|
| Re: Inject values into fields when class instantiated in my code [message #1752669 is a reply to message #1752661] |
Wed, 25 January 2017 21:50   |
 Erdal Karaca
Messages: 854
Registered: July 2009 |
Senior Member |
|
|
That is possible using
IEclipseContext context = ...;
handler = ContextInjectionFactory.make(OpenProjectComponentHandler.class, eclipseContext);
ContextInjectionFactory.invoke(handler, Execute.class, eclipseContext);
But, I think, it would be better to extract the executed logic into a utility method that you can call outside DI and just delegat to within DI.
Ken Keefe wrote on Wed, 25 January 2017 22:34I'm trying to figure out how to correctly inject values into a handler when it is created in my own custom code. Here is the handler code:
public class OpenProjectComponentHandler {
@Inject
private MApplication application;
@Inject
private EModelService modelService;
@Execute
public Object execute(@Named(IServiceConstants.ACTIVE_SELECTION) ISelection sel) {
/* Code that uses modelService and application here */
return null;
}
@CanExecute
public boolean canExecute() {
return true;
}
}
Now, when a menu item click triggers the call to this handler, application and modelService are injected as I'd expect. But, I also want to call this handler from other custom code like this:
OpenProjectComponentHandler handle = new OpenProjectComponentHandler();
handle.execute(new StructuredSelection(o));
When I call the handler using my own code, the fields have nothing injected into them.
|
|
|
|
| Re: Inject values into fields when class instantiated in my code [message #1752673 is a reply to message #1752661] |
Wed, 25 January 2017 21:57 |
Patrik Suzzi
Messages: 2
Registered: February 2018 |
Junior Member |
|
|
I generally avoid field injection, because I can not easily predict the values of the injected fields.
I tend to use injected constructors and injected methods in general, as I find more predictable the way I can obtain values injecting parameters.
In the code snippet below, you can see how I transformed your initial code snippet in a way that is easier to use and less prone to errors. In particular, note that:
1. I injected the needed parameters in the @Execute method. So doing, Eclipse injects the actual instances for "IEclipseContext ", "EModelService" and "MApplication" each time the method is called.
2. I added another method where @Optional @Named(IServiceConstants.ACTIVE_SELECTION) is injected. This means that this method is automagically executed each time the ACTIVE_SELECTION changes.
public class OpenProjectComponentHandler {
private MApplication application;
private EModelService modelService;
private StructuredSelection selection;
@Execute
public Object execute(IEclipseContext context, EModelService modelService, MApplication application) {
// you can keep references to the injected objects
this.application = application;
this.modelService = modelService;
// execute code using modelService application and context
return null;
}
@CanExecute
public boolean canExecute() {
return true;
}
@Inject
@Optional
public void executeOnSelection(
@Optional @Named(IServiceConstants.ACTIVE_SELECTION) StructuredSelection selection) {
// you can keep reference to the injected object
this.selection = selection;
// here you execute your code when the selection changes
}
}
In case you need more information, please read about dependency injection in Eclipse 4, and about the difference between field injection and parameter injection.
- as an example: http://eclipsesource.com/blogs/tutorials/eclipse-4-e4-tutorial-part-4-dependency-injection-basics/
Also, you can check for one of the many tutorials available on the web.
Kind Regards,
Ing. Patrik Suzzi
Consultant Software Engineer,
Eclipse Platform Committer
https://about.me/psuzzi
[Updated on: Thu, 26 January 2017 22:55] by Moderator Report message to a moderator |
|
|
Powered by
FUDForum. Page generated in 0.03281 seconds
] 
Search
Help
Register
Login
Home
