Ruby on Rails (3)
Demo5::Application.routes.draw do resources :students # The priority is based upon order of creation: first created -> highest priority. # See how all your routes lay out with "rake routes". # You can have the root of your site routed with "root" # root 'welcome#index' # Example of regular route: # get 'products/:id' => 'catalog#view' # Example of named route that can be invoked with purchase_url(id: product.id) # get 'products/:id/purchase' => 'catalog#purchase', as: :purchase # Example resource route (maps HTTP verbs to controller actions automatically): # resources :products # Example resource route with options: # resources :products do # member do # get 'short' # post 'toggle' # end # # collection do # get 'sold' # end # end # Example resource route with sub-resources: # resources :products do # resources :comments, :sales # resource :seller # end # Example resource route with more complex sub-resources: # resources :products do # resources :comments # resources :sales do # get 'recent', on: :collection # end # end # Example resource route with concerns: # concern :toggleable do # post 'toggle' # end # resources :posts, concerns: :toggleable # resources :photos, concerns: :toggleable # Example resource route within a namespace: # namespace :admin do # # Directs /admin/products/* to Admin::ProductsController # # (app/controllers/admin/products_controller.rb) # resources :products # endend
貌似只给我加了一个resources :students，这个路由它会去找哪个controller，从而响应那个view呢，恩，这是个问题，去看源码去，找controllers目录下有个students_controller，很显然这个请求交给这个controller处理了，Demo5/app/controllers/students_controller.rb，恩，就是他，代码是这样的
class StudentsController < ApplicationController before_action :set_student, only: [:show, :edit, :update, :destroy] # GET /students # GET /students.json def index @students = Student.all end # GET /students/1 # GET /students/1.json def show end # GET /students/new def new @student = Student.new end # GET /students/1/edit def edit end # POST /students # POST /students.json def create @student = Student.new(student_params) respond_to do |format| if @student.save format.html { redirect_to @student, notice: 'Student was successfully created.' } format.json { render action: 'show', status: :created, location: @student } else format.html { render action: 'new' } format.json { render json: @student.errors, status: :unprocessable_entity } end end end # PATCH/PUT /students/1 # PATCH/PUT /students/1.json def update respond_to do |format| if @student.update(student_params) format.html { redirect_to @student, notice: 'Student was successfully updated.' } format.json { head :no_content } else format.html { render action: 'edit' } format.json { render json: @student.errors, status: :unprocessable_entity } end end end # DELETE /students/1 # DELETE /students/1.json def destroy @student.destroy respond_to do |format| format.html { redirect_to students_url } format.json { head :no_content } end end private # Use callbacks to share common setup or constraints between actions. def set_student @student = Student.find(params[:id]) end # Never trust parameters from the scary internet, only allow the white list through. def student_params params.require(:student).permit(:name, :sex, :age, :phone) endend?
看到这句
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# GET /students # GET /students.json def index @students = Student.all end
这不就是得到/students请求并作处理的一个action吗，恩，是的，这个action名字叫index，在这里定义一个变量students并初始化，我的理解Student.all是执行了一个查询的请求，把数据库students表中的数据组装成一个个的对象存在变量students里，这里students应该相当于java中的list或是map类型的吧（会是数组吗？）。总之呢，这个controller定义了一个action，用于页面跳转的，一个变量students用于存储数据的，恩，就是这样，好了，请求到这里，下面初始化好students，页面应该跳转到index页面了吧，去看看index里都有什么，Demo5/app/views/students/index.html.erb，这个文件是一个嵌入了ruby代码的html，看看去。
<h1>Listing students</h1><table> <thead> <tr> <th>Name</th> <th>Sex</th> <th>Age</th> <th>Phone</th> <th></th> <th></th> <th></th> </tr> </thead> <tbody> <% @students.each do |student| %> <tr> <td><%= student.name %></td> <td><%= student.sex %></td> <td><%= student.age %></td> <td><%= student.phone %></td> <td><%= link_to 'Show', student %></td> <td><%= link_to 'Edit', edit_student_path(student) %></td> <td><%= link_to 'Destroy', student, method: :delete, data: { confirm: 'Are you sure?' } %></td> </tr> <% end %> </tbody></table><br><%= link_to 'New Student', new_student_path %>?
