尝试编辑时，Rails form_for 结果是 POST 而不是 PUT

我在用Rails 4并出现以下错误。

路由错误
没有路线匹配 [POST] "/logs/1/meals/13/edit

我使用 :meal 传递模型对象的 form_ ，并且编辑页面正确呈现。然而，Rails 似乎并没有检查膳食对象是否已经保存，因此它不断尝试将表单发送到 #create 操作，并尝试发出 POST 请求，而不是将表单发送到更新操作并进行当我点击提交时发出 PUT 请求。

如何让 form_for 识别出我正在尝试更新现有对象并且需要 PUT 而不是 POST？其他一切都正常，我已经运行了所有迁移。我对 Rails 还很陌生，我几乎花了一整天的时间试图自己解决这个问题。请帮忙！

需要注意的是，当我尝试将模型对象作为 @meal.log 而不是 :meal 传递时，Rails 不再能够识别 :calorie_estimate 或 :meal_description。将模型对象作为 @meal.log 传递给我留下了无方法错误。

膳食/edit.html.erb

<h3> EDIT MEAL </h3>
<%= form_for(:meal) do |f| %>
<div id="meal-form">
    <%= f.text_field :calorie_estimate, class: 'meal-form-fields', :placeholder => "Calorie Estimate" %>
    <%= f.text_field :meal_description, class: 'meal-form-fields', :placeholder => "Food Description" %>
  <div class="submit-form" style="width: 75px; height: 15px;">
    <%= f.submit 'UPDATE', :class => 'submit-form-text' %>
  </div>
</div>
<% end %>

餐食控制器.rb

class MealsController < ApplicationController
  include MealsHelper

  def create
    @meal = Meal.new(meal_params)
    @meal.log_id = params[:log_id]
    @meal.save

    redirect_to log_path(@meal.log)
  end

  def edit
    @meal = Meal.find(params[:id])
  end

  def update
    @meal = Meal.find(params[:id])
    @meal.update(meal_params)
    redirect_to log_path(@log)
  end

  def meal_params
    params.require(:meal).permit(:calorie_estimate, :meal_description)
  end

end

可能的路线：

Prefix Verb   URI Pattern                            Controller#Action
         root GET    /                                      logs#index
    log_meals GET    /logs/:log_id/meals(.:format)          meals#index
              POST   /logs/:log_id/meals(.:format)          meals#create
 new_log_meal GET    /logs/:log_id/meals/new(.:format)      meals#new
edit_log_meal GET    /logs/:log_id/meals/:id/edit(.:format) meals#edit
     log_meal GET    /logs/:log_id/meals/:id(.:format)      meals#show
              PATCH  /logs/:log_id/meals/:id(.:format)      meals#update
              PUT    /logs/:log_id/meals/:id(.:format)      meals#update
              DELETE /logs/:log_id/meals/:id(.:format)      meals#destroy
         logs GET    /logs(.:format)                        logs#index
              POST   /logs(.:format)                        logs#create
      new_log GET    /logs/new(.:format)                    logs#new
     edit_log GET    /logs/:id/edit(.:format)               logs#edit
          log GET    /logs/:id(.:format)                    logs#show
              PATCH  /logs/:id(.:format)                    logs#update
              PUT    /logs/:id(.:format)                    logs#update
              DELETE /logs/:id(.:format)                    logs#destroy

路线.rb

Rails.application.routes.draw do

  root to: 'logs#index'

  resources :logs do
    resources :meals
  end
end

模式.rb

ActiveRecord::Schema.define(version: 20160128205351) do

  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

  create_table "logs", force: :cascade do |t|
    t.string   "entry_date"
    t.integer  "calorie_goal"
    t.string   "notes"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "meals", force: :cascade do |t|
    t.integer  "calorie_estimate"
    t.string   "meal_description"
    t.integer  "log_id"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

end

问题是你正在使用nested resources http://guides.rubyonrails.org/routing.html#nested-resources，因此你对哪个感到困惑@objects传递给你的form_for.

#app/views/meals/edit.html.erb
<%= form_for [@log, @meal] do |f| %>

正如你现在所拥有的那样，passing :meal含糊不清- Rails 无法识别将其提交发送到的路线/方法，因为它没有可用的数据。

如果你想update一个对象，您必须将适当的数据传递给表单，包括物体的id:

<%= form_for :meal, url: { controller: "meals", action: "update", id: "5" }, method: :put do |f| %>

比如 Rails 是面向对象 https://en.wikipedia.org/wiki/Object-oriented_programming，你最好将实际对象传递给你的form_for:

<%= form_for @meal ...

--

您遇到的问题是您有一个嵌套资源：

resources :logs do
  resources :meals #-> url.com/logs/:log_id/meals/:id
end

这意味着你需要通过Log and Meal http://apidock.com/rails/ActionView/Helpers/FormHelper/form_for#53-Nested-resources-in-form-for对你的价值观form:

#app/controllers/meals_controller.rb
class MealsController < ApplicationController
  def edit
     @log  = Log.find params[:log_id]
     @meal = Meal.find params[:id]
  end

  def update
     @log  = Log.find params[:log_id]
     @meal = Meal.find params[:id]   
     @meal.update meal_params     
  end
end

#app/views/meals/edit.html.erb
<%= form_for [@log, @meal] do |f| %>