Ruby on Rails where 嵌套关系查询

Question

我从这个问题中学会了如何使用 where 查询与关系。

Ruby on Rails where query with relations

但是，我仍然无法正确处理这个嵌套案例。 如何使摘要控制器索引工作？

型号

User
  has_many :projects, dependent: :destroy
  has_many :reasons, through: :projects
  has_many :summaries, through: :projects, source: :reasons
  has_many :entries, through: :projects

Project
  belongs_to :user
  has_many :reasons
  has_many :entries, through: :reasons

Reasons
  belongs_to :project
  has_many :entries, dependent: :destroy 
  has_many :summaries, dependent: :destroy 

Summary
  belongs_to :reason

Entry
  belongs_to :reason

EntriesController

  # GET /entries
  def index
    entries     = current_user.entries
    updated_at  = params[:updated_at]

    # Filter with updated_at for reloading from mobile app
    if updated_at.present?

      # THIS WORKS!!!!!!!!!!!!!
      entries = entries.joins(:reason).where("reasons.updated_at > ?", Time.at(updated_at.to_i))

    # Get all non deleted objects when logging in from mobile app
    else
      entries = entries.where(deleted: false)
    end

    render json: entries
  end 

SummariesController

  # GET /summaries
  def index
    summaries   = current_user.summaries
    updated_at  = params[:updated_at]

    # Filter with updated_at for reloading from mobile app
    if updated_at.present?



      #THIS DOES NOT WORK, what can I do?????
      summaries = summaries.joins(:reason).where("reasons.updated_at > ?", Time.at(updated_at.to_i))



    # Get all non deleted objects when logging in from mobile app
    else
      summaries = summaries.where(deleted: false)
    end

    render json: summaries
  end  

@iOS 上的错误日志

错误：错误域=com.alamofire.error.serialization.response Code=-1011 “请求失败：内部服务器错误 (500)”UserInfo={NSUnderlyingError=0x1481b9030 {错误域=com.alamofire.error.serialization。 response Code=-1016 "请求失败：不可接受的内容类型：text/html"

@Error 登录 Heroku

[1m[36mUser Load (2.0ms)[0m [1mSELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT 1[0m 2016-04-30T07:48:18.909397+00:00 app[web.1]：在 4 毫秒内完成 500 个内部服务器错误（ActiveRecord：2.0 毫秒） 2016-04-30T07:48:18.910250+00:00 app[web.1]: ActiveRecord::ConfigurationError（在 Reason 上找不到名为“reason”的关联；也许你拼错了？）：

Answer 1

首先，您以非常随意的方式引用reasons。 User has_many reasons 到 projects，那为什么不走那条路呢？

current_user.joins(:reasons).where(reasons.updated_at > ?", updated_at)

其次，更具体地针对您的错误：您的关系定义 has_many :summaries, through: :projects, source: :reasons 似乎已损坏，因为 projects 没有任何 summaries。

考虑将has_many :summaries, through: :reasons 添加到您的Project 模型，然后在User 中使用has_many :summaries, through: :projects。