MongoDB - loopback.getCurrentContext() return null

[dongmai]

Hi everyone ,

Sorry for duplication, but I'm facing it again on nearly the latest version of loopback.
Here is my pacakge.json

{
  "name": "test",
  "version": "1.0.0",
  "main": "server/server.js",
  "scripts": {
    "start": "node .",
    "pretest": "eslint .",
    "posttest": "nsp check"
  },
  "dependencies": {
    "async": "^2.0.0",
    "compression": "^1.0.3",
    "cors": "^2.5.2",
    "helmet": "^1.3.0",
    "loopback": "^2.22.0",
    "loopback-boot": "^2.6.5",
    "loopback-component-explorer": "^2.4.0",
    "loopback-connector-mongodb": "^1.15.2",
    "loopback-datasource-juggler": "^2.39.0",
    "loopback-testing": "^1.2.0",
    "serve-favicon": "^2.0.1"
  },
  "devDependencies": {
    "eslint": "^2.5.3",
    "nsp": "^2.1.0"
  },
  "repository": {
    "type": "",
    "url": ""
  },
  "license": "UNLICENSED",
  "description": "test"
}

I've used a middleware to save current logged user data into context but it (getCurrentContext) always returned null when working with MongoDB (memory db works just fine.)

Bellow is my code,

app.use(loopback.token()); 
app.use(loopback.context());

app.use(function (req, res, next) {
    if (!req.accessToken) return next();

    app.models.User.findById(req.accessToken.userId, function(err, user) {
        if (err)   return next(err);
        if (!user) return next(new Error('No user with this access token was found.'));
        res.locals.currentUser = user;

        var loopbackContext = loopback.getCurrentContext();
        console.log('SERVER CTX?' +loopbackContext);
        if (loopbackContext) {
            loopbackContext.set('currentUser', user);
        }else{
            throw new Error('Current context is null.');
        }
        next();
    });
});

Can anyone please have a look ? Have I done something wrong ?

Thanks.

[0candy]

Thank you for pointing out this issue. Due to the instability, there are plans to deprecate this method.
See #1676

[syuhei176]

I had same problem, so I use loopback-connector-mongodb@1.15.1 . It work fine.

[beornharris]

Hey, I've run across this issue as well and just wanted to add some extra info (hope it helps somewhere). I had quick look through #1676 and didnt see anything that might help me.

I initially had an earlier version of loopback running, where I had no problems calling loopback.getCurrentContext() from within a remote method. I inadvertently updated to the current version, and started seeing issues.

I have created a demo repo (from scratch and using slc commands + customisation) to help explain.

https://github.com/beornharris/authtest

The issue I am experiencing is directly related to MongoDB and access tokens, as far as I can tell. Using the repo, the steps to replicate (in api explorer) are as follows (note: requires mongo instance) :

1. go to endpoint /Networks/{id}/contacts, enter an ID (value irrelevant) and empty object {} and submit. The console shows a context received at the endpoint (from common/models/network.js - Network.addContact)

CONTEXT:  Namespace {
  name: 'loopback',
  active: { accessToken: undefined },
  _set: [ null ],
  id:
   AsyncListener {
     create: [Function],
     flags: 15,
     before: [Function],
     after: [Function],
     error: [Function],
     uid: 2,
     data: null } }

1. Login using /Accounts/login

`{ "email": "user1@username.com", "password": "user1"}

and set the Access Token.

1. Repeat step 1 - the console shows

CONTEXT: null

Given this, I have a few other observations :

1. Issue does not occur when using memory DB connector
2. CONTEXT always shows null when ACL or AccessToken are set to mongo (this may well be by design, but I dont recall reading in the docs that these should ALWAYS be in-memory)
3. Error also occurs when using the built-in User model, and not just the derived (Account) model.

EDIT: @syuhei176 - I can confirm that the issue disappears with loopback-connector-mongodb@1.15.1

[dongmai]

Just try to use loopback-connector-mongodb@1.15.1 And it isn't working. :(

[beornharris]

@dongmai - just to confirm, to downgrade the mongo connector you did something like the following...

1. change package.json from "^1.15.2" to "1.15.1"
2. npm install

so it is using 1.15.1, and not minimum 1.15.1 ?

[josieusa]

I had the same issue using the same connector.
I solved it using my own PR and Node 6.3.1 locally:
strongloop/loopback-context#2
strongloop/loopback-context#11
So far, so good.
Of course, it's going to need more tests.
I'd also mention that it solved other similar issues with getCurrentContext() for me (see #1495 for examples).
Your mileage may vary

[dongmai]

@beornharris Yes, I've downgraded the version number in package json and re-run npm install of course.

Before downgrading it was working on local but not on remote server, and its the same after downgrading.

[evseevnn-zz]

Strange, after downgrading version i try use Model.observe('before save', ...)
and i get context === null inside.

@josieusa @bajtos
P.S. when i use mongo not work before save because by default for mongo version >=3 in connector no findOrCreate method. So, i improve dao.js for fire this event and get this problem. Maybe this depend on use notifyObserversOf? because after use this function i lose context. i tried to use commit of @josieusa but this not helped

[josieusa]

@beornharris I reproduced the issue using your authtest repo.
I'll verify my hypothesis that the issue could be caused by the es6-promise dependency of mongodb which is imported here:
https://github.com/mongodb/node-mongodb-native/blob/V2.2.19/package.json#L16
This hypothesis comes from my experience. In fact, in my PR 19 of loopback-context I just made some experiments, and it seems like it could fix problems with other Promise libraries, but only if these are used inside user code, and not some 3rd party library.
Sadly, I just tested that it didn't fix your issue, because that es6-promise is used in a 3rd party module (mongodb), and as I just said, my PR doesn't cover this case. (Also, I don't know yet if this is the root of this issue).
I'm not sure if this can be fixed by user code alone.
I know that you fixed your problem by changing versions, but other people may still be looking for proper solutions.

[Jeff-Lewis]

@josieusa try telling MongoDB to use cls-bluebird instead and then use cls-hooked instead of cls when initializing cls-bluebird.

In MongoClient.connect we can pass in the promiseLibrary to use. Now I'm not sure if there is an easy way to tell loopback-connector-mongodb to use our instance of cls-bluebird without forking it.

[bajtos]

Issue moved to strongloop/loopback-context #21 via ZenHub