Godeps/_workspace/src/gopkg.in/mgo.v2/session.go
func (c *Collection) UpsertId(id interface{}, update interface{}) (info *ChangeInfo, err error) {
	return c.Upsert(bson.D{{"_id", id}}, update)
}
func (c *Collection) UpsertId(id interface{}, update interface{}) (info *ChangeInfo, err error) {
	return c.Upsert(bson.D{{"_id", id}}, update)
}
func ( c * Collection ) UpsertId ( id interface { } , update interface { } ) ( info * ChangeInfo , err error ) { return c . Upsert ( bson . D { { " " , id } } , update ) }
// UpsertId is a convenience helper equivalent to:
//
//     info, err := collection.Upsert(bson.M{"_id": id}, update)
//
// See the Upsert method for more details.
UpsertId is a convenience helper equivalent to : info err : = collection . Upsert ( bson . M { _id : id } update ) See the Upsert method for more details .