Rails：NoMethodError未定义的方法

Question

I'm trying to build a basic Rails/React app which takes in a series of user inputs, then displays them on the screen within a letter template (think MadLibs.) I've followed several React tutorials and I have a decent amount of experience with Rails but I've gotten amazingly hung up with an API I've created. For context I'm using this tutorial here as a guide, but am building my own app.

This is my routes file:

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

  namespace :api do
    namespace :v1 do
      resources :letters, only: [:index, :create]
    end
  end
end

This is my base_controller.rb file:

class Api::V1::BaseController < ApplicationController
    respond_to :json
end

and this is my letters_controller.rb file:

class Api::V1::LettersController < Api::V1::BaseController
    def index
        respond_with Letter.all
    end

    def create
        respond_with :api, :v1, Letter.create(letter_params)
    end

    private
        def letter_params
            params.require(:letter).permit(:id, :param_one, :param_two)
        end
end

The controller files are both stored in controllers/api/v1 and this is reflected in my routes file. I'm able to use the index method no problem and get all Letter objects to display. I'm able to use the create method somewhat, in that a new Letter is created and saved to the database (sqlite btw.) Problem comes with the response, as in there isn't one. Instead of a response coming back to my AJAX call I'm getting the following:

NoMethodError (undefined method `api_v1_letter_url' for #<Api::V1::LettersController:0x007f3085f1d300>):
  app/controllers/api/v1/letters_controller.rb:7:in `create'

I have no earthy idea why this isn't working. From everything that I've read feeding the respond_with call the parameters I have should cause the returned url to work and come back with a response. Instead I get this strange 500.

I've never had so much trouble with a program that it's given me a migraine before. If anyone can help it will be greatly appreciated.

Answer 1

If you run rake routes , you will see that there is no declaration for api_v1_letter_url .

This is because you do not declare a show method on routes.rb (you explicitly only use index and create ). If you want the call in your controller to work as-is, you need a show method:

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

  namespace :api do
    namespace :v1 do
      resources :letters, only: [:index, :create, :show]
    end
  end
end

Now, run rake routes , you'll see it's there.

To implement show in your controller:

def show
  respond_with Letter.find(params[:id])
end