共用方式為

$position

$position運算子是用來指定數位中應該插入新元素的位置。 當您需要在數位中的特定索引插入專案，而不是將它附加至結尾時，這個運算子很有用。

語法

{
  $push: {
    <arrayField>: {
      $each: [<value1>, <value2>],
      $position: <index>
    }
  }
}

參數

參數 Description
<arrayField> 檔中包含要更新之陣列的欄位。
<value1>, <value2>, ... 要插入陣列中的值。
<index> 應該插入值的位置。

範例

請參考商店集合中的此範例檔。

{
    "_id": "0fcc0bf0-ed18-4ab8-b558-9848e18058f4",
    "name": "First Up Consultants | Beverage Shop - Satterfieldmouth",
    "location": {
        "lat": -89.2384,
        "lon": -46.4012
    },
    "staff": {
        "totalStaff": {
            "fullTime": 8,
            "partTime": 20
        }
    },
    "sales": {
        "totalSales": 75670,
        "salesByCategory": [
            {
                "categoryName": "Wine Accessories",
                "totalSales": 34440
            },
            {
                "categoryName": "Bitters",
                "totalSales": 39496
            },
            {
                "categoryName": "Rum",
                "totalSales": 1734
            }
        ]
    },
    "promotionEvents": [
        {
            "eventName": "Unbeatable Bargain Bash",
            "promotionalDates": {
                "startDate": {
                    "Year": 2024,
                    "Month": 6,
                    "Day": 23
                },
                "endDate": {
                    "Year": 2024,
                    "Month": 7,
                    "Day": 2
                }
            },
            "discounts": [
                {
                    "categoryName": "Whiskey",
                    "discountPercentage": 7
                },
                {
                    "categoryName": "Bitters",
                    "discountPercentage": 15
                },
                {
                    "categoryName": "Brandy",
                    "discountPercentage": 8
                },
                {
                    "categoryName": "Sports Drinks",
                    "discountPercentage": 22
                },
                {
                    "categoryName": "Vodka",
                    "discountPercentage": 19
                }
            ]
        },
        {
            "eventName": "Steal of a Deal Days",
            "promotionalDates": {
                "startDate": {
                    "Year": 2024,
                    "Month": 9,
                    "Day": 21
                },
                "endDate": {
                    "Year": 2024,
                    "Month": 9,
                    "Day": 29
                }
            },
            "discounts": [
                {
                    "categoryName": "Organic Wine",
                    "discountPercentage": 19
                },
                {
                    "categoryName": "White Wine",
                    "discountPercentage": 20
                },
                {
                    "categoryName": "Sparkling Wine",
                    "discountPercentage": 19
                },
                {
                    "categoryName": "Whiskey",
                    "discountPercentage": 17
                },
                {
                    "categoryName": "Vodka",
                    "discountPercentage": 23
                }
            ]
        }
    ]
}

範例 1：在陣列欄位中的特定索引位置插入專案

此查詢會在特定文件陣列的#NewArrival第二個位置（索引 1）插入標籤tag。

db.stores.update({
    _id: "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5"
}, {
    $push: {
        tag: {
            $each: ["#NewArrival"],
            $position: 1
        }
    }
})

更新的文件在標籤陣列中具有下列值。

{
  "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
  "tag": [
    "#ShopLocal",
    "#NewArrival",
    "#FashionStore",
    "#SeasonalSale",
    "#FreeShipping",
    "#MembershipDeals"
  ]
}

相關內容

  • Last updated on