Validation rules stack overflow exception when return true

Question

Im using the validation rules as follows,

The problem is when the value is true like if i type aa or LastName(which are the right value and I return true) I got the following error ,if I put in the text box some wrong value there is no error (I see the red boarder), any idea what I miss here?

An unhandled exception of type 'System.StackOverflowException'

Currently the situation is that if I don't use the ValidatesOnTargetUpdated="True" there is no red boarder..

following the validation rules

public class PropertiesMapValidation : ValidationRule
        {
        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
            {
            bool isValid = true;
            var list = new List<String> { "aa", "LastName", "BusinessItem", "BusinessItems" };
            var val = (string)value;
            if (val != null)
                {


            ValidationResult result = null;
            result = isValid
                         ? new ValidationResult(true, null)
                         : new ValidationResult(false,
                                                "The Field are not match");
            return result;
            }
        }

THe xaml

    <TextBox x:Name="FirstName" Grid.Column="4" Margin="0,50,0,0"  Grid.Row="2" Style="{StaticResource tooltipError}" Height="24" Width="148">
        <TextBox.Text>
            <Binding ElementName="FirstName" Path="Text" UpdateSourceTrigger="PropertyChanged">
                <Binding.ValidationRules  >

Rick Love · Accepted Answer · 2014-01-29 09:27:40Z

1

If you want an error for an empty string, you need to fix the if statement:

            if (!string.IsNullOrEmpty(mappedProperty))
            {
                foreach (string item in list)
                {
                    if (item != mappedProperty)
                    {
                        isValid = false;
                    }
                    else
                    {
                        isValid = true;
                        break;
                    }
                }
            }
            else
            {
                isValid = false;
            }

However, your code could use some more declarative syntax by replacing the above code with:

isValid = !string.IsNullOrEmpty(mappedProperty)
    && list.Contains(mappedProperty);

Otherwise, the logic seems valid. The exception seems to be coming from something else.

Update:

The textbox is bound to the FirstName property. When the user enters a new value in the TextBox, it is automatically changing the FirstName.Text property to the new value (after it is varified). This is causing the source to update. Then the validator is revalidating and reupdating the source causing an endless loop - stack overflow.

User Enters a valid value
FirstName is updated (UpdateSourceTrigger="PropertyChanged")
FirstName=value (Property Setter)
FirstName property changed event is fired
TextBox updates itself to the new value
TextBox revalidates (ValidatesOnTargetUpdated="True")
TextBox updates FirstName again
Endless Loop

In your FirstName property setter, first check if the value is different than the current value. If it is different, then update your value and let the PropertyChanged event fire.

This should solve your problem.

edited Jan 29, 2014 at 9:27

answered Jan 29, 2014 at 8:05

Rick Love

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6 Comments

John Jerrby Over a year ago

HI Rick ,Can the problem is coming from this declaration since currently the problem that I use style for text boxes and now even the events are not working for the text box after I define the validation rules .please see the styling in the updated post

John Jerrby Over a year ago

When I debug It I see that when Its true and I do F10 I start the validate method from the begining over and over again.just with F10

Rick Love Over a year ago

Ok, so it seems that the source is being updated when the value is valid. Then the text box is refreshing its value and revalidating the new value, then triggering another update of the source.

John Jerrby Over a year ago

The class of the validation rules is invoked...did you mean to that?

Rick Love Over a year ago

In the bound property setter, you should check to see if the value has changed, then only update your property if it is a different value.

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