ruby on rails

 最好的参考资料：ruby文档 http://guides.ruby-china.org

CRUD：

C：user = User.create(name:"David", occupation: "Code Artist") 或者

user = User. new

user.name = "David"

user.occupation = "Code Artist"

user.save

R: 

users＝User.all

    user=User.first

nemo=User.find_by(name:'Nemo')

users = User.where(name: 'David' , occupation: 'Code Artist' ).order( 'created_at DESC' )

详见：http://guides.ruby-china.org/active_record_basics.html

数据验证：p＝Person.new

validates :name, presence: true #是否存在

p.valid?来进行测试，错误信息存储在p.errors.messages

errors[:attribute].any? 验证某个属性是否报错

validates :terms_of_service, acceptance: { accept: 'yes' } #决定接受什么值，默认为'1'

class Library < ActiveRecord::Base

   has_many :books

   validates_associated :books

end

#验证关联对象，只需在one上写vali....

validates :legacy_code , format: { with: /\ A [a-zA- Z ]+\z/,

     message: "only allows letters" }

#正则表达式

validates :subdomain , exclusion: { in : %w(www us ca jp),

     message: "%{value} is reserved." }

＃不包含在后方类型中

validates :size , inclusion: { in : %w(small medium large),

     message: "%{value} is not a valid size" }

＃包含

validates :name , length: { minimum: 2 }

   validates :bio , length: { maximum: 500 }

   validates :password , length: { in : 6 .. 20 }

   validates :registration_number , length: { is: 6 }

＃长度

详见：http://guides.ruby-china.org/active_record_validations.html

migrate的用法：http://blog.youkuaiyun.com/felomeng/article/details/21121509

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

新建一系列包括m，v，c：$ rails g scaffold person name:string bio:text birthday:date

停止服务器：lsof |grep 3000  然后kill pid 20409