Go语言中MongoDB嵌入式结构体与多视图数据管理

import (
    "go.mongodb.org/mongo-driver/bson/primitive" // 或 mgo/bson
)

// User 结构体定义了用户的基本信息，适用于公共API视图。
// Secret 字段通过 json:"-" 标记，表示在JSON序列化时应被忽略。
type User struct {
    Id     primitive.ObjectID `json:"id,omitempty" bson:"_id,omitempty"`
    Name   string             `json:"name,omitempty" bson:"name,omitempty"`
    Secret string             `json:"-" bson:"secret,omitempty"` // 在公共视图中不暴露Secret
}

{
  "id": "60c72b2f9e4e6b001a8b4567",
  "name": "John Doe"
}

// adminUser 结构体尝试通过嵌入User来继承字段
type adminUser struct {
    User // 嵌入User结构体
    Secret string `json:"secret,omitempty" bson:"secret,omitempty"`
}

// adminUser 结构体使用 bson:",inline" 标签来扁平化嵌入的User字段
type adminUser struct {
    User   `bson:",inline"` // 使用 inline 标签，将User的字段提升到adminUser的顶层
    Secret string `json:"secret,omitempty" bson:"secret,omitempty"`
}

package main

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

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

// User 优化后的结构体，不包含任何敏感或特定视图的字段
type User struct {
    Id   primitive.ObjectID `json:"id,omitempty" bson:"_id,omitempty"`
    Name string             `json:"name,omitempty" bson:"name,omitempty"`
}

// adminUser 最终的结构体，包含所有字段，适用于管理员视图
type adminUser struct {
    User   `bson:",inline"` // 嵌入User并扁平化其字段
    Secret string `json:"secret,omitempty" bson:"secret,omitempty"` // 仅在adminUser中定义Secret
}

// 模拟数据库连接
var client *mongo.Client

func init() {
    // 假设已经连接到MongoDB
    clientOptions := options.Client().ApplyURI("mongodb://localhost:27017")
    var err error
    client, err = mongo.Connect(context.TODO(), clientOptions)
    if err != nil {
        log.Fatal(err)
    }
    err = client.Ping(context.TODO(), nil)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("Connected to MongoDB!")

    // 插入一些测试数据（如果集合为空）
    collection := client.Database("testdb").Collection("users")
    count, _ := collection.CountDocuments(context.TODO(), bson.M{})
    if count == 0 {
        _, _ = collection.InsertOne(context.TODO(), bson.M{
            "name":   "John Doe",
            "secret": "supersecretpassword",
        })
        _, _ = collection.InsertOne(context.TODO(), bson.M{
            "name":   "Jane Smith",
            "secret": "anothersecret",
        })
        fmt.Println("Inserted test data.")
    }
}

// getUserPublicHandler 模拟公共API，只返回User的公共字段
func getUserPublicHandler(w http.ResponseWriter, r *http.Request) {
    idStr := r.URL.Query().Get("id")
    if idStr == "" {
        http.Error(w, "ID is required", http.StatusBadRequest)
        return
    }
    objID, err := primitive.ObjectIDFromHex(idStr)
    if err != nil {
        http.Error(w, "Invalid ID format", http.StatusBadRequest)
        return
    }

    collection := client.Database("testdb").Collection("users")
    var user User // 使用公共User结构体
    err = collection.FindOne(context.TODO(), bson.M{"_id": objID}).Decode(&user)
    if err != nil {
        if err == mongo.ErrNoDocuments {
            http.Error(w, "User not found", http.StatusNotFound)
        } else {
            http.Error(w, err.Error(), http.StatusInternalServerError)
        }
        return
    }

    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(user)
}

// getUserAdminHandler 模拟管理员API，返回adminUser的所有字段，包括Secret
func getUserAdminHandler(w http.ResponseWriter, r *http.Request) {
    // 实际应用中这里会有权限验证
    idStr := r.URL.Query().Get("id")
    if idStr == "" {
        http.Error(w, "ID is required", http.StatusBadRequest)
        return
    }
    objID, err := primitive.ObjectIDFromHex(idStr)
    if err != nil {
        http.Error(w, "Invalid ID format", http.StatusBadRequest)
        return
    }

    collection := client.Database("testdb").Collection("users")
    var adminUser adminUser // 使用adminUser结构体
    err = collection.FindOne(context.TODO(), bson.M{"_id": objID}).Decode(&adminUser)
    if err != nil {
        if err == mongo.ErrNoDocuments {
            http.Error(w, "User not found", http.StatusNotFound)
        } else {
            http.Error(w, err.Error(), http.StatusInternalServerError)
        }
        return
    }

    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(adminUser)
}

func main() {
    http.HandleFunc("/public/user", getUserPublicHandler)
    http.HandleFunc("/admin/user", getUserAdminHandler)
    fmt.Println("Server listening on :8080")
    log.Fatal(http.ListenAndServe(":8080", nil))
}