Naming a Route
get 'home/index', as: "different_name"
会得到prefix: different_name代替home_index, 这个是路径的名字。
get 'home/ping', to: "home#pong"
to方法，定义到哪个控制器的哪个action。 这会改变默认的控制器的action。而控制器会指向view。
Paramter
通过浏览器输入的URI Pattern ，可以导向控制器的某个action
在router.rb中
resources :posts
get ':year(/:month(/:day))', to: 'posts#index'
Verb URI Pattern Controller#Action
GET /:year(/:month(/:day))(.:format) posts#index
解释：这里参数:year是必须的,括号里的是可选的。
http://localhost:3000/2018/01/01
Started GET "/2018/01/01" for 127.0.0.1 at 2018-06-18 09:52:25 +0800
Processing by PostsController#index as HTML
Parameters: {"year"=>"2018", "month"=>"01", "day"=>"01"}
Rendering posts/index.html.erb within layouts/application
Post Load (0.1ms) SELECT "posts".* FROM "posts"
↳ app/views/posts/index.html.erb:16
Rendered posts/index.html.erb within layouts/application (1.8ms)
Completed 200 OK in 39ms (Views: 37.7ms | ActiveRecord: 0.1ms)
解释：在controller的index动作中， 你可以利用params[]来存取定义在URL中的值。
valid_date?方法，找不到出处？
def index
if Date.valid_date?(params[:year].to_i, params[:month].to_i, params[:day].to_i)
start_date = Date.parse("#{params[:day]}.#{params[:month]}.#{params[:year]}")
end_date = start_date
elsif Date.valid_date?(params[:year].to_i, params[:month].to_i, 1)
start_date = Date.parse("1.#{params[:month]}.#{params[:year]}")
end_date = start_date.end_of_month
elsif params[:year] && Date.valid_date?(params[:year].to_i, 1, 1)
start_date = Date.parse("1.1.#{params[:year]}")
end_date = start_date.end_of_year
end
if start_date && end_date
@posts = Post.where(published_on: start_date..end_date)
end
end
constraints(constraints={})
用于限制url
get ':year(/:month(/:day))', to: 'posts#index', constraints: {year: /\d{4}/, month: /\d{2}/, day: /\d{2}/ }
也可以接受块：
constraints(id: /\d+\.\d+/) do
resources :posts
end
加入🚫后，id只能输入1.1或者10.11的格式，否则会报告Routing Error.
Redirect(*args, &block)方法
用于返回到其他path。设置比较复杂。
get ':year/:month/:day', to: redirect("/%{year}/0%{month}/0%{day}"), constraints: { year: /\d{4}/, month: /\d{1}/, day: /\d{1}/ }
还必须加上👇，否则不能导航到控制器的index动作。
get ':year(/:month(/:day))', to: 'posts#index', constraints: {year: /\d{4}/, month: /\d{2}/, day: /\d{2}/ }
我的理解：第一行代码是返回到第二行代码的路径，然后再指向控制器的index动作。
only和except方法:用做resources的参数。
Nested Resources
如果使用scaffold在改router.rb后，先修改路径：
resources :posts do
resources :comments
end
然后根据路径对控制器行为修改：
- before_action :set_post #@post = Post.find(params[:post_id])
- index, new, create, update, destroy都需要修改。
最后是视图view还需要对comments/*.html.erb全部修改。包括参数的传递，连接的修改。删除没用的表格的字段。
shallow resources就是一个便捷的路径写法。
resources :posts do
resources :comments, only:[:index, :new, :create]
end
resources :comments, except:[:index, :new, :create]
无需细记。
