Error Handling in Rails

Rails makes error handling pretty easy.

In my WoW Quest lookup application, I pass a user inputted numeric to a API call.  I would get back a JSON result and then post the result to the results.html.erb page that the user would be routed to. 

It was fine, except that if a user inputs a numeric that doesn't map to a valid quest, the user would get a broken page. 

So here's what I did.  I found that if you send an invalid Quest ID to WoW's API, it returns this JSON:

{"status":"nok", "reason": "unable to get quest information."}

So in the controller, I made a modification on the Results action.  I added something called "rescue."

Rescue handles errors in Rails. 

So now, my results action looks like this, with the added bit in Red text below: 

  def results

   @output = JSON.parse(open("http://us.battle.net/api/wow/quest/"+params[:qid]).read)
  rescue
    render :template => 'search/error', :status => "nok"
  end 

Basically it's saying this:

If the JSON comes back with a element called "status" and it's equal to the string "nok", then redirect to "view/search/error.html.erb"

That's it.  Now if a user inputs a invalid quest id, like 667, it will go to my error.html.erb page... which has some HTML in it to basically say you hit an error, and put a link to go back.