Question

这是一个例子。（注意：firebase中的数据没有改变。这是为了消除一个变量。换句话说，我加载了数据，现在它是静态的。）

我正在测试我是否从orderByChild电话中收到了正确的结果。

我在下面的curl命令中执行此操作。请注意，我正在按照@FrankvanPuffelen的建议对返回值进行排序。

我每次将orderby查询的限制增加一个。

我希望看到上一个查询返回的先前数据和一个新行。

但是我看到的数据显示在一个较大的限制内，并没有达到一个较低的限制。

参见从限制5到限制6的过渡：

限制1

$ curl 'https://nysenate.firebaseio.com/bills.json?orderBy="publishedDateTime"&limitToFirst=1&print=pretty'|grep publishedDateTime|sort
      "publishedDateTime" : "2015-06-05T09:16:05",

限制2

$ curl 'https://nysenate.firebaseio.com/bills.json?orderBy="publishedDateTime"&limitToFirst=2&print=pretty'|grep publishedDateTime|sort
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:16:05",

限制3

$ curl 'https://nysenate.firebaseio.com/bills.json?orderBy="publishedDateTime"&limitToFirst=3&print=pretty'|grep publishedDateTime|sort
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:21:05",

限制4

$ curl 'https://nysenate.firebaseio.com/bills.json?orderBy="publishedDateTime"&limitToFirst=4&print=pretty'|grep publishedDateTime|sort
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:21:05",
      "publishedDateTime" : "2015-06-05T09:21:05",

限制5

$ curl 'https://nysenate.firebaseio.com/bills.json?orderBy="publishedDateTime"&limitToFirst=5&print=pretty'|grep publishedDateTime|sort
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:21:05",
      "publishedDateTime" : "2015-06-05T09:21:05",
      "publishedDateTime" : "2015-06-05T11:21:11",

限制6

$ curl 'https://nysenate.firebaseio.com/bills.json?orderBy="publishedDateTime"&limitToFirst=6&print=pretty'|grep publishedDateTime|sort
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:16:05",
      "publishedDateTime" : "2015-06-05T09:21:05",
      "publishedDateTime" : "2015-06-05T09:21:05",
      **"publishedDateTime" : "2015-06-05T10:36:09",**  **why did this not show in the previous query??**
      "publishedDateTime" : "2015-06-05T11:21:11",

Answer 1

当您打印整个JSON时，可以找到答案，而不是只打算使用一个属性：

curl 'https://nysenate.firebaseio.com/bills.json?orderBy="publishedDateTime"&limitToFirst=5&print=pretty'

给出：

{
  "-JrERWNEH-hvrBEdd0OR" : {
    "2015-J2697" : {
      "fullName" : "Jack M. Martins",
      "publishedDateTime" : "2015-06-05T09:16:05",
      "resolution" : true
    }
  },
  "-JrERWRs0dTPeYJRRtc7" : {
    "2015-J2700" : {
      "fullName" : "Neil D. Breslin",
      "publishedDateTime" : "2015-06-05T09:16:05",
      "resolution" : true
    }
  },
  "-JrERWWNBUJU78Q_ho6p" : {
    "2015-J2705" : {
      "fullName" : "Neil D. Breslin",
      "publishedDateTime" : "2015-06-05T09:21:05",
      "resolution" : true
    }
  },
  "-JrERW_jQto1EX1G8_2w" : {
    "2015-J2712" : {
      "fullName" : "Neil D. Breslin",
      "publishedDateTime" : "2015-06-05T09:21:05",
      "resolution" : true
    }
  },
  "-JrERWdyWKDJujg1d-Ms" : {
    "2015-J2717" : {
      "fullName" : "Gustavo Rivera",
      "publishedDateTime" : "2015-06-05T11:21:11",
      "resolution" : true
    }
  }
}

我删除了一些属性，但重要的是现在可以看到完整的JSON结构。你有一个嵌套对象：

bills
  -JrERWNEH-hvrBEdd0OR
    2015-J2697
      fullName
      publishDateTime
      resolution

我希望您已经定义了这样的索引：

{
  "bills": {
    ".indexOn": "publishDateTime"
  }
}

因此，对于名为publishDateTime的子/财产，Firebase会在每个帐单下立即。但遗憾的是，该法案下不存在这样的子/财产，因为该值实际上存储的层次更深。 Firebase索引深度为一级，因此您的索引为空。

当您查询账单时，Firebase会以其他一些未确定的顺序订购账单。

解决方案是摆脱不必要的嵌套。使用push-id（例如-JrERWNEH-hvrBEdd0OR）来识别账单或使用您自己的ID（例如2015-J2697）。只要你摆脱了嵌套，这两种方法都有效。

了解Firebase orderByChild

1 个答案: