你能告诉我什么是最好的实践创造HAS_ONE关系？

Could you tell me whats the best practice to create has_one relations?

f.e。如果我有一个用户模型，它必须有一个配置文件...

f.e. if i have a user model, and it must have a profile...

我怎么能做到呢？

一个解决方案是：

# user.rb
class User << ActiveRecord::Base
  after_create :set_default_association

  def set_default_association
    self.create_profile
  end
end

不过，这并不显得很干净...任何建议？

But that doesnt seem very clean... Any suggests?

推荐答案

创建HAS_ONE关系最好的做法是使用ActiveRecord的回调 before_create ，而不是 after_create 。或者使用更早的回调和处理孩子没有通过自己的验证步骤的问题（如果有的话）。

Best practice to create has_one relation is to use the ActiveRecord callback before_create rather than after_create. Or use an even earlier callback and deal with the issues (if any) of the child not passing its own validation step.

由于：

如何做到这一点：

# in your User model...
has_one :profile
before_create :build_default_profile

private
def build_default_profile
  # build default profile instance. Will use default params.
  # The foreign key to the owning User model is set automatically
  build_profile
  true # Always return true in callbacks as the normal 'continue' state
       # Assumes that the default_profile can **always** be created.
       # or
       # Check the validation of the profile. If it is not valid, then
       # return false from the callback. Best to use a before_validation 
       # if doing this. View code should check the errors of the child.
       # Or add the child's errors to the User model's error array of the :base
       # error item
end