New methods to ease migration to onConfigure
--------------------------------------------
Key: WICKET-3568
URL: https://issues.apache.org/jira/browse/WICKET-3568
Project: Wicket
Issue Type: Improvement
Components: wicket-core
Affects Versions: 1.5-RC2, 1.4.16
Reporter: Emond Papegaaij
We are trying to migrate our projects from overriding isVisible and isEnabled
to the new onConfigure method, but are having some problems with the new API.
I'll start with explaining the old situation. We find it good practice to
always call super.isVisible() in an overriding isVisible method. A typical
implementation would look like this:
public class MyComponent extends WebMarkupContainer {
public boolean isVisible() {
return super.isVisible() && isConditionSatisfied();
}
}
Doing things this way, ensures the component will never be visible when the
condition is not satisfied, nor when the component is explicitly hidden with
setVisible(false).
Trying to convert this to the new API, we started with:
public class MyComponent extends WebMarkupContainer {
protected void onConfigure() {
super.onConfigure();
setVisible(isVisible() && isConditionSatisfied());
}
}
However, we soon realized this will not work because a hidden component can
never become visible again. Even when the condition is satisfied, isVisible()
will still be false, causing the component to remain hidden. Therefore, our
second attempt was to remove the call to isVisible():
public class MyComponent extends WebMarkupContainer {
protected void onConfigure() {
super.onConfigure();
setVisible(isConditionSatisfied());
}
}
This, however, suffers from another problem: manual setVisible(...) calls are
now ignored. The visibility flag is always overridden by onConfigure. On our
third attempt, we decided to use the visibilityAllowed flag for onConfigure,
like this:
public class MyComponent extends WebMarkupContainer {
protected void onConfigure() {
super.onConfigure();
setVisibilityAllowed(isConditionSatisfied());
}
}
This works great. It mixes with calls to setVisible. It even mixes well with
isVisible overrides in subclasses. However, this approach only works for
component visibility. There is no setEnabledAllowed. There is a
isEnableAllowed(), but it is security related (the counterpart of
isRenderAllowed()).
Would it be possible to add a new property to Component (both in 1.4 and 1.5):
enabledAllowed? This property would have a final getter (isEnabledAllowed) and
setter (setEnabledAllowed), just as with visibilityAllowed. The naming of
isEnableAllowed() would be a bit unfortunate, but I don't think that method
can be changed. It is part of the public API. This new property would make it
significantly easier to move to onConfigure.
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