[WICKET-1891] AjaxLazyLoadPanel shouldn't call getLoadingComponent(String) in constructor

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.4-M2
• Fix Version/s: 1.4-RC1
• Component/s: wicket-extensions
• Assignee: Igor Vaynberg
• Reporter: Craig McIlwee
• Created: 23/Oct/08 22:08
• Updated: 30/Oct/08 07:00
• Resolved: 30/Oct/08 07:00

Description

Use case:

class MyPanel extends AjaxLazyLoadPanel {
private boolean bool;

public MyPanel(String id, boolean bool)

{ super(id); <-- bool is used in this call this.bool = bool; <-- but not assigned until this call }

public getLoadingComponent(String id) {
if (bool)

{ return componentA; }

else

{ return componentB; }

}
}

---

Since getLoadingComponent(String) is called as part of the super constructor then the actual value of 'bool' can never be used. Furthur, if bool were an object instead of a primitive could potentially cause an NPE. Instead the loading component can be created in onBeforeRender():

protected void onBeforeRender() {
if (!renderedOnce)

{ loadingComponent = getLoadingComponent("content"); add(loadingComponent.setRenderBodyOnly(true)); renderedOnce = true; }

super.onBeforeRender();
}

... this also requires a change to the ajax behavior:

public boolean isEnabled(Component<?> component) {
return get("content") == loadingComponent || loadingComponent == null;
}