通过

$binarySize（数据大小运算符）

  • 项目

$binarySize 运算符用于返回二进制数据字段的大小。 当处理存储的二进制数据（如图像、文件或任何其他二进制内容）时，这非常有用。 $binarySize 的参数应为字符串或二进制值。

语法

使用 $binarySize 运算符的语法如下所示：

{
  $binarySize: "<field>"
}

参数

说明
<field> 要获取其二进制大小的字段。

示例

让我们通过以下示例 json 来了解用法。

{
  "_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"
  ]
}

投影二进制字段的大小

db.stores.aggregate([
  {
    $project: {
      name: 1,          
      dataSize: {
        $binarySize: "$name" // Calculate the binary size of the string data
      }
    }
  },
  // Limit the result to the first 3 documents
  { $limit: 3 }  
])

此查询将返回以下文档。

[
  {
    "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
    "name": "Lakeshore Retail | DJ Equipment Stop - Port Cecile",
    "dataSize": 50
  },
  {
    "_id": "649626c9-eda1-46c0-a27f-dcee19d97f41",
    "name": "VanArsdel, Ltd. | Musical Instrument Outlet - East Cassie",
    "dataSize": 57
  },
  {
    "_id": "8345de34-73ec-4a99-9cb6-a81f7b145c34",
    "name": "Northwind Traders | Bed and Bath Place - West Oraland",
    "dataSize": 53
  }
]

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