[英]ActiveRecord: Do I need both belongs_to and has_one
I have 2 models, namely user and userprofile . 我有2个模型,即user和userprofile 。 There is a one-to-one relationship between user and userprofile.
用户和userprofile之间存在一对一的关系 。
class Userprofile < ActiveRecord::Base
attr_accessible :fname, :lname, :iswoman, :age, :urlphoto, :user_id
belongs_to: user
end
class User < ActiveRecord::Base
attr_accessible :name, :provider, :uid
has_one: userprofile
end
I'd like to know whether I need both class to set the connection or having just either belongs_to or has_one is enough? 我想知道我是否需要两个类来设置连接,或者只需要belongs_to或has_one就足够了? The same is true for the other methods, such as has-many .
其他方法也是如此,例如has-many 。
You define the association wherever you will need it. 您可以在任何需要的地方定义关联。 If at some point you need to say
user.userprofile
, then include has_one :userprofile
in User
. 如果在某些时候你需要说
user.userprofile
,那么在User
包含has_one :userprofile
。 Likewise, if you need to say userprofile.user
, then include belongs_to user
in Userprofile
. 同样,如果您需要说
userprofile.user
,那么在Userprofile
包含belongs_to user
。
In other words, associations are relative. 换句话说,关联是相对的。 You can specify that model A
has_one :b
without specifying that model B belongs_to :a
. 您可以指定模型A
has_one :b
而不指定模型B belongs_to :a
。 You simply define what you need. 您只需定义所需内容即可。 The same goes for one-to-many and many-to-many associations.
对于一对多和多对多关联也是如此。
Just be sure to have migrated user_id
to the "userprofiles" table. 确保已将
user_id
迁移到“userprofiles”表。
Having just a belongs_to relationship between userprofiles and user does default to has_one. 在userprofiles和user之间只有一个belongs_to关系,默认为has_one。 However, it would be wise (Rails-proper) to specify the association on both models.
但是,在两个模型上指定关联是明智的(Rails-proper)。
After all, if you wanted a has_many association (etc) you would want to specify that. 毕竟,如果你想要一个has_many关联(etc),你会想要指定它。
Check out http://guides.rubyonrails.org/association_basics.html for more info 查看http://guides.rubyonrails.org/association_basics.html了解更多信息
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