Can you access parent object fields in a 'New' page override without using SOQL?

Question

I have two objects, Parent__c and Child__c, Child__c has a lookup field to Parent__c calledParentId__c.

I have overridden the New and Edit pages for Child__c using a Visualforce page with the Child__c standard controller.

<apex:page standardController="Child__c" extension="ParentChildExtension">
    <apex:sectionHeader title="{!Child__c.ParentId**r.Name}"/>
</apex:page>

If I click the Edit button on the Child__c related list to access my page, the apex:sectionHeader title is populated. However when I use the New button it is not.

I've tried using the addFields method in my controller to add the Name (and other fields) from Parent__c that I'm interested in but this still does not work when using the New button.

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Edit Button Behaviour

Visualforce Page

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New Button Behaviour

Visualforce Page

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This is easily solved by querying for the Name field of Parent__c in a controller extension (if it's missing), but is there a way of doing this that without using a controller extension and/or a SOQL query (and preferably without resorting to the "lkid hack" mentioned in Keith C's answer)?

public with sharing class ParentChildExtension
{
    private final Child__c child;

    private String parentName;

    public ParentChildExtension(ApexPages.StandardController stdController)
    {
        this.child = (Child__c)stdController.getRecord();
        this.parentName = child.ParentId**r.Name;
    }

    public String getParentName()
    {
        if(parentName == null)
        {
            parentName = [SELECT Name FROM Parent__c WHERE Id = :child.ParentId__c].Name;
        }

        return parentName;
    }
}

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EDIT: Added stipulation that I would prefer to avoid the "lkid hack" if possible, and that I've tried using the addFields method in my controller.

Answer 1

The standard controller addFields method supports field access via relationship fields allowing you to pass the responsibility back to the standard controller to do the querying. But "New" behaving differently to "Edit" suggests that the problem may be more related to differences in how the standard controller handles the two situations. But addFields is worth a quick try.

Beyond that, you'll note some command-line parameters get automatically added that identify the id and name of the parent object. (Google "Lkid hack" for more detail.) As you don't care about the specific key values, you can just grab the id and name from there.

PS But as the comment thread below discusses, given the choice between an extra query and relying on Salesforce not changing the URL pattern, the extra query is the way to go. Meanwhile, a load more votes and comments on https://success.salesforce.com/ideaView?id=08730000000gM7mAAE for the benefit of future generations can't do any harm.