用于更新操作的golang中的Mongodb Arrayfilter查询

package main

import (
    "context"
    "fmt"
    "log"

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

type User struct {
    ID       int      `bson:"_id"`
    Username string   `bson:"username"`
    Email    string   `bson:"email"`
    Tags     []string `bson:"tags"`
}

func main() {
    // 连接到Mongodb数据库
    client, err := mongo.Connect(context.TODO(), options.Client().ApplyURI("mongodb://localhost:27017"))
    if err != nil {
        log.Fatal(err)
    }

    // 选择数据库和集合
    collection := client.Database("mydb").Collection("users")

    // 构建查询条件和更新操作
    filter := bson.M{"_id": 1}
    update := bson.M{
        "$set": bson.M{
            "tags.$[elem]": "updated",
        },
    }
    arrayFilters := options.ArrayFilters{
        Filters: []interface{}{
            bson.M{"elem": bson.M{"$eq": "old"}},
        },
    }

    // 执行更新操作
    result, err := collection.UpdateOne(context.TODO(), filter, update, &options.UpdateOptions{
        ArrayFilters: &arrayFilters,
    })
    if err != nil {
        log.Fatal(err)
    }

    fmt.Printf("Updated %d document(s)\n", result.ModifiedCount)
}