來自 mongoDB 的一項數(shù)據(jù)是{    "_id" : ObjectId("5536def4e4b0644323e219a8"),    "title" : "The Title",    "description" : "The Description",    "timeStamp" : "21/04/2015",    "category" : "news",    "url" : "http://www.example.com",    "source" : "Evening Times",    "mainStory" : "This is the main story."}在我的代碼中，結(jié)構(gòu)是type NewsData struct {    Title       string `bson: "title" json: "title"`    TimeStamp   string `bson: "timeStamp" json: "timeStamp"`    Description string `bson: "description" json: "description"`    MainStory   string `bson: "mainStory" json:"mainStory"`}然后我用下面的代碼來提取信息err = conn.Find(nil).Select(bson.M{"title": 1, "timeStamp": 1, "description": 1, "mainStory": 1}).All(&result)但是，當我打印result出來時，timeStampand 的mainStory值為空。我查了文檔，說mgo是把key取小寫的，所以mongoDB的key如果是大寫的，就出問題了。我該如何解決這個問題？