如何从活动模型序列化中的关联模型中提取数据？

Question

我正在使用 active_model_serializers gem 将响应发送为 JSON。我从关联模型中提取数据，但如何仅从 questions table 获取那些数据，其中 UserType 等于 clients.UserType.

ClientSerializer:

class ClientSerializer < ActiveModel::Serializer
  attributes :id, :username, :access_token, :UserType

  has_many :questions, include: :all
end

和QuestionSerializer:

class QuestionSerializer < ActiveModel::Serializer
  attributes :id, :question, :client_id, :UserType
  belongs_to :user
end

这里是输出 JSON:

{
    "id": 4,
    "username": "171fdkjgku",
    "access_token": "77NVccAJG7hEKSGQUcKkSip5",
    "UserType": 1,
    "questions": [
        {
            "id": 1,
            "question": "Lorem Ipsum",
            "client_id": 4,
            "UserType": 1
        },
        {
            "id": 2,
            "question": "Lorem Ipsum 2",
            "client_id": 4,
            "UserType": 0
        },
        {
            "id": 3,
            "question": "Lorem Ipsum 3",
            "client_id": 4,
            "UserType": 1
        }
    ]
}

预期输出JSON：

{
    "id": 4,
    "username": "171fdkjgku",
    "access_token": "77NVccAJG7hEKSGQUcKkSip5",
    "UserType": 1,
    "questions": [
        {
            "id": 1,
            "question": "Lorem Ipsum",
            "client_id": 4,
            "UserType": 1
        },
        {
            "id": 3,
            "question": "Lorem Ipsum 3",
            "client_id": 4,
            "UserType": 1
        }
    ]
}

Answer 1

您可以通过自己定义 questions 方法并在其中获取范围内的问题来实现此目的：

class ClientSerializer < ActiveModel::Serializer
  attributes :id, :username, :access_token, :UserType, :questions

  def questions
    ques = self.object.questions.where(UserType: self.object.UserType).to_a
    ActiveModel::ArraySerializer.new(ques, each_serializer: QuestionSerializer).as_json
  end
end

如何从活动模型序列化中的关联模型中提取数据？

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