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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.
This post is about how data validation works in WPF and the different validation options there are available including implementing custom Validation Rules and using the In a typical WPF application that uses the MVVM (Model-View-View Model) design pattern, a dependency property of a user interface control in a XAML-defined view uses data binding to bind to some data returned by a CLR property of the view model.
could not be converted” when the conversion of the string value to an int fails, you may want to customize it.
You can do this by implementing a custom validation rule and associate this with the object at any given step, any errors that were added to the Validation.
In a MVVM WPF application, the view model acts as the window’s Data Context: This means that that all controls inside the window will inherit its Data Context unless some parent element of a control overrides this by setting its own Data Context property.
NET Framework 4.5 and the Windows Runtime (Win RT) – and update the dictionary based on the result of the validation: For the view to be able show more than a single error message you have to make some changes to the Validation. You typically use an Items Control present a collection of items in XAML: As mentioned, you can also return error objects of a any type from the Get Errors method and this can be very useful when you want to present custom error reporting in the view.Setting the property to this value means that the value of the source property only gets updated when you explicitly call the Binding Expression. You will typically never use this approach in an MVVM application though.