Wpf textblock text binding not updating
It would be better to govern how often the binding source’s new values are pushed to the binding target. One solution is to create a value converter which governs the data flow between source and target.
The converter can keep a time stamp which it uses to determine when the new source values can be pushed to the target.
Binding inside your user control isn’t exactly obvious either.
The reason is, you get an error when you attempt to set the data context of the user control.
Conversely, user controls cannot be templated as the XAML is embedded. Net developer then you will likely start with simple CLR properties. Like this: Setting such a property is a snap, and it works just fine. A data binding target MUST be a dependency property.
The simplest user control might look like this: The simplest use of a user control would be like this: In the code above, I simply declare the user control and the rest is done for me. You can reference it in the code behind or you can reference it in the XAML. Once we know the property must be a dependency property (which simply means the property must be backed by a dependency property object) we can start to build it out: In the code above, we create our Text property as a dependency property and we introduce a reusable method called Set Value Dp() which uses the Call Member Name introduced in . Call Member Name let’s you reference your property name without creating a literal string in your code-behind.
User controls are a great way couple logic and XAML in an encapsulated way. A user control contrasts with a custom control in that a custom control contains no XAML. And though it says you may safely continue, it doesn’t continue safely at all. It means the binding target isn’t a dependency property!
You can reuse a user control over and over and the logic is isolated from the general flow of your program. Custom control can be (and is sometimes are required to be) templated (for example, a Data Template). This is confusing to XAML developers because they are accustomed to binding to CLR properties that implement INotify Property Changed in their view models. A data binding source source CAN be a CLR-type property.
Please note: the data context property of the user control inherits from the parent. But user controls don’t anticipate a data context type. Writing to one writes to the other and the dependency property itself keeps the coalesced value.With WPF this is done easily by setting the Update Source Trigger property to Property Changed in the Binding definition, unfortunately this is not available for Silverlight.A workaround that I found for this was to add a Key Up event to the required Text Box and update the binding in code behind.If the binding is setup correctly and the view model implements the interface to provide notifications when the data changes, the changes are automatically reflected in the elements in the view that are bound to it.Correspondingly, an underlying data value in the view model is automatically updated when the user modifies the bound value in the view.