Visualforce Developer Guide
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Deferred Creation of Dynamic Components
The Apex method that defines a dynamic component is by default executed at page load
time, before any action method that’s defined for the page is run. Set the invokeAfterAction attribute of a dynamic component to
true to wait for page actions to be completed
before the method that creates the dynamic component runs. This enables you to design
dynamic components that change depending on the result of, for example, a page
initialization action or a callout.
Here’s a page that has a single dynamic component, which is created after the
page’s action method, pageActionUpdateMessage, is
completed.
<apex:page controller="DeferredDynamicComponentController"
action="{!pageActionUpdateMessage}" showHeader="false">
<apex:dynamicComponent componentValue="{!dynamicComp}" invokeAfterAction="true"/>
</apex:page>Here’s the associated controller that provides the dynamic component definition,
and illustrates the effect of the invokeAfterAction
attribute.
public class DeferredDynamicComponentController {
private String msgText { get; set; }
public DeferredDynamicComponentController() {
this.msgText = 'The controller is constructed.';
}
public Component.Apex.OutputPanel getDynamicComp() {
// This is the component to return
Component.Apex.OutputPanel dynOutPanel= new Component.Apex.OutputPanel();
dynOutPanel.layout = 'block';
// Child component to hold the message text
Component.Apex.OutputText msgOutput = new Component.Apex.OutputText();
msgOutput.value = this.msgText;
dynOutPanel.childComponents.add(msgOutput);
return dynOutPanel;
}
public Object pageActionUpdateMessage() {
this.msgText= 'The page action method has been run.';
return null;
}
}Deferred Creation of Dynamic Components and Other Actions
invokeAfterAction="true" affects dynamic
components immediately at page load time, because that’s when page actions
run. Setting invokeAfterAction="true"
reverses the order of component creation and any action method on the page.
That is, the order of execution is changed for action methods on all of the following components.
- <apex:actionFunction>
- <apex:actionPoller>
- <apex:actionSupport>
- <apex:commandButton>
- <apex:commandLink>
- <apex:page>
When invokeAfterAction="false" is set on a
dynamic component, the order of execution is as follows. This is the default
behavior for dynamic components.
- Invoke the dynamic component’s creation method, which constructs the component.
- Invoke the action method.
- Rerender the page.
When invokeAfterAction="true" is set on a
dynamic component, the order of execution is as follows.
- Invoke the action method.
- Invoke the dynamic component’s creation method, which constructs the component.
- Rerender the page.