Salesforce VF Page: Retrieve Field without SOQL

I was working on a Salesforce project which involves a lot of VisualForce page customisation. During the development, I encountered a very common error “SObject row was retrieved via SOQL without querying the requested field”, but it took me awhile to find out the root cause.

I wrote a VisualForce with Standard Controller and an Extension class. Below is the code:

Extension Class:

public class myControllerExtension {

    public extendedobject__Extended_Object__c myObj {set; get;}

    public myControllerExtension(ApexPages.StandardController stdController) {
        this.myObj = (extendedobject__Extended_Object__c)stdController.getRecord();

    }
}

VisualForce Page:

As you can see that I only display the record Name in the VisualForce page, and I assumed that Salesforce will retrieve the value for me automatically according the Id that I passed in the url. However, this is not the case. After doing some research, I found two methods to solve this issue:

Option 1

Specify the list of fields that I want to retrieve and set it to the standardController

public myControllerExtension(ApexPages.StandardController stdController) {
        List fields = new List{'Name'};
        stdController.addFields(fields);

        this.myObj = (extendedobject__Extended_Object__c)stdController.getRecord();

}

Option 2

Change the variable in the VisualForce page to use the object name instead of the variable that I specified in the Extension class