Question

我正在尝试使用带有关系的查询和updated_at比较。

当我使用updated_at参数发送此查询时，我只想获取由updated_at日期过滤的最新原因，但是它会过滤项目的updated_at，而不是原因updated_at。

如何解决此问题以使用updated_at过滤器获取原因数据？

@Getting reason with updated_at filter

https://server.com/api/v1/entries?updated_at=2016-05-02T01:12:57.204Z

@Model

User
  has_many :projects
  has_many :reasons, through: :projects

Project
  belongs_to :user
  has_many :reasons

Reasons
  belongs_to :project

@Reasons Controllers

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

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

      # This is my first try, but it shows error because of relations
      # reasons = reasons.where("updated_at > ?", DateTime.parse(updated_at))      

      # This shows reasons data, but it only compares updated_at in Project data, not reasons data...
      reasons = reasons.joins(:project).where("projects.updated_at > ?", DateTime.parse(updated_at))

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

    render json: reasons
  end

Answer 1

您提取projects.updated_at，但如果我理解正确，您需要提取reasons.updated_at

reasons = reasons.joins(:project).where("reasons.updated_at > ?", DateTime.parse(updated_at))

为我生产输出

GET http://localhost:3000/reasons/index?updated_at=2016-05-04T06:43:19.280Z

[
    {
        "id": 2,
        "name": "R2",
        "project_id": 3,
        "created_at": "2016-05-04T06:43:19.280Z",
        "updated_at": "2016-05-04T06:43:19.280Z",
        "deleted": false
    },
    {
        "id": 3,
        "name": "R3",
        "project_id": 3,
        "created_at": "2016-05-04T06:43:25.895Z",
        "updated_at": "2016-05-04T06:43:25.895Z",
        "deleted": false
    }
]

没有任何过滤器

GET http://localhost:3000/reasons/index

[
    {
        "id": 1,
        "name": "R1",
        "project_id": 3,
        "created_at": "2016-05-04T06:43:11.044Z",
        "updated_at": "2016-05-04T06:43:11.044Z",
        "deleted": false
    },
    {
        "id": 2,
        "name": "R2",
        "project_id": 3,
        "created_at": "2016-05-04T06:43:19.280Z",
        "updated_at": "2016-05-04T06:43:19.280Z",
        "deleted": false
    },
    {
        "id": 3,
        "name": "R3",
        "project_id": 3,
        "created_at": "2016-05-04T06:43:25.895Z",
        "updated_at": "2016-05-04T06:43:25.895Z",
        "deleted": false
    }
]

Answer 2

它只是改为reason.updated_at，谢谢！

reasons = reasons.joins(:project).where("reasons.updated_at > ?", DateTime.parse(updated_at))

Ruby on Rails，其中查询与关系和updated_at进行比较

2 个答案: