Rails JBuilder 递归查找

Question

我用的是Rails4，有一些简单的模型如下：

class Question < ActiveRecord::Base
  # columns (id, text)
  has_many :answers
end

class Answer < ActiveRecord::Base
  # columns (id, text, next_question_id)
  belongs_to :question
end

您可以看到一个答案有一个 next_question_id 列，将用于查找另一个问题。我想生成这样的树结构 json：

{
  "text": "This is question 1",
  "answers": [
    {
      "text": "This is answer a",
      "next_question": {
        "text": "This is question 2",
        "answers": [
          {
            "text": "This is answer c",
            "next_question":
          }
        ]
      }
    },
    {
      "text": "This is answer b",
      "next_question": {
        "text": "This is question 2",
        "answers": [
          {
            "text": "This is answer d",
            "next_question":
          }
        ]
      }
    }
  ]
}

如何使用 JBuilder 实现此目的？我尝试了解决方案 here，但我无法将 json 参数传递给辅助函数。

Answer 1

渲染树的标准方法是使用递归部分。要实现这一点，您首先需要像这样向 Answer 模型添加一个方法。

def next_question
  Question.find(next_question_id) if next_question_id  
end

(提示：或者你可以在你的Answer模型上设置一个belongs_to :next_question, class_name: Question关联)

然后你创建一个像 _question.json.jbuilder 这样的部分：

json.(question,:id, :text)
json.answers question.answers do |answer|
  json.(answer, :id, :text)
  json.partial!(:question, question: answer.next_question) if answer.next_question
end

然后在控制器中，您将调查中的第一个问题放在 @first_question 变量中。

最后一件事：在你看来你写

json.partial! :question, question: @first_question

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