数组中的芒果搜索 [英] Mango search in Arrays

问题描述

我的文档结构如下:

{
  "Calibration": {
    "Presettings": {
      "Date": [
        {
          "Value": "2016-09-02 10:11",
          "Type": "generated"
        },
        {
          "Value": "2016-09-05",
          "Type": "schedule",
          "Duration": "5"
        }
      ]
    }
  }
}

我必须如何定义查询对象的选择器部分才能获取日期(值)小于或等于给定日期且具有 Type=='generated' 的所有文档?

How must I define the selector part of a query object to get all documents with dates (Value) less or equal to a given date and with Type=='generated'?

推荐答案

首先，您需要创建索引.我建议您在 Calibration.Presettings.Date 字段 上创建一个索引.

First, you need to create your index. I suggest that you create an index on the Calibration.Presettings.Date field.

您可以使用以下 JSON 对象来创建它:

You can use the following JSON object to create it:

{
  "index": {
    "fields": [
      "_id",
      "Calibration.Presettings.Date.[].Type"
    ]
  },
  "type": "json"
}

所以选择器应该是这样的:

So the selector would be like this :

{
  "selector": {
    "Calibration.Presettings.Date": {
      "$elemMatch": {
        "$and": [
          {
            "Type": "generated"
          },
          {
            "Value": {
              "$gte": "2016-09-01"
            }
          }
        ]
      }
    }
  }
}

我们在字段 Calibration.Pressettings.Date 上执行查询，这是一个 数组.由于它是一个数组，我们必须使用 $elemMatch 运算符.

We execute the query on the field Calibration.Pressettings.Date which is an Array. Since it's an array, we have to use the $elemMatch operator.

然后，我们有一个用于值和类型的$and条件.

Then, we have a $and condition for the Value and the Type.

日期的类型必须生成.With 既可以使用 $eq 运算符，也可以简单地使用这个简单的语法:{"field":"value"}.

The Type of the Date has to be generated. With can either use the $eq operator or simply use this simple syntax: {"field":"value"}.

最后，Date`s Value 必须大于或等于 X 日期.我们可以使用 $gte 运算符.

Finally, the Date`s Value must be greater or equal to X date. We can use the $gte operator.

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