通过

$match

聚合管道中的 $match 阶段用于筛选与指定条件匹配的文档。 其与 find 操作类似，但在聚合管道中使用，以缩小传递至下一阶段的文档。 通过减少后续阶段中需要处理的文档数量，此阶段对于优化性能非常有用。

语法

{
  $match: {
    <query>
  }
}

参数

参数 说明
<query> 一个标准的 MongoDB 查询文档，指定文档必须满足的条件。

示例

请考虑商店集合中的这个示例文档。

{
  "_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"
  ]
}

示例 1：使用字符串比较来匹配文档

此查询检索“ _id 7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5”的文档：

db.stores.aggregate([
    {
      $match: {
        "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5"
      }
    }
])

此查询返回以下结果：

[
    {
        "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
        "name": "Lakeshore Retail | DJ Equipment Stop - Port Cecile",
        "location": {
            "lat": 60.1441,
            "lon": -141.5012
        },
        "staff": {
            "employeeCount": {
                "fullTime": 2,
                "partTime": 0
            }
        },
        "sales": {
            "salesByCategory": [
                {
                    "categoryName": "DJ Headphones",
                    "totalSales": 35921
                },
                {
                    "categoryName": "DJ Cables",
                    "totalSales": 1000
                }
            ],
            "fullSales": 3700
        },
        "promotionEvents": [],
        "tag": [
            "#ShopLocal",
            "#NewArrival",
            "#NewArrival",
            "#FreeShipping"
        ],
        "company": "Lakeshore Retail",
        "city": "Port Cecile",
        "lastUpdated": "2025-08-04T05:57:04.619Z",
        "storeOpeningDate": "2024-09-12T10:21:58.274Z"
    }
]

示例 2：使用数字比较来匹配文档

此查询检索总销售额大于 $35,000 的所有商店：

db.stores.aggregate([
    {
      $match: {
        "sales.totalSales": { $gt: 35000 }
      }
    },
    // Limit the result to the first 3 documents
    { $limit: 3 },
      // Include only _id and name fields in the output 
    { $project: { _id: 1, name: 1 } } 
])

此查询返回的前三个结果为：

[
  {
    "_id": "8345de34-73ec-4a99-9cb6-a81f7b145c34",
    "name": "Northwind Traders | Bed and Bath Place - West Oraland"
  },
  {
    "_id": "57cc4095-77d9-4345-af20-f8ead9ef0197",
    "name": "Wide World Importers | Bed and Bath Store - West Vitafort"
  },
  {
    "_id": "560099f8-325f-4c35-a4e5-2e0879eb95af",
    "name": "Wide World Importers | Bed and Bath Depot - North Maritzaberg"
  }
]

示例 3：匹配子文档中的文档

此查询检索在 DJ 混音器上折扣为 15% 的所有存储：

db.stores.aggregate([
    {
      $match: {
        "promotionEvents.discounts": {
          $elemMatch: {
            "categoryName": "DJ Mixers",
            "discountPercentage": 15
          }
        }
      }
    },
    // Limit the result to the first 3 documents
    { $limit: 3 },
      // Include only _id and name fields in the output 
    { $project: { _id: 1, name: 1 } } 
])

此查询返回的前三个结果为：

[
  {
    "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
    "name": "Lakeshore Retail | DJ Equipment Stop - Port Cecile"
  },
  {
    "_id": "3c7eda41-23a1-4226-abf6-17ee9e851b5b",
    "name": "Boulder Innovations | DJ Equipment Bazaar - New Ceasarview"
  },
  {
    "_id": "63831a7d-13a9-4d8b-bf1d-ac004057f96d",
    "name": "Contoso, Ltd. | DJ Equipment Shop - Reillyfurt"
  }
]

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