我正在使用這樣的結構type User struct {    Username  string    `json: "username" bson: "username"`    FirstName string    `json: "firstName" bson: "firstName"`    LastName  string    `json: "lastName" bson: "lastName"`    Email     string    `json: "email" bson: "email"`    Gender    string    `json: "gender" bson: "gender"`    Password  string    `json: "password" bson: "password"`    Enabled   bool      `json: "enabled" bson: "enabled"`    BirthDate time.Time `json: "birthDate" bson: "birthDate"`    CreatedAt time.Time `json: "createdAt" bson: "createdAt"`    UpdatedAt time.Time `json: "updatedAt" bson: "updatedAt"`    collection *mongo.Collection}然后使用查詢數據func (u *User) FindByUsername(userName string) error {    var ctx, _ = context.WithTimeout(context.Background(), 10*time.Second)    filter := bson.M{"username": userName}    err := u.collection.FindOne(ctx, filter).Decode(&u)    return err}我得到的結果是{"Username":"jbond","FirstName":"","LastName":"","Email":"[email protected]","Gender":"Male","Password":"","Enabled":true,"BirthDate":"0001-01-01T00:00:00Z","CreatedAt":"0001-01-01T00:00:00Z","UpdatedAt":"0001-01-01T00:00:00Z"}大多數數據都已填充，但駝峰式字段除外，當我從控制臺查詢時，數據就在那里> db.users.find().pretty(){    "_id" : ObjectId("xxxxxxxxxxxxxxxxxxxxxxxx"),    "username" : "jbond",    "firstName" : "James",    "lastName" : "Bond",    "email" : "[email protected]",    "password" : "",    "enabled" : true,    "gender" : "Male",    "birthDate" : {        "type" : {            "code" : "function Date() {\n    [native code]\n}"        }    },    "createdAt" : {        "type" : {            "code" : "function Date() {\n    [native code]\n}"        },        "default" : {            "code" : "function now() {\n    [native code]\n}"        }    },    "updatedAt" : {        "type" : {            "code" : "function Date() {\n    [native code]\n}"        },        "default" : {            "code" : "function now() {\n    [native code]\n}"        }    }}我不明白為什么要全部小寫?；蛘呶义e過了什么？