Golang与MongoDB：灵活处理嵌入结构体及字段可见性

type User struct {
  Id      bson.ObjectId `json:"id,omitempty" bson:"_id,omitempty"`
  Name    string        `json:"name,omitempty" bson:"name,omitempty"`
  Secret  string        `json:"-,omitempty" bson:"secret,omitempty"` // Secret字段在JSON中被忽略
}

type adminUser struct {      
  User // 嵌入User结构体
  Secret  string        `json:"secret,omitempty" bson:"secret,omitempty"`
}

type adminUser struct {
    User `bson:",inline"` // 使用inline标签扁平化User的字段
    Secret string `json:"secret,omitempty" bson:"secret,omitempty"`
}

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"

    "gopkg.in/mgo.v2"
    "gopkg.in/mgo.v2/bson"
)

// User 结构体用于公共视图，不包含敏感信息
type User struct {
    Id   bson.ObjectId `json:"id,omitempty" bson:"_id,omitempty"`
    Name string        `json:"name,omitempty" bson:"name,omitempty"`
}

// adminUser 结构体用于管理员视图，包含所有信息
type adminUser struct {
    User   `bson:",inline"` // 扁平化User的字段
    Secret string        `json:"secret,omitempty" bson:"secret,omitempty"` // 敏感字段只在此处定义
}

// 模拟数据库连接
func getMongoSession() *mgo.Session {
    session, err := mgo.Dial("mongodb://localhost:27017/testdb")
    if err != nil {
        log.Fatalf("Failed to connect to MongoDB: %v", err)
    }
    session.SetMode(mgo.Monotonic, true)
    return session
}

// 初始化数据
func initData(session *mgo.Session) {
    c := session.DB("testdb").C("users")
    c.DropCollection() // 清空旧数据

    // 插入一个adminUser，包含Secret
    err := c.Insert(&adminUser{
        User: User{
            Id:   bson.NewObjectId(),
            Name: "John Doe",
        },
        Secret: "my_super_secret_key",
    })
    if err != nil {
        log.Printf("Failed to insert data: %v", err)
    }
    fmt.Println("Data initialized.")
}

// ServeJSON 辅助函数，用于返回JSON响应
func ServeJSON(w http.ResponseWriter, data interface{}) {
    w.Header().Set("Content-Type", "application/json")
    if err := json.NewEncoder(w).Encode(data); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
    }
}

// getUserHandler 处理普通用户请求
func getUserHandler(w http.ResponseWriter, r *http.Request) {
    session := getMongoSession()
    defer session.Close()

    userId := r.URL.Query().Get("id")
    if !bson.IsObjectIdHex(userId) {
        http.Error(w, "Invalid user ID", http.StatusBadRequest)
        return
    }

    var user User // 使用User结构体接收数据
    err := session.DB("testdb").C("users").FindId(bson.ObjectIdHex(userId)).One(&user)
    if err != nil {
        if err == mgo.ErrNotFound {
            http.Error(w, "User not found", http.StatusNotFound)
        } else {
            http.Error(w, err.Error(), http.StatusInternalServerError)
        }
        return
    }
    ServeJSON(w, &user) // JSON输出不含Secret
}

// getAdminUserHandler 处理管理员请求
func getAdminUserHandler(w http.ResponseWriter, r *http.Request) {
    session := getMongoSession()
    defer session.Close()

    userId := r.URL.Query().Get("id")
    if !bson.IsObjectIdHex(userId) {
        http.Error(w, "Invalid user ID", http.StatusBadRequest)
        return
    }

    var adminUser adminUser // 使用adminUser结构体接收数据
    err := session.DB("testdb").C("users").FindId(bson.ObjectIdHex(userId)).One(&adminUser)
    if err != nil {
        if err == mgo.ErrNotFound {
            http.Error(w, "User not found", http.StatusNotFound)
        } else {
            http.Error(w, err.Error(), http.StatusInternalServerError)
        }
        return
    }
    ServeJSON(w, &adminUser) // JSON输出包含Secret
}

func main() {
    session := getMongoSession()
    defer session.Close()
    initData(session)

    // 获取已插入的用户ID
    var tempAdminUser adminUser
    session.DB("testdb").C("users").Find(nil).One(&tempAdminUser)
    exampleUserID := tempAdminUser.Id.Hex()
    fmt.Printf("Example User ID: %s\n", exampleUserID)

    http.HandleFunc("/user", getUserHandler)
    http.HandleFunc("/admin/user", getAdminUserHandler)

    fmt.Println("Server started on :8080")
    fmt.Println("Try: http://localhost:8080/user?id=" + exampleUserID)
    fmt.Println("Try: http://localhost:8080/admin/user?id=" + exampleUserID)
    log.Fatal(http.ListenAndServe(":8080", nil))
}