rails 命令

建立新項目：rails new meetup -d mysql

migrate數據庫：rake db:create db:migrate

生成controller：rails generate controller welcome

生成model：rails g model event name:string description:text is_public:boolean capacity:integer

查看路由: rake routes

rake幫助查看：rake -T

scaffold生成簡易crud程序命令：rails g scaffold person name:string bio:text birthday:date

生成新的欄位：rails g migration add_status_to_events

行數統計：rake stats

查看log：tail -f log/development.log

 

一對多：

建立、刪除、查找、
u = User.first
a = Article.new(...........)
a.user_id = u.id
a.saveclass Category < ActiveRecord::Base
    has_many :events
end

class Event < ActiveRecord::Base
  belongs_to :category
  # ...
end

e = Event.first
e.attendees.destroy_all # 一筆一筆刪除 e 的 attendee，並觸發 attendee 的 destroy 回呼
e.attendees.delete_all # 一次砍掉 e 的全部 attendees，不會觸發個別 attendee 的 destroy 回呼

a = e.attendees.find(3)
attendees = e.attendees.where( :name => 'ihower' ) #查出來的是數組

一對一：

多對多class Event < ActiveRecord::Base
    has_one :location # 單數
    #...
end

class Location < ActiveRecord::Base
    belongs_to :event # 單數
end

class Event < ActiveRecord::Base
    has_many :event_groupships
    has_many :groups, :through => :event_groupships
end

class EventGroupship < ActiveRecord::Base
    belongs_to :event
    belongs_to :group
end

class Group < ActiveRecord::Base
    has_many :event_groupships
    has_many :events, :through => :event_groupships
end

一對多建立@attendee = @event.attendees.build
一對多路由：

resources :events do
  resources :attendees, :controller => 'event_attendees'
end

一對一建立
一對一路由@location = @event.build_location

　 resources :user do
　　resource :role, :controller => 'user_role'
　end

Nested Model

user的model里加上    accepts_nested_attributes_for :role, :allow_destroy => true, :reject_if => :all_blank

user 的new.html里加上

<%= f.fields_for :role do |role_form| %>
<p>
<%= role_form.label :name, "Role Name" %>
<%= role_form.text_field :name %>

<% unless role_form.object.new_record? %>
<%= role_form.label :_destroy, 'Remove:' %>
<%= role_form.check_box :_destroy %>
<% end %>
</p>
<% end %>

user的helper加上

def setup_user(user)
　　user.build_role unless user.role
　　user
end

user的controller改爲

def event_params
	params.require(:event).permit(:name, :description, :category_id, :location_attributes => [:name] )
end

提交表單改爲

<%= form_for setup_event(@event), :url => events_path do |f| %>