Updating 2 mongoose schemas in an api call - node.js

Question

Currently I'm trying to update Two different User Schema's in an api call.
The first schema is logged in user schema, we give it a name = Tom
The second schema is other users who signup for the app, we give it a name = John
The schema code
schema.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var bcrypt = require('bcrypt-nodejs');
var UserSchema = new Schema({
name: String,
username: { type: String, required: true, index: { unique: true }},
password: { type: String, required: true, select: false },
followers: [{ type: Schema.Types.ObjectId, ref: 'User'}],
following: [{ type: Schema.Types.ObjectId, ref: 'User'}],
followersCount: Number,
followingCount: Number
});
module.exports = mongoose.model('User', UserSchema);
The api name is '/follow/:user_id', what I want to achieve is . Whenever user Tom follows other user's like John, Tom's following field will be updated as well as John's follower field.
My current attempt (req.decoded.id is the logged in user)
api.js
// The first way
apiRouter.post('/follow/:user_id', function(req, res) {
User.findOneAndUpdate(
{
_id: req.decoded.id,
following: { $ne: req.params.user_id }
},
{
$push: { following: req.params.user_id},
$inc: { followingCount: 1}
},
function(err, currentUser) {
if (err) {
res.send(err);
return;
}
console.log(currentUser);
});
User.findOneAndUpdate(
{
_id: req.params.user_id,
followers: { $ne: req.decoded.id }
},
{
$push: { followers: req.decoded.id },
$inc: { followersCount: 1}
}, function(err, user) {
if(err) {
res.send(err);
return;
}
res.json({
message: "Successfully followed"
});
}
)
});
//Second way
apiRouter.post('/follow/:user_id', function(req, res) {
// find a current user that has logged in
User.update(
{
_id: req.decoded.id,
following: { $ne: req.params.user_id }
},
{
$push: { following: req.params.user_id},
$inc: { followingCount: 1}
},
function(err) {
if (err) {
res.send(err);
return;
}
User.update(
{
_id: req.params.user_id,
followers: { $ne: req.decoded.id }
},
{
$push: { followers: req.decoded.id },
$inc: { followersCount: 1}
}
), function(err) {
if(err) return res.send(err);
res.json({ message: "Successfully Followed!" });
}
});
});
Both have problems,
The first way: The problem is, 'Can't set headers that already sent', because of the two separate mongoose query in one api call, it response twice that's why I get that error.
The second way: The problem is, the following field of logged in user(Tom) gets updated while the other user's followers field (John) return null. I console log both value and as well test it with POSTMAN chrome app.
Lend me your thoughts fellas!

Answer 1

The first route you took seems to be fine.
However, as #cdbajorin mentioned, the error "can't send headers that already sent" has nothing to do with mongoose but the fact that you're trying to set the header after sending a response to the client already. (see this lovely answer)
My suggestion would be to make sure that both database calls are successful before you send a response.
You may also want to look into a two phase commit in this situation, as MongoDB does not support traditional DB transactions and you're updating two documents, one at a time. If for some reason either database call fails, a procedure to recover to a stable state should be taken.

Answer 2

The first way can be improved in two ways. One is updating followers field inside the callback of updating following field. The other way is using async-waterfall. I suggest to go with async-waterfall(npm async-waterfall).

Answer 3

The second way it is correct (could be improved running both of them in parallel) I guess the problem is in another place. I don't know which framework you are using but i guess the field _id is from mongoDB and is an ObjectId and looks like that the decoded.id can be an objectId while the one that comes from the request is of course just a string. So I guess it is empty because it does not find any user with that string.
Try do make it an objectId out of that string ( reffering to req.params.user_id in the second query)