Difficulty with apex:param and apex:actionsupport

Question

Trouble with Action Support

---

Currently, I have been very successful with my page until I ran into a snag with my action:support tag.

I simply need to collect an Id, collected on the a form, then based on that Id, alter a Boolean for rendering purposes.

However, the value being bound is not being set or captured. Even more odd is that when I set immediate to true, the Id parameter called PossibleWhoId is being populated with a null value. As for if it is false, it doesn't even show up in ViewState.

Needless to say, there is a slight anomaly here.

The VisualForce Code

...
<apex:pageBlockSection>
<apex:inputField value="{!Task[TaskField]}" required="{!TaskField.Required}" id="Who">
    <apex:actionSupport event="onchange" reRender="TaskPageBlockButtons" id="Name" action="{!DisableOrEnableAddOfficeContactButton}" immediate="true">
        <apex:param name="PossibleWho" assignTo="{!PossibleWhoId}" value="{!Task[TaskField]}"/>
    </apex:actionSupport>
</apex:inputField>
</apex:pageBlockSection>
...

The Apex Code

public Id PossibleWhoId { get; set; }
public PageReference DisableOrEnableAddOfficeContactButton()
{
    this.IsNotPrimaryContact = this.CurrentTask.WhoId == null 
        ||  this.CurrentTask.WhoId.getsObjectType().getDescribe().getName() != 'Contact'; 
    return null;
}

Answer 1

Okay, after some guidance from eyescream, I came up with the following:

Using a suggestion found on this developerforce article and some off the wall advice. I came up with a decent but hacky solution.

Using the document.getElementById function, I was able to pass parameters like so:

In VisualForce

<apex:inputField value="{!Task[TaskField]}" required="{!TaskField.Required}" id="Who"
onchange="AssignNewWhoId((document.getElementById('{!$Component.Who}' + '_lkid')).value)"/>

I then, took advantage of this via an apex:actionfunction:

More VisualForce

<apex:actionFunction name="AssignNewWhoId" action="{!DisableOrEnableAddOfficeContactButton}" reRender="AddOfficeContactButtonTop, AddOfficeContactButtonBottom" immediate="true">
    <apex:param value="" name="NewWhoId"/>
</apex:actionFunction>

Now that I was able to do that. I simply assigned the collected Id within my DisableOrEnableAddOfficeContactButton method:

this.CurrentTask.WhoId = Apexpages.currentPage().getParameters().get('NewWhoId');

That's all she wrote.