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Wpf datatrigger binding not updating

To see how all of these options work, I have updated the example from the previous chapter to show you all of them: As you can see, each of the three textboxes now uses a different Update Source Trigger.

The first one is set to Explicit, which basically means that the source won't be updated unless you manually do it.

In the previous article we saw how changes in a Text Box was not immediately sent back to the source.

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.

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The third and last Text Box uses the Property Changed value, which means that the source value will be updated each time the bound property changes, which it does in this case as soon as the text changes.

Try running the example on your own machine and see how the three textboxes act completely different: The first value doesn't update before you click the button, the second value isn't updated until you leave the Text Box, while the third value updates automatically on each keystroke, text change etc.

Have you ever noticed that if you try to modify a property in data trigger which is already specified in the control itself then data trigger won't have any effect even when data trigger conditions are met.

Consider the following use case in which you've a textbox and a trigger defined on that.This behavior is controlled by a property on the binding called Update Source Trigger.It defaults to the value "Default", which basically means that the source is updated based on the property that you bind to.The other options are Property Changed, Lost Focus and Explicit.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 Update Source on the Binding.The Update Source Trigger property of a binding controls how and when a changed value is sent back to the source.However, since WPF is pretty good at controlling this for you, the default value should suffice for most cases, where you will get the best mix of a constantly updated UI and good performance.It watches a specific property on the owner control and when that property has a value that matches the specified value, properties can change.In theory this might sound a bit complicated, but it's actually quite simple once we turn theory into an example: In this style, we set the Foreground property to blue, to make it look like a hyperlink.In above example even if Property A becomes true then text of the textblock will remain "Default Value" instead of "Updated Value".Fix: In order to work it properly, you need to specify the "Default Value" in style not with the control.

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