对 rails 如何找到当前控制器中没有的动作感到困惑？

Question

This might be a dumb question, please forgive me. I am new to Rails and I google how to locate the actions that not included in current controller but could not figure it out. I noticed that Rails follows the inheritance characteristic. I am confused about how rails finds the 'log_in' method in create action? Since I did not include log_in action in current user controller and neither in user_helper controller and application_helper controller, rails should not find this action at all. Is there any convention that rails will find action in other places?

1.This is normal my user_controller.rb

class UsersController < ApplicationController
  before_action :set_user, only: [:show, :edit, :update, :destroy]
  before_action :require_login, except:[:new, :create] 

  # GET /users
  # GET /users.json
  def index
    @users = User.all
  end

  # GET /users/1
  # GET /users/1.json
  def show
    @user = current_user
  end

  # GET /users/new
  def new
    @user = User.new
  end

  # GET /users/1/edit
  def edit
  end

  # POST /users
  # POST /users.json
  def create
    @user = User.new(user_params)

    respond_to do |format|
      if @user.save
        log_in(@user)
        puts @user
        puts session[:user_id]

        format.html { redirect_to @user, notice: 'User was successfully created.' }
        format.json { render :show, status: :created, location: @user }
      else
        format.html { render :new }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end

2. This is my application_helper.rb

module ApplicationHelper
end

3. This is my users_helper.rb

module UsersHelper
end

4. This is my application_controller.rb

class ApplicationController < ActionController::Base
    before_action :require_login
        def require_login
            if !logged_in?
                redirect_to login_path
            end
        end
end

Answer 1

If this is a variant of the RailsTutorial, which it looks like from here , I think the log_in method is defined in a helper named SessionsHelper in app/helpers/sessions_helper.rb that looks something like this:

module SessionsHelper

  # Logs in the given user
  def log_in(user)
    session[:user_id] = user.id
  end
end

Helpers are automatically included into controllers, and public methods in helpers are available to both the controller and the view.