Add a method to Binder to check if a specific Binding changed

[felix-office]

Describe your motivation

Inside our binder, we use a custom field for address input. If the values in it change, I need to persist the new address object before I can persist the binder bean. So I need to be able to find out if the address field has changed. Binder#hasChanged() only tells me if any field of the binder has changed.

Describe the solution you'd like

The binder already has a set of changed bindings https://github.com/vaadin/framework/blob/master/server/src/main/java/com/vaadin/data/Binder.java#L1536.
We can use this to add a method hasChanges(Binding<BEAN, ?> binding).

In the perfect word it would also remove the "change state" if the value is changed back to the original one but I don't see that this is currently a feature of the Binder.

Describe alternatives you've considered

Building the logic myself using the value change listener.

Additional context

Is there anything else you can add about the proposal?

[benedikt-roth]

Hello, is this still needed? I would like to contribute to the project and can have a look at it.

[knoobie]

Still up to grab

[benedikt-roth]

Okay, can you please assign this to me?

One more clarification: Is this change supposed to be done in flow or the framework repo? I assume that is to be done in flow.

Best,
Beneidkt

[knoobie]

@mshabarov sounds like you should answer this :)

[mshabarov]

@benedikt-roth thank you very much for willing contribute! 👍
Yes, this is still good to have in Flow.
This feature should be contributed to Vaadin Flow repo, to the Binder class (not necessary only there, but this is a main API).

Vaadin Flow team will review it as soon as we can. Feel free to post even a draft PR or incomplete PR, will try to help.

@knoobie thanks for pinging me, I missed the notification for this.

[benedikt-roth]

☝🏼 this is my proposal. Let me know what you think.

I was wondering whether there needs to be some additional check to see whether the provided binding is associated with the binder at all. What do you think?

[vaadin-bot]

This ticket/PR has been released with Vaadin 24.3.0.alpha1 and is also targeting the upcoming stable 24.3.0 version.