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List:       openjdk-openjfx-dev
Subject:    Re: Bidirectional binding enhancement
From:       Tom Schindl <tom.schindl () bestsolution ! at>
Date:       2021-11-10 7:51:23
Message-ID: 36c12f2f-1f8d-7457-e191-aa34638ffecf () bestsolution ! at
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Hi,

We had something very similar in Eclipse-Databinding so I think 
something like that makes a lot of sense but I wonder how you want to 
implement this FOCUS, ACTION.

Another thing we had was a delayed-Observable where the sync only 
happened if there hasn't been a change with a user specified timeout 
which fairly nice to implement undo/redo like stuff eg in TextAreas.

As you don't have access to Node in javafx.base I'm not sure how you 
want to implement the trigger stuff. Just in case in Eclipse-Databinding 
world we had stuff like this in a module (in this case OSGi-Bundle) who 
has access to both the core-API and the ui-API.

Tom

Am 10.11.21 um 06:45 schrieb Michael Strauß:
> JavaFX developers routinely use programming patterns like MVC, MVP, or
> MVVM to separate views from their associated business logic. Bindings
> can be used to connect the values of UI controls (like Label or
> TextField) to properties on a business logic class.
> 
> A typical (simplified) scenario may look like this:
> 
> var valueField = new TextField();
> valueField.textProperty().bindBidirectional(businessLogic.valueProperty());
> 
> The business logic class may perform data validation or other actions
> on the value that was entered in the TextField. However, in many
> cases, it is neither necessary nor desirable for the binding to update
> the business-layer property on every single change (i.e. every single
> character that was typed by a user). For example, if a business rule
> verifies that the data entered by a user is formatted in a specific
> way, it's usually not a great experience to yield a validation error
> before the user has finished typing. Instead, it's often better to
> wait until the user has significantly interacted with a UI control
> before running business logic.
> 
> For this reason, I propose to add a new type of binding to the
> javafx.beans.binding.Bindings class:
> 
> void bindBidirectional(Property<T> target, Property<T> source,
> UpdateSourceTrigger trigger)
> 
> UpdateSourceTrigger is an enumeration that allows developers to
> specify the condition on which changes of the target property will
> update the source property. Its values are:
> 
> DEFAULT: Updates the source property on every change (this is the
> default behavior of bidirectional bindings).
> FOCUS: Updates the source property when the UI control loses input focus.
> ACTION: Updates the source property when the UI control loses input
> focus or when it receives an ActionEvent (in the case of TextField,
> this corresponds to the ENTER key).
> 
> Note that this setting only applies to changes of the target property.
> When the source property is changed instead, the target property is
> always immediately updated.
> 
> Any feedback on this proposal is appreciated.
> 

-- 
Tom Schindl - CTO
BestSolution.at EDV Systemhaus GmbH
Salurner Straße 15, A-6020 Innsbruck
Phone: ++43 (0)512 935834
http://www.BestSolution.at - http://efxclipse.org
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