Rails JBuilder递归查找

Question

我使用的是Rails 4，我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，它将用于查找另一个问题。我想要生成这样的树结构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实现这一目标？我尝试了解决方案here，但不能将json参数传递给助手函数。

Answer 1

绘制树的标准方法是使用递归的部分。要实现这一点，首先需要向Answer模型添加如下方法。

def next_question
  Question.find(next_question_id) if next_question_id  
end

(提示：您可以在Answer模型上设置一个belongs_to :next_question, class_name: Question关联。)

然后创建一个像_question.json.jbuilder这样的部分，如下所示：

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，您接受调查中的第一个问题，并将其放入@first_question变量。

最后一件事:在你看来

json.partial! :question, question: @first_question