Better error handling for ajax http request

[Xiaohong-Deng]

now we have two controller actions for ajax calls which in successful cases don't serve a html page back, just a html snippet for inserting or a state indicating success.

now the problem is if something wrong happens, what we can do to inform the user something is wrong? redirect_to is not going to work. I haven't tried render and I doubt that would be any better.

one is Answers#update

  def update
    authorize @answer
    if @answer.make_judge_identified!
      ActionCable.server.broadcast "game-#{@answer.question.game_id}: info", { message: "Judge made his choice", message_type: "info" }
      head :ok
    else
      # send from a remote call, so no redirect_to actually
      flash[:alert] = "Judge choice has not been updated."
      redirect_to root_path
    end
  end

note that if authorize @answer fails the error gets handled by a general purpose method, which uses redirect_to

the other is Games#judge

  def judge
    authorize @game
    render layout: false
  end

[Xiaohong-Deng]

In the happy path, we did broadcast info to users and return a 200 ok to the browser. We can use a javascript callback to do something with the 200 ok (ajax:success)

In the sad path, we might be able to use the oppsite info.