是否可以将Rails的值返回给客户端JavaScript？

Question

I am working on a move from a Python back end to Ruby on Rails, and some of the legacy client-side js code looks like this:

$http.post(url, data, config).
    success(function(data, status, headers, config) {
        if(data == 0) {
            $scope.subscribed = 'true'
        } else {
            alert("There is an issue with that email address.")
            return
        }
    }).
        error(function(data, status, headers, config) {
        return
    });

I now have the back-end doing what it is supposed to do here, but unless I use the flash, I'm not sure how to return the success/failure status to the calling function. I'd like to just return an integer value so the code could continue to work as is. Is that possible? Or do I need to rewrite the front-end to use the flash hash?

EDIT: For the record, this is what the backend code that handles this looks like.

Routes:

Rails.application.routes.draw do
  root to: 'static_pages#index'

  resources :subscriptions, only: [:create]

  match '/subscribe', to: 'subscriptions#subscribe', via: :post

end

The controller:

class SubscriptionsController < ApplicationController
  protect_from_forgery
  returnVal = -1

  def subscribe  
    begin
      # Do some stuff that could cause an exception>
      flash[:success] = "Subscribed successfully"
      logger.debug flash[:success]
      returnVal = 0
    rescue <Some exception>
      flash[:error] = "Error"
    rescue <Another exception>
      flash[:error] = "Error"
    end

    if (!flash[:error].blank?)
      logger.debug flash[:error]
    end

    render 'static_pages/index'
    return returnVal
  end
end

All seems to be working fine except for the "return" part.

Answer 1

In Rails controllers, you don't return the text you want to send to the browser. Instead, you render it.

For example:

render plain: returnVal

(From the Rails Guide on layouts and rendering )

Also, you probably don't need the flash hash. flash is for temporarily storing session data and retrieving it in the next request. Since you're only making one request here, flash is unnecessary.

Or do I need to rewrite the front-end to use the flash hash?

The front-end can't use the flash hash. That's only accessible on the server.

I'm not sure how to return the success/failure status to the calling function.

Your use of phrases like this makes me wonder if you really understand what's going on here. You can't directly call sever-side functions from the client. All you can do is make HTTP requests, just like the browser does when it visits a page. Your code just tells the browser to download a page, and the Rails backend renders the response inside that page, just like it would with any other webpage you might visit.