ApexPage.Action passed to VF component as component stays null and cannot be invoked

Question

I have a custom VF component that gets passed in an ApexPages.Action (=passedInAction()) that needs to be invoked when the user performs some changes inside the component (=doInvokeAction() method).

My problem is that the passed in action always is null when it's going to be invoked. What is that so?

Component markup:

<apex:component controller="ComponentCtrl" allowDML="true"> 
  <apex:attribute name="onAction" assignTo="{!passedInAction}" type="ApexPages.Action" required="false" description="" />
  <apex:attribute name="rerenderOnPage" type="String" required="false" description="" /> 

  ...
          <apex:inputCheckbox...>
              <apex:actionSupport event="onclick" action="{!doInvokeAction}" rerender="componentIds,{!rerenderOnPage}" />
          </apex:inputCheckbox>
  ...            
</apex:component>

Component controller:

public with sharing class ComponentCtrl {

  public ApexPages.Action passedInAction { get; set; }

  ...


    public PageReference doInvokeAction() {
        someInternalComponentsStuff()

        return passedInAction.invoke(); <--- NULLPOINTER HERE!
    }
}

VF Page using the component and passing in its Action:

<apex:page standardController="CustomObject__c" extensions="PageCtrlExt" recordSetVar="dlis" sidebar="false">

  ...
  <apex:form id="form">

        <c:myComponent onSelect="{!actionToPassIn}"
                       rerenderOnSelect="selectedItem" />   


  </apex:form> 
</apex:page>

VF Page Controller Extension:

public with sharing class PageCtrlExt {

  ...


    public PageReference actionToPassIn() {
        ....

        return null;
    }
}

Answer 1

This is an alternative strategy that should achieve the same goal.

1. Define an interface with one method
2. Implement the interface in the controller
3. Make the component parameter be type [the interface you defined]
4. Pass the controller into the component
5. Call the method on the passed in controller

Some minimal bits of code:

public interface ActionInterface {
  PageReference actionToInvoke()
}

public class PageCtrl implements ActionInterface {
  public PageReference actionToInvoke() {
   //do things
   return null;
  }
}

public class ComponentCtrl {
  public ActionInterface aif {get; set;}

  public PageReference invokeAction() {
    return aif.actionToInvoke();
  }
}

To get the PageCtrl reference into the ComponentCtrl, pass "this" in your VF page like this:

<c:myComponent actionInterfaceParamName="{!this}" />  

Answer 2

Create an actionFunction on component document.ready method and call the doInvokeAction() method in there. Don't know whether it is a salesforce issue but the values to the component always are reflected as null during the first page load