Running LiveQuery with matchesQuery returns no results.

[danibjor]

Issue Description

Running LiveQuery with matchesQuery returns no results - if the same Query is executed with find( .. ), results are returned.

Steps to reproduce

    var d = new Date();
    var time = (1 * 12 * 60 * 60 * 1000);
    var expirationDate = new Date(d.getTime() - (time));

    var query = new Parse.Query('Radio');
    var innerQuery = new Parse.Query('RadioLocation');

    innerQuery.greaterThanOrEqualTo("gpsDate", expirationDate);
    query.matchesQuery("latestLocation", innerQuery);

    console.log('subscribing for locations', expirationDate);

    var subscription = query.subscribe();

Running the query in Chrome console (chrome dev tools)

var d = new Date();
    var time = (1 * 12 * 60 * 60 * 1000);
    var expirationDate = new Date(d.getTime() - (time));

    var query = new Parse.Query('Radio');
    var innerQuery = new Parse.Query('RadioLocation');

    innerQuery.greaterThanOrEqualTo("gpsDate", expirationDate);
    query.matchesQuery("latestLocation", innerQuery);

query.find({
  success: function(res) {
    console.log("res", res.length, res);
  }
});

returns

ParsePromise {_resolved: false, _rejected: false, _resolvedCallbacks: Array[0], _rejectedCallbacks: Array[0]}
VM4688:13 
(string) res 
(int) 12 
(array) [ParseObject, ParseObject, ParseObject, ParseObject, ParseObject, ParseObject, ParseObject, ParseObject, ParseObject, ParseObject, ParseObject, ParseObject]

So, the query returns expected results when .find() is executed - but no events when using LiveQuery. If I remove the innerQuery and filter on Radio.UpdatedAt, events are fired - so LiveQuery are working.

Expected Results

Events triggered when RadioLocation gets new items

Actual Outcome

No events gets triggered

Environment Setup

• Server
  • parse-server version 2.2.23
  • Operating System: docker container
  • Hardware: Running in Ubuntu 14.4 container, in VirtualBox, on iMac OSX v.Latest
  • Localhost or remote server? Dev setup
• Database
  • MongoDB version: Running docker cluster, v3.2
  • Hardware: Same docker swarm as above
  • Localhost or remote server? Same as above

[danibjor]

So, I guess relation queries are not supported on subscribe/liveQuery?

[flovilmart]

It seems that it's not supported yet. Do you want to try to add that support?

[danibjor]

I still don't speak fluent Parse, but I could give it a go.

[flovilmart]

Awesome! Excited to see that one land!

[dpoetzsch]

@danibjor I just stumbled over the same problem, how's your progress on supporting this feature?

[danibjor]

@dpoetzsch Not too good - need to find time to better understand everything that is involved, so I don't break anything..

[dpoetzsch]

So I investigated a bit today. I would guess that basically we would have to add a case in the switch statement in QueryTools.js, line 279 for $inQuery. The problem is that we would have to execute the query in this case making the whole thing asynchronous. Also the overhead seems to be significant: For each change in the table we would need to execute a query.

Any ideas maybe on how to make this more efficient?

[flovilmart]

The overhead is effectively significant. But that probably can be logged as a warning when subscribing to that kind of query. Moreover if the secondary table is improperly indexed.
After all, as a developer, you can probably work around that performance hit by optimizing the data relationship right?

[flovilmart]

Also, you can use async/await to check the query match in that case, as babel will transpile to yield that should be supported in node 4.5

[flovilmart]

I'll give it a try with async/await and the additional required read..

[malhal]

Subscribe to RadioLocation instead, where the Radio ID is in an array of IDs.

[flovilmart]

Closing due to lack of activity, please update to latest parse-server version and open a new issue if the issue persist.

Also, for now, LiveQuery don't support complex queries that would require additional access to the database.

[Edijae]

Any plan to support parselivequery on parserelation?

[RaveKev]

Would love to see that feature

[facuparedes]

Wow, 4 years and they don't added requested feature. Nice.

[dblythy]

@FNPCMDs I will give this a crack, be mindful parse is a community based project that requires contributions from people who need features for their own projects. You’re welcome to submit a PR or join discussions on the community forum, but please be respectful.