How to display List<Schema.Childrelationship> records in pageblocktable

Question

controller

public class objectLists{
    public String SeletedObject {get; set;}
    public  String childObj {get;set;}
    List<SelectOption> options;

    public List<SelectOption> getObjectOptions() 
    {
         options = new List<SelectOption>();
         Map<String, Schema.SObjectType> AllObjmap   = New Map<String, Schema.SObjectType>();
         AllObjmap = Schema.getGlobalDescribe();

         System.debug('******All object Names******* :'+ AllObjmap.keyset());

         for(String ObjectName: AllObjmap.keySet())
         {
            List<string> objlist = new List<string>();
            objlist.add(ObjectName);
            options.add(new SelectOption(ObjectName,ObjectName));

        }
        return options;        
    }
    public void getrelatedchild()
    {
         Map<string,string> childMap = new Map<String, String>();
         List<Schema.Childrelationship> childList = Schema.getGlobalDescribe().get(SeletedObject).getdescribe().getChildRelationships();
    }
}

vf page

<apex:page controller="objectLists" >
    <apex:form >
        <apex:pageBlock title="Select Object">

           <apex:actionFunction name="getchild" action="{!getrelatedchild}" oncomplete="alert('compeleted')" />

            <apex:outputPanel >Object:</apex:outputPanel>

              <apex:selectList size="1" value="{!SeletedObject}" onchange="callchild();">
                    <apex:selectOptions value="{!ObjectOptions}" />
              </apex:selectList> 

           <apex:pageBlockTable value="{!childObj}" columns="2" var="item" id="a">

           </apex:pageBlockTable>

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

I'm creating picklist of Standard and custom objects, after selecting specific object I want to display related records to that object in pageblocktable. I'm able to add the objects in picklist but unable to disply related records in pageblocktable

Answer 1

You certainly can't specify a return type of void. Just return the List<ChildRelationship> and be done with the Apex involved. Here's a demo with just the ChildRelationship table:

Controller

public with sharing class Demo
{
    public List<ChildRelationship> getRelationships()
    {
        return SObjectType.MyObject__c.getChildRelationships();
    }
}

Page

<apex:page controller="Demo">
    <apex:pageBlock>
        <apex:pageBlockTable value="{!relationships}" var="relation">
            <apex:column value="{!relation.childSObject}" />
            <apex:column value="{!relation.field}" />
            <apex:column value="{!relation.relationshipName}" />
        </apex:pageBlockTable>
    </apex:pageBlock>
</apex:page>

Interestingly, it seems like you ought to be able to use {!$ObjectType.MyObject__c.childRelationships} where I have {!relationships} and get rid of Apex altogether, but it does not seem to be supported.