Vb net datagrid validating
If the source of a two-way binding implements the interface and the Validates On Notify Data Errors property of the binding is set to true (which it is by default), the WPF 4.5 binding engine automatically monitors the Errors Changed event and calls the Get Errors method to retrieve the updated errors once the event is raised from the source object provided that the Has Errors property returns true.Below is an example of a simple service with a single method that validates a username by first querying a database to determine whether it is already in use or not and then checks the length of it and finally determines whether it contains any illegal characters by using a regular expression.
Besides inheriting and setting the Data Context property on an element directly you can also specify a binding source using the Element Name property, used when you want to bind to some other element, or the Relative Source property.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.If you want to bind a view model property of a specific type to a dependency property in the view of a different type you may need to implement a custom converter class by implementing the interface and setting the Converter property of the binding to an instance of this.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.