Ruby on Rails (3)
项目是生成好了，貌似自己还没写一句代码呢，rails把工作全给我做了，这就遇到个问题，他都给我配置了什么东西，我如果需要改一个地方的话，会不会对其他地方有影响从而发生错误呢，相信这是每一个新手都有的疑问，想到这就两眼一抹瞎，不知道怎么办了，怎么才能理清楚到底是怎么回事，我心想，那就看他代码去吧，看能不能把整个项目流程跟着代码走一遍，恩，说干咱就干。
1.new
首先我们通过url访问我们的项目，http://localhost:3000/students，这个请求到WEBrick服务器里它会怎么响应呢。不清楚啊，不过咱还是知道他最后是通过路由表找到相应的路径的，那咱就去路由表文件看看吧。Demo5/config/routes.rb
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
# end
end
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)
end
end
看到这句
# GET /students
# GET /students.json
def index
@students = Student.all
endListing students
Name
Sex
Age
Phone
<% @students.each do |student| %>
<%= student.name %>
<%= student.sex %>
<%= student.age %>
<%= student.phone %>
<%= link_to 'Show', student %>
<%= link_to 'Edit', edit_student_path(student) %>
<%= link_to 'Destroy', student, method: :delete, data: { confirm: 'Are you sure?' } %>
<% end %>
<%= 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 
看看代码去Demo5/app/views/students/new.html.erb
New student
<%= render 'form' %>
<%= link_to 'Back', students_path %>
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? %>
<%= pluralize(@student.errors.count, "error") %> prohibited this student from being saved:
<% @student.errors.full_messages.each do |msg| %>
- <%= msg %>
<% end %>
<% end %>
<%= f.label :name %>
<%= f.text_field :name %>
<%= f.label :sex %>
<%= f.text_field :sex %>
<%= f.label :age %>
<%= f.number_field :age %>
<%= f.label :phone %>
<%= f.text_field :phone %>
<%= f.submit %>
<% end %>
这个是根据我们model的字段生成的一个form，上面是错误处理，下面就是各个字段的展示了，最后是一个action按钮，用于提交表单的，跟html挺像的是吧，我们就不研究他了，这个表单可以嵌入到别的视图代码中，不用重复写表单的代码了，这正是ruby的思想，不做重复的工作。继续我们的new student的研究，我们把new student的表单填好后，点击create student 按钮，表单被提交到create的action里了，我们去看看create这个action
# 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
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]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。
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。
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。
4.destroy
<%= link_to 'Destroy', student, method: :delete, data: { confirm: 'Are you sure?' } %> 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。
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