Question

I am trying to develop a visualforce custom component which takes an attribute from a visual force page. I need to access that attribute in controller’s Constructor so that i can brings some records from database and i need to display those records in the Component. But problem is that i am not getting Attribute value in Controller.

See the below code to understand the problem clearly..

Controller :

public with sharing class AdditionalQuestionController {
    public String CRFType {get;set;}
    public AdditionalQuestionController () {
        system.debug('CRFType : '+CRFType);
        List<AdditoinalQuestion__c> lstAddQues = [Select AddQues__c from AdditoinalQuestion__c wehre CRFType = :CRFType];
        system.debug('lstAddQue : '+lstAddQue);
    }
}

Component :

<apex:component controller="AdditionalQuestionController" allowDML="true">
    <apex:attribute name="CRFType" description="This is CRF Type."  type="String" required="true" assignTo="{!CRFType}" />
        <apex:repeat value="{!lstAddQue}" var="que">
            {!que}<br />
        </apex:repeat>
</apex:component>

VisualForce page :

 <apex:page >
    <c:AdditionalQuestionComponent CRFType="STE" />
</apex:page>

Thanks,
Vivek

Answer 1

Setter methods on the attributes in a VF component appear to be called after the constructor has returned, unfortunately. Here’s an alternative solution for your controller that uses a getter method to populate your list (which would be called after your CRFType member variable has been set):

public with sharing class AdditionalQuestionController {
    public String CRFType {set;}
    public AdditionalQuestionController () {
        system.debug('CRFType : '+CRFType); // this will be null in the constructor
    }
    public List<AdditoinalQuestion__c> getLstAddQue() {
        system.debug('CRFType : '+CRFType); // this will now be set
        List<AdditoinalQuestion__c> lstAddQues = [Select AddQues__c from AdditoinalQuestion__c wehre CRFType = :CRFType];
        system.debug('lstAddQue : '+lstAddQue);
        return lstAddQue;
    }
}