看这代码得配合着图片才有效果
相信很多人都能看懂代码啥意思了，其实细节地方我也不太懂，不过不影响咱理解他的大概意思。我们看到这个页面对数据有四种操作，增删改查，每个操作具体的交给那个action大家都明白吧，写的还是挺清楚的。下面咱就跟着链接走一遭吧，鼠标放到New Student上 ,我们看到浏览器左下角链接为localhost:3000/students/new，那就是要交给new这个action处理了，在students_controller里找到
# GET /students/new def new @student = Student.new end
恩，就是你了。在这里我就要说一下了，每个action都有一个相对应的xxx.html.erb，就是这个action将要跳转的页面。这里就是定义一个new的action和定义一个student的变量（应该说是对象吗，不太懂）并初始化（相当于java中的Student student = new Studen()吧），接下来就跳转到new.html.erb页面了，咱也跟着走。
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看看代码去Demo5/app/views/students/new.html.erb
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<h1>New student</h1><%= render 'form' %><%= link_to 'Back', students_path %>
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这么简单，from就能生成一个表单吗，这个表单在哪呢，恩？view目录下有个视图文件_form.html.erb，去看看
<%= form_for(@student) do |f| %> <% if @student.errors.any? %> <div id="error_explanation"> <h2><%= pluralize(@student.errors.count, "error") %> prohibited this student from being saved:</h2> <ul> <% @student.errors.full_messages.each do |msg| %> <li><%= msg %></li> <% end %> </ul> </div> <% end %> <div name="code"> # POST /students # POST /students.json def create @student = Student.new(student_params) respond_to do |format| if @student.save format.html { redirect_to @student, notice: 'Student was successfully created.' } format.json { render action: 'show', status: :created, location: @student } else format.html { render action: 'new' } format.json { render json: @student.errors, status: :unprocessable_entity } end end end?
拿到表单传过来的参数，初始化student，student_params是什么？传过来的参数？怎么接收的呢？看students_controller.rb
private # Use callbacks to share common setup or constraints between actions. def set_student @student = Student.find(params[:id]) end # Never trust parameters from the scary internet, only allow the white list through. def student_params params.require(:student).permit(:name, :sex, :age, :phone) end
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这个应该相当于java中的set,get方法吧（我是这么理解的，我想应该差不多），set_student是设置student对象的，应该是初始化，注意是通过参数中的id初始化的，从这里我们想到，当我们把鼠标放到链接地址上是，url通常是localhost:3000/students/1或者是localhost:3000/students/1/edit等等，这里的1、2、3。。。应该是student的id,这样才能知道是在操作哪个student，set_student通过id从数据库中找到相应的student数据把他组装成对象（是对象吧，暂时这么理解）赋值给@studnet,@是定义变量用的。注意在students_controller开头的地方有一句
before_action :set_student, only: [:show, :edit, :update, :destroy]
这句话就是说在执行show,edit,update,destroy这些action之前先给我把student对象初始化好，这就是set_studnet存在的意义。
至于student_params的作用就不多说了吧，就像我create student，提交过来的是一个表单信息，我肯定是通过studnet_params把表单里的数据和对象里的字段对应起来，这样才能组装成一个student对象存到数据库中。
我们看到create的action定义里有一个if-else语句，这个就是说create成功我就跳到show的action里，不成功返回到new的action并带回错误信息。
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2.show
其实show这个请求还是比较简单的，就是通过url请求，到达show的action，我们看到show的action的url为localhost:3000/students/1 这样就把要show那个student定义好了，前面说过了，在show之前要先执行set_student，就是通过url传过来的id从数据库中取得相应的student数据初始化好对象student，这样就能把初始化好的studnet传到view页面进行渲染了。恩，就是这样。
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3.edit
edit和show差不过，就是多了一步update操作，我们看下update的action定义
# PATCH/PUT /students/1 # PATCH/PUT /students/1.json def update respond_to do |format| if @student.update(student_params) format.html { redirect_to @student, notice: 'Student was successfully updated.' } format.json { head :no_content } else format.html { render action: 'edit' } format.json { render json: @student.errors, status: :unprocessable_entity } end end end?
if语句是对update操作成功或是失败的处理。成功就重定向到show的页面，失败就跳到edit的action里，并带回错误信息。
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4.destroy
<td><%= link_to 'Destroy', student, method: :delete, data: { confirm: 'Are you sure?' } %></td>相信大家都懂得，没啥东西，看action
# DELETE /students/1 # DELETE /students/1.json def destroy @student.destroy respond_to do |format| format.html { redirect_to students_url } format.json { head :no_content } end end?
@student.destroy是调用destroy方法将数据库中对应的数据删除。成功后重定向到index的action里。
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到这里，CRUD差不多解释完了，下面该干啥了，目标：
使用devise实现用户的注册、登录、找回密码以及修改密码。找回密码会涉及到mail配置以及发送
点击下载源码： Demo5源码