Joins in mongoDB

Question

I am new to MongoDB. I have designed a app with a follower/following like Twitter style

My schema is as follows

UserSchema :

    username:'Alex',
    pass:'salted',
    likes:'200'

FollowSchema

    uid : {
        type: Schema.ObjectId,
        ref: 'User'
    },
    fid : {
        type: Schema.ObjectId,
        ref: 'User'
    }

First of all, is this a scalable design ?

If so, I would like to get all the users except logged in user and find if each user is following the logged in user or not.

I am thinking of Aggregation or mapreduce but not sure how to approach.Any help is appreciated.

Thx

score 2 · Accepted Answer · edited May 23 '17 at 10:34

2

Yes this looks like a good way to do it, according to this post here:

as well as the mongodb website:

edited May 23 '17 at 10:34

Community

answered May 04 '16 at 07:06

Andrew Brown

Libu Mathew · Answer 2 · 2016-09-24T23:56:17.980

1

In mongodb there is no join operation. In mongoose you can use populate().

Follow.find({}).populate('uid').populate('fid').exec(function (e, d) {
   if(e){
      res.json(e);
   }
   else {
      res.json(d);
   }
});

edited Sep 24 '16 at 23:56

answered May 04 '16 at 07:12

Libu Mathew

Thanks...But how do I get all the users first and then find if a specific user is following the logged in users.As per your code, unless the user is in the follow document,I would not get the user details in results. – Karthik Renkarajan May 04 '16 at 19:55

2 Answers2