Validating data in vb net
if you are typing a letter into a Text Box bound to a source property of type int: The actual message that is describing the error is stored in the Error Content property of a objects in it, another attached property named Validation. To be able to see the error messages in the view you can replace the default control template that draws the red border around the element with your own custom template by setting the Validation.
Error Template attached property of the control: Note that the Validation.
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.
Errors attached property of the bound element during that step in a previous validation procedure are removed. Errors collection is also cleared when a valid value transfer occurs.
WPF ships with two built-in concrete implementations of the object to the Validation.
The latter can for example be very useful for bindings in Styles and Control Templates and when you want to bind to some property in a parent element.
The Mode property of the , which is the default for the Text property of the Text Box control, the text you type into the Text Box does not update the source property until the control loses focus which happens when you click away from it. the setter for the bound property of the Data Context to get called, as the user is typing into the Text Box you set the Update Source Trigger property to enumeration.