mongodb数组写操作

mongodb中一条document格式为：

先想给数组jobs添加一个元素，如{"job_name":"name1", "finish_time":1435043559}

C++代码如下:

    shared_ptr<MongoSession> session = MongoSessionFactory::GetSession();    BSONObjBuilder condition;    condition.append("finish_date", finish_date);    BSONObjBuilder rec;     rec.append("job_name", job_name);    rec.append("finish_time", finish_time);     BSONObjBuilder recs;    recs.append("jobs", rec.obj());    BSONObjBuilder set;    set.append("$push", recs.obj());    session->get().update(config.wind_db + ".scheduler_job_finish_time", mongo::Query(condition.obj()), set.obj());

其中数组修改器$push作用是给数组添加元素，且如果数组不存在时会自动创建．