Unable to pass a parameter <apex:param> to a relevant method

Question

Lets assume I have a Page code:

<apex:pageBlockTable value="{!allContacts}" var="c" >
            <apex:column value="{!c.id}" headervalue="ID"/>
            <apex:column value="{!c.FirstName}" headervalue="First Name"/>
            <apex:column value="{!c.LastName}" headervalue="Last Name"/>
            <apex:column value="{!c.Title}" headervalue="Title"/>
            <apex:column value="{!c.Company}" headervalue="Company"/>
            <apex:column>
                <apex:commandButton action="{!addToRecruits}" value="Recruit">
                    <apex:param assignTo="{!leadID}" name="leadID" value="{!c.id}"/>
                </apex:commandButton>
            </apex:column>
</apex:pageBlockTable>

And relevant controller :

    public String leadID { get; set; }

    public PageReference addToRecruits() {
        System.debug('LeadID is: ' + leadID);
        List<Lead> potentialCandidate = [SELECT id, FirstName, lastName, Title, Company FROM Lead WHERE id = :leadID];   
        delete potentialCandidate;

        return null;
    }

It seems that I can NOT pass leadID to addToRecruits() method. Do you have any idea why is so?

UPDATE:

I could manage to solve it. Instead of querying using SOQL, I approached with this style:

public String leadID { get; set; }
public PageReference addToRecruits() {

    Lead candidate=new Lead(id=leadID);
    ....
}

Answer 1

There's a long outstanding defect with passing parameters from an apex:commandButton. A hack to get around the defect is to set the rerender attribute on the apex:commandButton element. See Bob Buzzard's blog: http://bobbuzzard.blogspot.com/2011/07/passing-parameters-to-apex-method-from.html

Answer 2

It's a "known bug" by the dev community but it never made to the list...

Jeff Douglas has written this up together with viable workarounds in March 2010: http://blog.jeffdouglas.com/2010/03/04/passing-parameters-with-a-commandbutton/ (the post and comments also contain few useful links to SF message boards).