ActiveModel Serializer中的自定义字段与另一个序列化程序(Custom field in ActiveModel Serializer with another serializer)

 我有has_many :sessions User模型。 但是对于一个特定的请求，我想根据请求设备平台（iOS，Android）仅发送一个会话。 
 
 问题是我有单独的UserSerializer和UserSessionSerializer ，我想在UserSerializer UserSessionSerializer作为选项UserSerializer给:session字段。 喜欢这个： 
 
# UsersController
render json: @user, serializer: UserSerializer, session: @session # @user's session founded by platform

# UserSerializer
attributes :id, :email, :username, :session

def session
  @instance_options[:session], serializer: UserSessionSerializer
end
 
 这是不可能的，因为据我所知，我只能在has_one和has_many传递序列化程序。 但我不想用has_many渲染JSON中的所有用户会话，只创建一个。 
 
 谢谢你的帮助！ 

I have User model with has_many :sessions. But for one particular request I want to send only one session based on request device platform (iOS, Android).
 
The problem is that I have separate UserSerializer and UserSessionSerializer and I want to pass UserSessionSerializer as option in UserSerializer for :session field. Like this:
 
# UsersController
render json: @user, serializer: UserSerializer, session: @session # @user's session founded by platform

# UserSerializer
attributes :id, :email, :username, :session

def session
  @instance_options[:session], serializer: UserSessionSerializer
end
 
It is impossible, because I can pass serializer only in has_one and has_many as I understand. But I don't want to render all user sessions in JSON with has_many, only founded one.
 
Thanks for any help!

原文：https://stackoverflow.com/questions/49793092