需要協助從 mongodb 文件獲取元素並使用 go mongo 驅動程式更新其值

php小編草莓在這裡為大家介紹一個常見的需求：如何從MongoDB文件中獲取元素並使用Go Mongo驅動程式更新其值。 MongoDB是一種流行的NoSQL資料庫，而Go是一種強大的程式語言，兩者的結合可以帶來許多好處。在本文中，我們將探討如何使用Go Mongo驅動程式來實現這個需求，幫助您更能理解並應用這個技術。

問題內容

嘿，我正在使用 go.mongodb.org/mongo-driver 套件來使用 golang。這是我的程式碼：

package src

import (
    "context"
    "fmt"
    "log"

    "go.mongodb.org/mongo-driver/bson"
    "go.mongodb.org/mongo-driver/mongo"
    "go.mongodb.org/mongo-driver/mongo/options"
)

var (
    client      *mongo.client
    stickerscol *mongo.collection
)

func init() {
    log.println("setting up database...")
    var err error
    client, err = mongo.connect(context.background(), options.client().applyuri(envars.dburl))
    if err != nil {
        log.fatal(err)
    }
    log.println("connected to database")
    stickerscol = client.database("stickersbot").collection("stickers")
    chatcol = client.database("stickersbot").collection("chat")
}

func changedefaultpack(userid int64, stickername string, format string) error {
    fmt.println(userid, stickername, format)
    filter := bson.m{
        "_id":                      userid,
        "stickers.stickername":     stickername,
        "stickers.stickerpacktype": format,
    }
    updateother := bson.m{
        "$set": bson.m{
            "stickers.$[elem].isdefault": false,
        },
    }
    update := bson.m{
        "$set": bson.m{
            "stickers.$.isdefault": true,
        },
    }
    arrayfilters := options.arrayfilters{
        filters: []interface{}{bson.m{"elem.stickerpacktype": format}},
    }
    updateoptions := options.update().setarrayfilters(arrayfilters)
    _, err := stickerscol.updatemany(context.todo(), filter, updateother, updateoptions)
    if err != nil {
        return err
    }
    ok, err := stickerscol.updateone(context.background(), filter, update, options.update().setupsert(true))
    if err != nil {
        return err
    }
    if ok.modifiedcount == 0 {
        fmt.println("no document matched")
        return fmt.errorf("no document matched")
    }
    return err
}

這是資料庫結構：

...
{
  "_id": 1633375527,
  "stickers": [
    {
      "stickerpacktype": "static",
      "stickername": "gVtOy_1633375527_by_ChadManBot",
      "isdefault": true
    },
    {
      "stickerpacktype": "animated",
      "stickername": "zIjsa_1633375527_by_ChadManBot",
      "isdefault": true
    },
    {
      "stickerpacktype": "video",
      "stickername": "bJBle_1633375527_by_ChadManBot",
      "isdefault": true
    },
    {
      "stickerpacktype": "static",
      "stickername": "iujiw_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "video",
      "stickername": "CHnqb_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "XKJUP_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "animated",
      "stickername": "pCFlC_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "animated",
      "stickername": "jGGgt_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "animated",
      "stickername": "cTxyA_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "animated",
      "stickername": "ZfYXO_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "xJUkA_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "HIvsY_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "WIHFQ_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "OqjtE_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "QNysO_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "OrTsT_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "FzROg_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "QUBcT_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "NsZfM_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "AkxVM_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "Ddvus_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "LXfHV_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "sTaMv_1633375527_by_ChadManBot",
      "isdefault": false
    },
    {
      "stickerpacktype": "static",
      "stickername": "vppgK_1633375527_by_ChadManBot",
      "isdefault": false
    }
  ],
  "stickerpackcount": 2
}
...

我需要我的程式碼是找到與給定id 和貼圖類型相符的貼紙包列表，並將其預設值設為false 並將傳遞給func 的包的預設值設為true。

基本上只是將其中一個設定為預設值，而其他設定為非預設值。有人可以解釋為什麼這個函數回傳未找到文件嗎？

解決方法

當有多個欄位符合時，您應該使用 $elemmatch 運算子。否則，$ 運算子不起作用。請參閱 使用多個欄位符合更新嵌入文件。

且您不需要 updatemany 來更新單一文件中的多個陣列元素。請改用 updateone。

這是基於您的程式碼和資料的示範：

package main

import (
    "context"
    "fmt"
    "log"

    "go.mongodb.org/mongo-driver/bson"
    "go.mongodb.org/mongo-driver/mongo"
    "go.mongodb.org/mongo-driver/mongo/options"
)

var (
    client      *mongo.client
    stickerscol *mongo.collection
)

func init() {
    log.println("setting up database...")
    var err error
    client, err = mongo.connect(context.background(), options.client().applyuri("mongodb://localhost"))
    if err != nil {
        log.fatal(err)
    }
    log.println("connected to database")
    stickerscol = client.database("stickersbot").collection("stickers")
}

func changedefaultpack(userid int64, stickername string, format string) error {
    fmt.println(userid, stickername, format)
    filter := bson.m{
        "_id": userid,
        "stickers": bson.m{
            "$elemmatch": bson.m{
                "stickername":     stickername,
                "stickerpacktype": format,
            },
        },
    }
    updateother := bson.m{
        "$set": bson.m{
            "stickers.$[elem].isdefault": false,
        },
    }
    arrayfilters := options.arrayfilters{
        filters: []interface{}{bson.m{"elem.stickerpacktype": format}},
    }
    updateoptions := options.update().setarrayfilters(arrayfilters)
    result, err := stickerscol.updateone(context.background(), filter, updateother, updateoptions)
    if err != nil {
        return err
    }
    log.printf("update other: %+v\n", result)

    update := bson.m{
        "$set": bson.m{
            "stickers.$.isdefault": true,
        },
    }
    ok, err := stickerscol.updateone(context.background(), filter, update, options.update().setupsert(true))
    if err != nil {
        return err
    }
    log.printf("update default: %+v\n", ok)
    if ok.modifiedcount == 0 {
        fmt.println("no document matched")
        return fmt.errorf("no document matched")
    }
    return err
}

func main() {
    if err := changedefaultpack(1633375527, "ddvus_1633375527_by_chadmanbot", "static"); err != nil {
        panic(err)
    }
}

執行演示，您將觀察到文件發生以下變更：

--- before.json 2023-06-27 00:34:32.721978745 +0800
 after.json  2023-06-27 00:34:59.489836137 +0800
@@ -4,7 +4,7 @@
     {
       "stickerpacktype": "static",
       "stickername": "gVtOy_1633375527_by_ChadManBot",
-      "isdefault": true
+      "isdefault": false
     },
     {
       "stickerpacktype": "animated",
@@ -104,7 +104,7 @@
     {
       "stickerpacktype": "static",
       "stickername": "Ddvus_1633375527_by_ChadManBot",
-      "isdefault": false
+      "isdefault": true
     },
     {
       "stickerpacktype": "static",

以上是需要協助從 mongodb 文件獲取元素並使用 go mongo 驅動程式更新其值的詳細內容。更多資訊請關注PHP中文網其他相關文章！