通过

$in

运算符 $in 将字段的值与可能值的数组匹配。 运算符 $in 筛选出字段值等于指定的数值的文档。

语法

{
    field: {
        $in: [ listOfValues ]
    }
}

参数

参数 DESCRIPTION
field 要匹配的字段
[listOfValues] 一个用于与指定字段进行比较的值数组

例子

让我们了解 stores 数据集中的示例 json 的用法。

{
  "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
  "name": "Lakeshore Retail | DJ Equipment Stop - Port Cecile",
  "location": {
    "lat": 60.1441,
    "lon": -141.5012
  },
  "staff": {
    "totalStaff": {
      "fullTime": 2,
      "partTime": 0
    }
  },
  "sales": {
    "salesByCategory": [
      {
        "categoryName": "DJ Headphones",
        "totalSales": 35921
      }
    ],
    "fullSales": 3700
  },
  "promotionEvents": [
    {
      "eventName": "Bargain Blitz Days",
      "promotionalDates": {
        "startDate": {
          "Year": 2024,
          "Month": 3,
          "Day": 11
        },
        "endDate": {
          "Year": 2024,
          "Month": 2,
          "Day": 18
        }
      },
      "discounts": [
        {
          "categoryName": "DJ Turntables",
          "discountPercentage": 18
        },
        {
          "categoryName": "DJ Mixers",
          "discountPercentage": 15
        }
      ]
    }
  ],
  "tag": [
    "#ShopLocal",
    "#SeasonalSale",
    "#FreeShipping",
    "#MembershipDeals"
  ],
  "company": "Lakeshore Retail",
  "city": "Port Cecile",
  "lastUpdated": {
    "$date": "2024-12-11T10:21:58.274Z"
  }
}

示例 1 - 使用 $in 运算符作为比较查询来查找具有特定类别促销的商店

查询查找通过促销活动在“熏鲑鱼”或“Anklet”类别中提供折扣的商店。

db.stores.find(
  {
    "promotionEvents.discounts.categoryName": {
      "$in": ["Smoked Salmon", "Anklets"]
    }
  },
  {
    "name": 1,
    "promotionEvents.discounts.categoryName": 1
  }
).limit(1)

这会返回以下结果：

{
  "_id": "48fcdab8-b961-480e-87a9-19ad880e9a0a",
  "name": "Lakeshore Retail | Jewelry Collection - South Nicholas",
  "promotionEvents": [
    {
      "discounts": [
        {"categoryName": "Anklets"},
        {"categoryName": "Cufflinks"}
      ]
    },
    {
      "discounts": [
        {"categoryName": "Anklets"},
        {"categoryName": "Brooches"}
      ]
    },
    {
      "discounts": [
        {"categoryName": "Rings"},
        {"categoryName": "Bracelets"}
      ]
    },
    {
      "discounts": [
        {"categoryName": "Charms"},
        {"categoryName": "Bracelets"}
      ]
    },
    {
      "discounts": [
        {"categoryName": "Watches"},
        {"categoryName": "Pendants"}
      ]
    }
  ]
}

示例 2 - 将 $in 运算符用作指定值或值集的数组中的数组表达式

查询搜索指定的存储和筛选文档，其中至少有一个 discountPercentage 位于任意 promotionEvents.discounts 位置为 15 或 20。 它使用点表示法路径和$in运算符来匹配数组层次结构中的嵌套折扣值。

db.stores.find(
  {
    "_id": "48fcdab8-b961-480e-87a9-19ad880e9a0a",
    "promotionEvents.discounts.discountPercentage": { $in: [15, 20] }
  },
  {
    "_id": 1,
    "name": 1,
    "promotionEvents.discounts": 1
  }
)

查询返回数组discounts包含任一discountPercentage1520元素或元素且仅显示complete discounts array这些文档的文档。

{
  "_id": "48fcdab8-b961-480e-87a9-19ad880e9a0a",
  "name": "Lakeshore Retail | Jewelry Collection - South Nicholas",
  "promotionEvents": [
    {
      "discounts": [
        { "categoryName": "Anklets", "discountPercentage": 12 },
        { "categoryName": "Cufflinks", "discountPercentage": 9 }
      ]
    },
    {
      "discounts": [
        { "categoryName": "Anklets", "discountPercentage": 23 },
        { "categoryName": "Brooches", "discountPercentage": 12 }
      ]
    },
    {
      "discounts": [
        { "categoryName": "Rings", "discountPercentage": 10 },
        { "categoryName": "Bracelets", "discountPercentage": 21 }
      ]
    },
    {
      "discounts": [
        { "categoryName": "Charms", "discountPercentage": 9 },
        { "categoryName": "Bracelets", "discountPercentage": 13 }
      ]
    },
    {
      "discounts": [
        { "categoryName": "Watches", "discountPercentage": 20 },
        { "categoryName": "Pendants", "discountPercentage": 7 }
      ]
    }
  ]
}

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