| E4 DI in "onAction" methods [message #1384676] |
Fri, 30 May 2014 05:20  |
Eclipse User |
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Hi,
I'm looking for a good solution for the following problem:
Asssume you have an FXML file with a combo box and an associated onAction() method like <ComboBox ... onAction="#handleSelection" />
The controller's handleSelection() method uses an instance of type Foo that was injected by E4 into the controller during its instantiation.
Now assume you cannot guarantee there is a Foo instance available at instantiation time, so you would like to inject it into the handleSelection() method, as this is the point in time where you actually need the instance:
@FXML
@Inject
public void handleSelection(Foo foo) {
...
}
As you might expect, this code cannot be parsed by the FXML loader:
javafx.fxml.LoadException: Error resolving onAction='#handleSelection', either the event handler is not in the Namespace or there is an error in the script.
What would be a good solution for this problem at the interface of JavaFX and E4? Of course, you could use ContextInjectionFactory.inject() or maybe call an E4 command programmatically, but these approaches don't seem very elegant.
Thanks,
Uwe
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| Re: E4 DI in "onAction" methods [message #1384680 is a reply to message #1384676] |
Fri, 30 May 2014 06:20  |
| Eclipse User |
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Well you could declare your stuff as:
private Foo foo;
@Optional
@Inject
public void setFoo(Foo foo) {
this.foo = foo;
}
@FXML
public void handleSelection() {
if(foo != null) {
// ....
}
}
On 30.05.14 10:20, Uwe San wrote:
> Hi,
>
> I'm looking for a good solution for the following problem:
>
> Asssume you have an FXML file with a combo box and an associated
> onAction() method like <ComboBox ... onAction="#handleSelection" />
> The controller's handleSelection() method uses an instance of type Foo
> that was injected by E4 into the controller during its instantiation.
>
> Now assume you cannot guarantee there is a Foo instance available at
> instantiation time, so you would like to inject it into the
> handleSelection() method, as this is the point in time where you
> actually need the instance:
>
> @FXML
> @Inject
> public void handleSelection(Foo foo) {
> ..
> }
>
> As you might expect, this code cannot be parsed by the FXML loader:
> javafx.fxml.LoadException: Error resolving onAction='#handleSelection',
> either the event handler is not in the Namespace or there is an error in
> the script.
> What would be a good solution for this problem at the interface of
> JavaFX and E4? Of course, you could use ContextInjectionFactory.inject()
> or maybe call an E4 command programmatically, but these approaches don't
> seem very elegant.
>
> Thanks,
> Uwe
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| Re: E4 DI in "onAction" methods [message #1384682 is a reply to message #1384680] |
Fri, 30 May 2014 06:37 |
| Eclipse User |
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This would be a working approach, but it comes with one drawback: the code does not clearly state that the Foo instance is needed specifically for the handleSelection() method. The controller needs to have a foo field when foo could simply be a method parameter.
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