Bugzilla – Full Text Bug Listing
| Summary: | [DataBinding] Databinding between java.io.File#path and Text control doesn't work | ||
|---|---|---|---|
| Product: | [Eclipse Project] Platform | Reporter: | Sascha Becher <becher-sascha> |
| Component: | UI | Assignee: | Platform UI Triaged <platform-ui-triaged> |
| Status: | RESOLVED WORKSFORME | QA Contact: | Matthew Hall <qualidafial> |
| Severity: | enhancement | ||
| Priority: | P3 | CC: | mechko, prakash |
| Version: | 3.7 | ||
| Target Milestone: | --- | ||
| Hardware: | PC | ||
| OS: | Windows 7 | ||
| Whiteboard: | |||
Hello Sascha!
My apologies for taking so long to respond to this. I hope my response will still be useful to you.
What you are missing is that you can't simply reassign a new value to the selectedFile variable and have data binding pick it up. You must store that value in another observable, and then observe the path as a detail of that observable:
WritableValue fileObservable = WritableValue.withValueType(File.class);
fileObservable.setValue(selectedFile);
When a new file is selected, you indicate this by replacing the value held by the WritableValue:
fileObservable.setValue(newSelectedFile);
Now, to observe the file path, you must observe it as a *detail* of the parent observable, fileObservable:
IObservableFile filePathObservable =
PojoProperties.value("path").observeDetail(fileObservable);
A "detail" observable is an observable that observes a particular detail of the value of the parent observable--in this case, the file observable. The detail we have chosen to observe is the file's path. So every time we stick a new File object in fileObservable, filePathObservable is updated with the path of that file.
Hope this helps.
Thanks for the explanation! >WritableValue fileObservable = WritableValue.withValueType(File.class); >fileObservable.setValue(selectedFile); upon changing the file: >fileObservable.setValue(newSelectedFile); Since I still have to catch the event that changes the file, I could simply update the UI element that displays the path with java.io.File. I don't see how this makes my code shorter. Maybe my misunderstanding is to still have a private property java.io.File on the value object instead of just having an IObservableValue that wraps the File object. But this would make the code less readable, I'm afraid. > IObservableFile filePathObservable = > PojoProperties.value("path").observeDetail(fileObservable); This line doesn't work for me, no IBeanValueProperty#observeDetail found and no IObserveFile, yet I understand what you are suggesting. |
Build Identifier: File selectedFile = new File("123"); Binding binding = new DataBindingContext().bindValue(SWTObservables.observeText(textControl), PojoObservables.observeValue(selectedFile, "path") new UpdateValueStrategy(UpdateValueStrategy.POLICY_NEVER), new UpdateValueStrategy(UpdateValueStrategy.POLICY_UPDATE)); The binding works only for the first time. The text field shows 123 in the beginning. If selectedFile gets changed and binding.updateModelToTarget(); is being called, the text field doesn't change. I guess, it's because class File doesn't has a setter for the property path. But I have set the UpdateValueStrategy of targetToModel to POLICY_NEVER, so the setter of File#path isn't required at all and no Exception is thrown (if set to POLICY_UPDATE, an exception occurs). I find this misleading, as the UpdateValueStrategy's in both directions suggesting control over this aspect. Reproducible: Always Steps to Reproduce: 1. run example code 2. see details above