ios - Firebase 数据过滤

Question

我有以下 Firebase JSON 数据结构；

  {
  "USERS": {
    "YjGJsvCb58OsTThv6JLmK1dMuHr1": {
      "Email": "test@test.com"
    },
    "zQpb7o18VzYsSoTQtT9DNhOqTUn2": {
      "Email": "test2@test.com"
    }
  },
  "POSTS": {
    "-KSe4eJyenccPoC5T0zP": {
      "addedByUser": "YjGJsvCb58OsTThv6JLmK1dMuHr1",
      "content": "Post 1",
      "cost": "600",
      "duration": "Quarterly",
      "latitude": "51.5099850000001",
      "longitude": "-0.133528614416432",
      "timestamp": "Tue 27 Sep"
    },
    "-KSe4q1DXoulArzWm_Zm": {
      "addedByUser": "YjGJsvCb58OsTThv6JLmK1dMuHr1",
      "content": "Post 2",
      "cost": "550",
      "duration": "Monthly",
      "latitude": "51.5100199999855",
      "longitude": "-0.133507191218496",
      "timestamp": "Tue 27 Sep"
    }
  }
}

我想过滤POSTS并获取所有持续时间为每月或以用户为准的POSTS已选择。正如您所看到的，每个 POST 都分配有一个 AutoID。

我正在寻找的结果应该会输出:

  {
  "-KSe4q1DXoulArzWm_Zm": {
    "addedByUser": "YjGJsvCb58OsTThv6JLmK1dMuHr1",
    "content": "Post 2",
    "cost": "550",
    "duration": "Monthly",
    "latitude": "51.5100199999855",
    "longitude": "-0.133507191218496",
    "timestamp": "Tue 27 Sep"
  }
}

但我一生都无法搜索 AutoID。我已经尝试了几乎所有的 queryFor 和 observe 方法。我已经搜索过 StackOverflow，但似乎没有解决方案有效。我的数据结构是否正确？我需要 AutoID 的原因是某些帖子可能是相同的。

任何帮助将不胜感激。

Answer 1

试试这个:-

FIRDatabase.database().reference().queryOrdered(byChild: "POSTS").queryEqual(toValue: "monthly").observeSingleEvent(of: .value, with: {(snap) in


    if let postsDict = snap.value as! [String:AnyObject]{

       for each in postsDict {

          print(each)

            }

    }else{

    //That username doesnt exists.

    }

})