Data Validation Telerik UI for WPF

I know this is another year older – but I agree with drasto. Using exceptions for validation is a bad habit and should be avoided wherever possible.

We also can use Validation.Errors attached property to retrieve error message. The binding object has a validation tools collection which is used to hold the custom validation rules. Finally, the binding is set to the TextBox control which is added to the DockPanel control. Similarly, it makes it possible to invalidate a property when setting another property and it also supports setting multiple errors per property and custom error objects of some other type than System.String .

I have a simple UI where I have two fields Name and Mobile Number. And a view model which binds to this UI contains two properties. The data fields of the RadCardView control support data validation of the user input.

OnLostFocus – When setting MaxValidation or MinValidation to OnLostFocus, the value in the DoubleTextBox is validated, when the DoubleTextBox loses the focus. That is, the DoubleTextBox will accept any value, validation will only take Dashboard Design Considerations and Best Practices place after the DoubleTextBox has lost its keyboard focus. After validation, when the value of the DoubleTextBox is greater than the MaxValue or less than the MinValue, the value will be automatically set to MaxValue or MinValue.

Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. I agree to the creation of a Syncfusion account in my name and to be contacted regarding this message. When value of MinimumNumberDecimalDigits, MaximumNumberDecimalDigits and NumberDecimalDigits properties are specified, NumberDecimalDigits property takes high precedence and updates the text of DoubleTextBox property.

• As well as the interface approaches, which are defined in the ViewModel, you can also define a validation rule and reuse it by specifying the rule in the binding of the required properties.
• Main issue here is with accessibility as some people may not even notice a color change.
• The validation style is defined in the App.XAML file which can be adjusted easily.
• I have a simple UI where I have two fields Name and Mobile Number.

With textbox, the error will show after next inserted character. It means you can only enter less then or equal to 4 digit number. By doing this you can define range of numbers in textbox.

WPF Validation: How to Validate the Whole Form on the Button Click

Each of them presents a different style of presenting the occurred error to the user. When an error occurs on the data binding the attached property Validation.HasError property is set to true on the target element of the data binding process (in our case it’s TextBox element). So we can use this property to indicate if the value entered by the user is invalid.

I do not think that the little extra work of instantiating an exception would impose a performance hit here. You can remove the check for ‘.’ (and the subsequent check for more than one ‘.’) if your TextBox shouldn’t allow decimal places. You could also add a check for ‘-’ if your TextBox should allow negative values. You have not detailed the User Experience that would be present.

The adorned element in this case is the TextBox control itself and you include an AdornedElementPlaceholder in the control template where you want to leave space for it. The template above will cause the error message to be displayed in a TextBlock below the TextBox. Note that the TextBlock will appear on top of any elements that are located right below the TextBox as adorners are always visually on top. DevExpress Data Editors validate user input when input masks are enabled. Masks let you specify the pattern for input values and users cannot enter text which is not permitted. In masked mode, entered values always match the edit masks.

form-validation-of-input-control-in-wpf-application

The Label will be used to display the error message to the user. MaxValueOnExceedMaxDigit – When you give input greater than specified maximum limit, MaxValueOnExceedMaxDigit Software development articles for dummies property will decide either it should retain the old value or reset to maximum limit that is specified. For example, if MaxValue is set to 100 and you are trying to input 200.

Our mission is to validate the TextBox on lost focus event hence, we are going to implement the TextBox lost focus event. MinValueOnExceedMinDigit – When you give input less than specified minimum limit, MinValueOnExceedMinDigit property will decide either it should retain the old value or reset to minimum limit that is specified. For example, if MinValue is set to 200 and the Value is 205 and you are trying change the value to 20. Value will changed to 200 when MinValueOnExceedMinDigit is true.

We can change the maximum and minimum limits by using the MinValue property and MaxValue property. If the binding has a converter, its ConvertBack method gets called. The POCO View Models can automatically implement the IDataErrorInfo interface based on the specified Data Annotation Attributes attributes. Refer to the Automatic IDataErrorInfo Implementation section for more information.

Please provide an original answer if possible, rather than referring to a URL. I’ve read a lot of possible solutions involving event handlers, but I haven’t come across anyone discussing the possibility of doing all my validation in the ValidationRule. In the C# code snippet you can notice that I am checking for the valid phone number using the ValidatePhone() method. This method is in turn throwing the exception if the phone is not in valid format. Let me say that the larger the form it the less your conversion rate will be, forms should be small / short and only capture additional information you have not captured yet. Users are most likely to provide short pieces of the info.

Input Validation

Setting the property to this value means that the value of the source property only gets updated when you explicitly call the BindingExpression.UpdateSource() method in code. You will typically never use this approach in an MVVM application though. You can use the BaseEdit.ValidationErrorTemplate property to change the template of the validation error’s content, and the BaseEdit.ErrorToolTipContentTemplate property to customize the template of the error’s tooltip content. An editor can block focus transition to other controls until a valid value is entered (see BaseEdit.InvalidValueBehavior). You can call the BaseEdit.DoValidate method to validate user input at any moment. Exceptions are one of the only ways to catch some types of input invalidations and are explicitly used it MS docs.

We have a Windows desktop application that has many textboxes contained in a dialog that need to be validated, each one differently (needs to be a number, needs to be between 2 numbers, needs to be greater than zero, etc.). Your example does what I want, except, I need to do it all in code. (My WPF window has a varying number of TextBoxes depending Global Messaging Service Provider on several factors.) So far, I’ve been baffled by how to set the bindings, paths, updateTriggerSources in code. MinValidation is set to OnKeyPress, it cannot let to enter a value less than the MinValue. If try to enter a value less than the MinValue, then the MinValue will set to the Value property because MinValueOnExceedMinDigit is set to true.

A common requirement for any user interface application that accepts user input is to validate the entered information to ensure that it has the expected format and type for the back-end to be able to accept and persist it. It also contains an example that shows how you can validate data using data annotations. The method returns true or false depending on whether the validation succeeded or not and it also returns a collection of error messages as an out parameter. Declaring an argument as out is useful when you want the method to return multiple values. As you can see in the above code snippet we defined TextBox styles in the Window resources section. As I mentioned before to indicate if we should show error message we’re using attached Validation.HasError property.

Implement Validation for WPF TextBoxes

In a case where there is a dependency between fields and if changing the value forces another field to update, again notify the user about the change to a previous field they filled out. In that case the border changes to read and you can have a tooltip. Even if you don’t use WPF it is a behavior many users are used to. MessageBoxes are not very friendly in my opinion, I use them only when errors are severe and I gues you need Messagebox.Show from code behind to show them.

Also this is UI, single input validation, not entire objects. One of the advantage of this validation is that is discards the value of the property before being set to the property variable and don’t store the value in the member variable of class. In this article I will discuss all the ways in which we can validate data in the WPF application. The various WPF validation techniques are as following.

This gives us an extensive framework where we can add multiple validation rules easily without having to change our application. In ASP.NET MVC the default model binder supports validation of properties using DataAnnotations attributes. It basically enables you to move the validation logic from the controller to the model which effectively makes it easier to write unit tests for the the controller actions. Note that the ValidationStep property needs to be set to RawProposedValue, either explicitly or implictly by using the default value, for the rule to be applied before the default conversion occurs. INotifyDataError is also used to validate the data changes and notify if there is any error in the data. This interface notifies the view by raising the ‘ErrorChanged’ event.