The UpdateSourceTrigger property

Wpf binding in code not updating

As promised I found some

It means that the source value will be updated each time the destination control loses focus. The Mode of the binding is set to TwoWay because we want to update the source whenever a change occurs in the target.

Varies from control to

The UpdateSourceTrigger property In the previous article we saw how changes in a TextBox was not immediately sent back to the source. As you may know, when we use TwoWay as the mode of our binding, any change that takes place in the target of the binding affects the value of the source. Actually, this is the same code in all of our examples.

One TextBlock will do so without the tweak to update binding therefore the ViewModel wont be updated. As the name implies, this means that whenever there is a change in the Text property of the second TextBox, the Text property of the first TextBox gets updated immediately. And finally, the UpdateSourceTrigger property of the binding is set to Default. For example, as you type characters in a TextBox which is the target of a binding, the source is updated, too. This means that the Text property of the TextBox changes as you type characters.

And finally our last example is about setting the UpdateSourceTrigger property to Explicit. Just make sure that you don't update the source value more often than you actually need to.

Futhermore I do not know why people avoid using code behind. The first two has already been described, while the last one simply means that the update has to be pushed manually through to occur, using a call to UpdateSource on the Binding. If you want the full control, you can use the Explicit value and then do the updates manually, but this does take a bit of the fun out of working with data bindings.

Just make sure that you

Varies from control to control. As promised I found some time to take a look at this. This behavior is controlled by a property on the binding called UpdateSourceTrigger.

Still it is a tweak and like I mentioned the animations shall stay animations. And finally, the UpdateSource method of be is called which updates the source of the binding explicitly.

Now, the question is when to update the source with the changes that has taken place in the target. For those situations where you need more control of the process, this property will definitely help though.

Wpf DatePicker text not updating after binding source update

This behavior is controlledStill it is a

For all of these approaches I have written some code to help you better understand them. Summary The UpdateSourceTrigger property of a binding controls how and when a changed value is sent back to the source.

And finally ourAnd finally the UpdateSource method

For that reason, I have added a button next to the TextBox, which will update the source value on demand. Default is, obviously, the default value of the UpdateSourceTrigger. The another will implement a small hack how to update binding and set the animated value as current value. Best example is all those event handlers who may only be defined in code behind. Means that when a change occurs in the target, the source is updated immediately.

The Button which is declared after the second TextBox is responsible for doing this. For TextBox, for example, it means when the LostFocus event of the target of the binding occurs.