Called once per request on components before they are about to be rendered. This method
should be used to configure such things as visibility and enabled flags.
Overrides must call super.onConfigure(), usually before any other code
NOTE: Component hierarchy should not be modified inside this method, instead it should be
done in Component.onBeforeRender()
NOTE: Why this method is preferrable to directly overriding Component.isVisible() and
Component.isEnabled()? Because those methods are called multiple times even for processing of
a single request. If they contain expensive logic they can slow down the response time of the
entire page. Further, overriding those methods directly on form components may lead to
inconsistent or unexpected state depending on when those methods are called in the form
processing workflow. It is a better practice to push changes to state rather than pull.
NOTE: If component's visibility or another property depends on another component you may call
other.configure() followed by other.isVisible() as mentioned in
Component.configure() javadoc.
NOTE: Why should Component.onBeforeRender() not be used for this? Because if visibility of a
component is toggled inside Component.onBeforeRender() another method needs to be overridden
to make sure Component.onBeforeRender() will be invoked on invisible components:
class MyComponent extends WebComponent
{
protected void onBeforeRender()
{
setVisible(Math.rand() > 0.5f);
super.onBeforeRender();
}
// if this override is forgotten, once invisible component will never become visible
protected boolean callOnBeforeRenderIfNotVisible()
{
return true;
}
}
VS
class MyComponent extends WebComponent
{
protected void onConfigure()
{
super.onConfigure();
setVisible(Math.rand() > 0.5f);
}
}
- Overrides:
onConfigure in class Component
org.apache.wicket.Component