code: func (self *Model) FindId(id bson.ObjectId) *Query {
  
  	return &Query{
  		collection: self.Collection,
  		connection: self.connection,
  		query:      bson.M{"_id": id},
  		multiple:   false,
  	}
  }
docs: /*
  If you have an object ID it is possible to find the matching document with this param.
  
  For example:
  	User := connection.Model("User")
  
  	user := &models.User{}
  
  	err := User.FindId(bson.ObjectIdHex("55dccbf4113c615e49000001")).Select("firstname").Exec(user)
  
  	if _, ok := err.(*mongodm.NotFoundError); ok {
  		//no records were found
  	} else if err != nil {
  		//database error
  	} else {
  		fmt.Println("%v", user)
  	}
  
  */