小编Muk*_*wat的帖子

我知道了:

$ git pull origin master
From https://bitbucket.org/tecgenome/chl-v2.0-html
 * branch            master     -> FETCH_HEAD
fatal: refusing to merge unrelated histories

我如何避免或通过该错误消息？

我试图从查询下面的集合表单中获取数据:

     db.getCollection('jobs').aggregate(
    {$match :{"slug":"bath-room-designer-for-whole-floor-772000"}},
????{$unwind: "$job_activity"},
????{$lookup: {
????????????"from":"users",
????????????"localField":"job_activity.user_id",
????????????"foreignField":"_id",
????????????"as": "user_details"
????????}
????},
????{$unwind: { path: "$user_details", preserveNullAndEmptyArrays: false } },
????{$group: {
????????????????"_id": "$_id", 
                "Job_detail": {"$push": "$job_activity"},
                "job_activity": {"$push": "$job_activity"},
????????????????"user_details": {"$push": "$user_details"}
????????????}
????}
????
)

但是,如果$ match的集合中存在datat,则会导致空数据,但此slug不存在job_activity

有谁可以帮助谢谢

我们如何在findmongodb的方法中使用别名,就像我们在mySQL中一样:

select user_id as id from users

请提供一些帮助,谢谢!