由于前一段时间太懒，直到今天才恢复学习。。。

Router转发

Router不仅仅会根据url来区分调用哪个函数……还会通过http请求的种类来划分。。。

       Prefix Verb   URI Pattern                  Controller#Action
welcome_index GET    /welcome/index(.:format)     welcome#index
         root GET    /                            welcome#index
     articles GET    /articles(.:format)          articles#index
              POST   /articles(.:format)          articles#create
  new_article GET    /articles/new(.:format)      articles#new
 edit_article GET    /articles/:id/edit(.:format) articles#edit
      article GET    /articles/:id(.:format)      articles#show
              PATCH  /articles/:id(.:format)      articles#update
              PUT    /articles/:id(.:format)      articles#update
              DELETE /articles/:id(.:format)      articles#destroy

如图所见，articles的index和create url相同，但却调用了不同的函数

值得注意的是patch这种请求类型，是个新玩意http://tools.ietf.org/html/rfc5789 ，能只更新一部分内容

深入理解看这个： https://ihower.tw/blog/archives/6483

Block

用

之类的语法

好像经常出问题……换成do |article| ... end就好了，大概是因为中间的函数如果接受了一个Hash作为参数，本身的{}会发生一些奇怪的问题

link_to

<%= link_to 'My Blog', controller: 'articles' %>

和

<%= link_to 'My Blog', articles_path %>好像是差不多的，不过在articles的外部用第一种居多，内部用第二种

method: :delete, data: { confirm: 'Are you sure?' }

method对应路由表的VERB

Model的一些设置。。。

数据验证

其实是一个函数……不过没括号真心爽

关联

创建新表时就要

rails generate model Comment commenter:string body:text article:references

You can also consider references as a kind of type. For instance, if you run:

rails generate model photo title:string album:references

It will generate an album_id column. You should generate these kinds of fields when

you will use a belongs_to association, for instance. references also supports

polymorphism, you can enable polymorphism like this:

rails generate model product supplier:references

之后有几种配置：

belongs_to
has_one (through)
has_many (through)
has_and_belongs_to_many

http://guides.ruby-china.org/association_basics.html

has_many :comments, dependent: :destroy

再之后如果是从属的话在路由表里可以搞：

resouces :articles do
    :comments
end

错误

  <% if @article.errors.any? %>
  <div id="error_explanation">
    <h2><%= pluralize(@article.errors.count, "error") %> prohibited
      this article from being saved:</h2>
    <ul>
    <% @article.errors.full_messages.each do |msg| %>
      <li><%= msg %></li>
    <% end %>
    </ul>
  </div>
  <% end %>

Path

 new_article GET    /articles/new(.:format)      articles#new
 edit_article GET    /articles/:id/edit(.:format) articles#edit
 article GET    /articles/:id(.:format)      articles#show

查看路由表时我们可以看到prefix一列，那一列加上_path就是url的变量了。。

如articles_path, edit_article_path(@article)之类的

局部模板

文件名以_开头，调用<% render 'template_name; %>渲染，不需要开头下划线

CURD简易速查。。。

@article = Article.find(params[:id])
if (@article.update(article_params))
@articles = Article.all
@article = Article.new(article_params)
if @article.save
@article.destroy

嵌套路由

<h2>Add a comment:</h2>
<%= form_for([@article, @article.comments.build]) do |f| %>
  <p>
    <%= f.label :commenter %><br>
    <%= f.text_field :commenter %>
  </p>
  <p>
    <%= f.label :body %><br>
    <%= f.text_area :body %>
  </p>
  <p>
    <%= f.submit %>
  </p>
<% end %>

Ruby on Rails (2)