ruby on rails 在model中使用enum的注意事项
Posted Still_Walking
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了ruby on rails 在model中使用enum的注意事项相关的知识,希望对你有一定的参考价值。
enum的作用是声名一个枚举属性来映射数据库里整型字段的值,并能通过这个属性来查询数据库。
可以这么使用(事例来自官方),比如:
class Conversation < ActiveRecord::Base
enum status: [ :active, :archived ]
end
或者
class Conversation < ActiveRecord::Base
enum status: { active: 0, archived: 1 }
end
# conversation.update! status: 0 conversation.active! conversation.active? # => true conversation.status # => "active" # conversation.update! status: 1 conversation.archived! conversation.archived? # => true conversation.status # => "archived" # conversation.status = 1 conversation.status = "archived" conversation.status = nil conversation.status.nil? # => true conversation.status # => nil
关于查询的:Conversation.where(status: [:active, :archived]) Conversation.where.not(status: :active)
这样使用很方便,但是使用这个enum时候一定要非常注意,你可能注意到了,它会产生一些方法。比如上面,它产生了:active!
,active?
,status= 等等。
如果你一不小心使用了:group属性,比如这样定义:
class Conversation < ActiveRecord::Base
enum status: {group: 0, single: 1}
end
运行时它会产生You tried to define an enum named "statuss" on the model "ConfirmAsset", but this will generate a class method "group", which is already defined by Active Record.这样的错误。
另外使用字段名称的时候也要注意,因为我得到了这样的错误:You tried to define an enum named "import" on the model "ConfirmAsset", but this will generate a instance method "import=", which is already defined by another enum.
以上是关于ruby on rails 在model中使用enum的注意事项的主要内容,如果未能解决你的问题,请参考以下文章