"Error: Callback was already called" when using "near" filter

[bachirelkhoury]

Given this simple geolocation query, when I include the "near" query I'm getting this error:

/node_modules/mongodb/lib/utils.js:98
    process.nextTick(function() { throw err; });
                                  ^

Error: Callback was already called.
    at /node_modules/async/dist/async.js:844:36
    at /node_modules/async/dist/async.js:3676:17
    at /node_modules/async/dist/async.js:339:31
    at /node_modules/strong-remoting/lib/remote-objects.js:694:7
    at execStack (/node_modules/strong-remoting/lib/remote-objects.js:490:9)
    at RemoteObjects.execHooks (/node_modules/strong-remoting/lib/remote-objects.js:497:10)
    at interceptInvocationErrors (/node_modules/strong-remoting/lib/remote-objects.js:693:10)
    at /node_modules/loopback-phase/node_modules/async/lib/async.js:148:21
    at /node_modules/loopback-phase/node_modules/async/lib/async.js:148:21
    at /node_modules/loopback-phase/node_modules/async/lib/async.js:148:21

Can't find the root cause of this.

This code works:

user.find({}, function(err, users) {
        if (err) {
          return cb(err);
        }
        return cb(null, users);
    });
  };

This one below throws the error. I've placed a breakpoint in the callback, and it does get called twice internally. Couldn't trace it too far so not sure what's firing this.

user.find({
      where: {
        location: {near: here, maxDistance: distance, unit: 'meters'}
      }
    }, function(err, users) {
        if (err) {
          return cb(err);
        }
        return cb(null, users);
    });
  };

[rptally]

I had another version of the server code running on a different machine that wasn't showing the problem. The only dependency I changed to correct the issue was the loopback-datasource-juggler version back from 51 to 50 to 49. The loopback-connector-mongodb performs the query correctly with loopback-datasource-juggler 2.49.0. My speculation is a breaking change occurred in 2.50.0.

This is the dependencies section from the project package.json

"dependencies": {
  "compression": "^1.6.2",
  "cors": "^2.8.1",
  "helmet": "^1.3.0",
  "loopback": "^2.34.1",
  "loopback-boot": "^2.22.0",
  "loopback-component-explorer": "^2.6.0",
  "loopback-component-storage": "^1.9.1",
  "loopback-connector-mongodb": "^1.15.2",
  "loopback-connector-sparkpost": "0.0.2",
  "loopback-datasource-juggler": "~2.49.0",
  "serve-favicon": "^2.3.0",
  "strong-error-handler": "^1.1.0",
  "twilio": "^2.11.0"
},

[Amir-61]

@rptally @bachirelkhoury it seems this is a regression from a recent work. Could @rptally or @bachirelkhoury please provide a sample repo using our loopback-sandbox so I can reproduce it on my local machine and then label it as a bug and escalate it?

I suspect this is a regression from a recent community PR#259; @superkhau since you reviewed that PR, you may have a better insight.

[rptally]

It's very easy to duplicate. Create a loopback app; add a mongo datasource; create a model (Store) with a geopoint field called loc; start the server. Then use the browser to run the query:

http://localhost:3000/api/stores?filter[where][loc][near]=32.0,-92.0

You immediately get the "Error: Callback was already called." error.

I've attached the project as requested. Please let me know what else you need.

fred.zip

[superkhau]

@Amir-61 Thanks for verifying the bug. Let's escalate/TOB/major it.

[superkhau]

@rptally What node version are you on?

[superkhau]

As for the regression, that part is not for sure yet. @loay Is looking into a similiar failure to confirm and see if a related issue will fix this too. @loay Please comment here when that happens.