindingExpression be = textboxMin.GetBindingExpression(TextBox.TextProperty);
be.UpdateSource();

Update

It will take some steps to achieve the binding to disable the button if any validation occurs.

First, make sure all bindings add NotifyOnValidationError="True". Example

Then we hook up an EventHandler to the Validation.Error event in the Window.

And in code behind we add and remove the validation errors in an observablecollection as they come and go

public ObservableCollection ValidationErrors { get; private set; } 
private void Window_Error(object sender, ValidationErrorEventArgs e)
{
    if (e.Action == ValidationErrorEventAction.Added)
    {
        ValidationErrors.Add(e.Error);
    }
    else
    {
        ValidationErrors.Remove(e.Error);
    }
}

And then we can bind IsEnabled of the Button to ValidationErrors.Count like this