使用官方mongo-go-driver进行正确的通配符多字段查询

package main

import (
    "context"
    "fmt"

    "go.mongodb.org/mongo-driver/bson"
    "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"`
}

func main() {
    // 建立数据库连接
    client, err := mongo.Connect(context.Background(), options.Client().ApplyURI("mongodb://localhost:27017"))
    if err != nil {
        fmt.Println("Failed to connect to MongoDB:", err)
        return
    }

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

    // 创建正则表达式条件
    filter := bson.M{
        "$or": []bson.M{
            {"username": bson.M{"$regex": "pattern"}},
            {"email": bson.M{"$regex": "pattern"}},
        },
    }

    // 执行查询
    cursor, err := collection.Find(context.Background(), filter)
    if err != nil {
        fmt.Println("Failed to execute query:", err)
        return
    }
    defer cursor.Close(context.Background())

    // 遍历结果
    var users []User
    for cursor.Next(context.Background()) {
        var user User
        err := cursor.Decode(&user)
        if err != nil {
            fmt.Println("Failed to decode document:", err)
            continue
        }
        users = append(users, user)
    }

    // 输出结果
    fmt.Println(users)
}