前端学 Ruby：熟悉Rails

class BooksController < ApplicationController
    def index
        @books = Book.all
    end
end

rails generate model user userName:string email:string # 创建 user 模型，模型为 user，数据库中会以 users 展示
rails console # 进入命令行控制台
# 创建
@user = User.new(userName => 'johan', email => 'johan101@.qq.com') 
@user.save
# 还有一种是 create，创建记录，并存在数据库
@user =  User.create(userName => 'johan', email => 'johan101@.qq.com')
# 读取
# 获取所有的用户
users = User.all
# 返回第一个用户
user = User.first
# 返回第一个名为 johan 的用户
johan = User.find_by(name: 'johan')
# 更新
user = User.find_by(name: 'johan')
user.name = 'elaine'
user.save
# 或者是直接用关键字 update
user.update(name: 'elaine')
# 删除
# 删除所有用户
User.destroy_all 
# 删除名为 johan 的用户
user = User.find_by(name: 'johan')
user.destroy
# 其他
# find(*args)：根据主键查询特定记录
# find_by_sql(sql)：根据SQL语句查询
# exists?(id)：判断指定ID的记录是否存在
# create(attributes)：新增一条记录
# update(id, attributes)：根据ID来修改指定记录
# update_all(updates, conditions)：根据条件来修改一批记录

class User < ApplicationRecord
  validates :name, presence: true, length: { minimum: 2 } # 不能为空，长度最少是2个字符
  validates :email, presence: true, length: { maximun: 255 }, format: {
     with: EMAIL    
    }, uniqueness: { case_sensitive: false }, on: :create # 创建的时候该数据是唯一的
end

class User < ApplicationRecord
  validates :login, :email, presence: true
  before_validation :ensure_login_has_a_value
  private
    def ensure_login_has_a_value
      if login.nil?
        self.login = email unless email.blank?
      end
    end
end

# 生成迁移文件
rails g migration CreateJoinTableCustomerProduct customer product
# 迁移
rails db:migrate
# 版本回滚
rails db:rollback step=1

<h1><%= @article.title %></h1>
<%= image_tag @article.cover_image.url %>
<p><%= @article.content %></p>
<%= link_to "Edit", edit_article_path(@article) if Current.user.admin? %>

rails g controller Calendar show

Rails.application.routes.draw do
    resources :articles do    # /articles, /articles/1
     resources :comments     # /articles/1/comments, /comments/1
        member do
         post 'like'
            delete 'unlike'
        end
    end
    resouce :settings, only: [:show, :update] # 单数形式
    scope :profiles do
     get ':username', to: 'profiles#show', as: :user_profile
        post ':username/follow', to: 'profiles#follow', as: :follow_user
        delete ':username/follow', to: 'profiles#unfollow', as: :unfollow_user
    end
    get ':welcome', to: 'welcome#show' # GET /welcome
    root to: "articles#index" # 根目录
end

Rails.application.routes.draw do
    resources :post do
     get 'recent', :on => :collection
    end
    # 或者
    resources :post do
     collection do 
            get 'recent'
        end
    end
end

Rails.application.routes.draw do
    resources :post do
     member do
            get 'recent'
        end
    end
end

rails new myapp
rails new blog # 生成一个 blog 项目
rails new --api blog # 以 API 形式生成一 blog 项目
rails new -h # 查看所有命令行选项
rails new --api --database=postgresql --skip-test app # 创建一个数据库为 postgresql 的跳过测试的 api App项目

rails server
bin/rails server -e production -p 4000 # -e 环境 -p 端口

rails g model user email:string name:string # 创建 user 模型
rails g controller welcome hello # 生成 welcome 控制器，hello 函数
rails destroy controller welcome # 销毁 welcome 控制器所有配套的文件
rails g scaffold article title:string description:string body:text # 生成文章脚手架，视图、控制器、模型都生成
rails db:migrate # 同步到数据库
rails db:rollback step=1 #反悔命令 step 步骤
rails g migration AddUserGenderToUser gender:string # 修改数据库
# migration 基于的是 ActiveRecord::Migration

rails console
rails c