选择嵌套数组对象-Mgo

Question

The problem I face at the minute is trying to select a nested object array so that I can append data to it or just insert into it. The following is the json in Mongo i'm trying to query:

{
"username":"[e-mail]",
"Course":[
  {
     "Date":{
        "DatePlayed":"Fri Jul 21 2017 00:00:00 GMT 0100 (GMT Daylight Time)",
        "Course":{
           "CoursePlayed":"testerCourse",
           "holes":[
              {
                 "holeno":0,
                 "score":"",
                 "putts":"",
                 "penalty":"",
                 "bunker":"",
                 "green":"",
                 "fairway":""
              }
           ]
        }
     }
  }
 ]
}

What I am trying to do is select the object within the holes array so that I can either append or just enter data into the object. The structs that I am using are as follows:

type Hole struct {
Holeno  int64  `json:"holeno" bson:"holeno"`
Score   string `json:"score"  bson:"score"`
Putts   string `json:"putts"  bson:"putts"`
Penalty string `json:"penalty" bson:"penalty"`
Bunker  string `json:"bunker" bson:"bunker"`
Green   string `json:"green"bson:"green"`
Fairway string `json:"fairway"bso   n:"fairway"`
}

type Round struct {
Date struct {
    DatePlayed string `json:"DatePlayed" bson:"DatePlayed"`
    Course     struct {
        CoursePlayed string   `json:"CoursePlayed" bson:"CoursePlayed"`
        Holes        [18]Hole `json:"Hole" bson:"Hole"`
    } `json:"Course" bson:"Course"`
} `json:"Date" bson:"Date"`
} 

The attempt I have made so fair which has failed is as follows

err = u.Find(bson.M{"username": Uname}).Select(bson.M{"Course.Date.Course.holes": 1}).One(&Game)

Game is just Game:=Round{}