Workaround for ApexPages.currentPage() in schedulable class

Question

A visualforce page controller uses ApexPages.currentPage().getParameters().get('id'); in its constructor.

I need to call this controller from apex schedulable class. So before creating instance i set page parameter as:

ApexPages.currentPage().getParameters().put('id',this.sid); but this is not working in schedulable class but this approach works in test class (therefore i used it in schedulable class).

//Code reference in schedulable
public void execute(SchedulableContext ctx)
{
    ApexPages.currentPage().getParameters().put('id',this.sid); // Exception: Attempt reference null        
    MyController con = new MyController();
}

Is there any workaround or need to change approach? Just want to know possibilities.

Answer 1

Fairly certain you'll need to change your approach. Fortunately this can be a quick refactor. Just extract your constructor into a method that takes the id param, then create a second constructor that also takes and id param, and wire it all up. You'll then be able to call it from your batch class without having to deal with re-testing the visualforce controller you tweaked.

Initial Constructor

public class MyController {
    private Id myId;

    public MyController() {
        myId = ApexPages.getCurrentPage().getParameters().get('id');
        ... stuff you don't want to touch ...
    }
}

Refactored

public MyController {
    private Id myId;

    public MyController() {
        init(ApexPages.getCurrentPage().getParameters());
    }

    public MyController(Id fromTestId) {
        init(fromTestId);
    }

    private void init(Id inputId) {
        myId = inputId;
        ... stuff you don't want to touch ...
    }
}

Answer 2

Just gave +1 for @Sdry's comment on this question.

While these answers technically resolve this particular problem, if your code base is growing in complexity you may want to start to think more about a better Separation of Concerns and layering of your logic to avoid problems like this when reusing code between different contexts.

Following a Service layer (part of the above series) approach encapsulates logic in way that is agnostic of the caller and thus does not make assumptions such as having ApexPages in scope.

Obviously as is the nature of software development we don't always get this option to refactor existing code bases, hence the immediate need I'm glad has been resolved. Sometimes we can do things incrementally just by starting a MyXYZService class and agreeing a few rules on what code can and cannot do it it and encouraging through incremental development to converge into it.

Hopefully some food for thought... :-)

Answer 3

How is the scheduled class called? Does your VF page schedule the class? For example (and correct me if I am wrong), is it like you have a VF page with a standard controller on, say, Account. And then you want the VF page to schedule the class to do something neat pertaining to the specific Account we're viewing on the VF page. If this is the case you could try the following:

You'd need to collect the id of the record you're concerned with and pass that to the scheduled class. Then in the scheduled class, you need to create a new instance of your VF controller class, but to do this, you'll need to pass it an ApexPages.StandardController for the id that gave the scheduled class. "Cool," you may say, "but what about the error in calling ApexPages.currentPage().getParamters()?" To overcome this obstacle (assuming you are using a standard controller), just use the getId method of the ApexPages.StandardController class.

Now, if you're not using a standard controller, (and even if you are) you can always create multiple initialization methods for your VF controller.

For example:

public class myVFController{

    private id acctId;

    // to be used as a controller for a VF page 
    public myVFController(){
        acctId = ApexPages.CurrentPage().getParameters().get('id');
    }

    // so myVFController can be used as an extension for StandardController
    public myVFController(ApexPages.StandardController con){ 
        acctID = con.getId();
    }

    // to be used in your scheduled code
    public myVFController(id acctId){
        this.acctId = acctId;
    }

}  

And then in your scheduled class, make sure you initialize your VF controller by passing calling:

myVFController con = new myVFController(myAcctId);