String coming through as null after apex:param

Question

Hi I have a lookup field which returns an opportunity if available, currently once i select an opportunity an actionsupport is triggered onchange, I then want to put that value from the lookup field into the controller using an apex:param however when i debug it in the controller its coming through as blank

Visualforce

<apex:inputField value="{!pb.CXT_Opportunity_Name__c}"> 
      <apex:actionSupport event="onchange" action="{!checkIfSelectedContactHasPendingOpp}"  rerender="testing">
          <apex:param name="PendingOpportunityName" assignTo="{!PendingOpportunityName}" value="{!pb.CXT_Opportunity_Name__c}"/>
      </apex:actionSupport>
</apex:inputField>

controller

public string PendingOpportunityName {get;set;}

 public pagereference checkIfSelectedContactHasPendingOpp(){
    system.debug(PendingOpportunityName);

    return null;
}

the debug just returns empty, any help would be awesome, Thanks

Answer 1

If CXT_Opportunity_Name__c is a Lookup to another object, you're passing the object value to a String which wouldn't work.

What you'd need to do is assign the value to an instance of that object, then get the Name. For example:

Apex Class

public CXT_Pass_Registration__c PendingOpportunityName { // Change the variable to an instance of the object
    get;
    set;
}

public pagereference checkIfSelectedContactHasPendingOpp(){
    system.debug(PendingOpportunityName.Name); // Access the variable (object) and then, the Name
    return null;
}

public MyCustomController() {
    PendingOpportunityName = new CXT_Pass_Registration__c();
}

Visualforce Page

<apex:page controller="MyCustomController">
    <apex:inputField value="{!PendingOpportunityName.CXT_Opportunity_Name__c}" />
</apex:page>

Answer 2

You are missing rerender here. Add rerender in your actionsupport and also add in value in param

<apex:actionSupport event="onchange" action="{!checkIfSelectedContactHasPendingOpp}" rerender="none"> 
       <apex:param name="PendingOpportunityName" assignTo="{!PendingOpportunityName}" value="{!pb.CXT_Opportunity_Name__c}"/>    
</apex:actionSupport>