LiveQuery pointer comparison does not handle null

[massimilianogalanti]

New Feature / Enhancement Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.

Current Limitation

Current QueryTools.js implementation protects itself from undefined objects but not from null objects. By using Parse Dashboard, it happens to create nulls instead of undefineds.

Feature / Enhancement Description

Checking for undefined and null.
((typeof obj !== 'undefined') && obj !== null)

Example Use Case

Register a livequery with a comparison on a pointer, then put that pointer to null (by code or by dashboard)

Alternatives / Workarounds

Use unset?

3rd Party References

[parse-github-assistant]

Thanks for opening this issue!

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[mtrezza]

Is this actually a bug?

[massimilianogalanti]

It is unclear to me if putting Pointers to null instead of undefining them is an acceptable practice in parse server. If it is, then probably not protecting against it is a bug.

[hariprasadiit]

Yes, I've also faced the same issue. setting pointer to a null value results in exception. If this null is not a valid value for pointers, it'd be helpful if we document it.

[massimilianogalanti]

Any news on this?

[mtrezza]

What is the exception being thrown?

[massimilianogalanti]

2|launch-parse  | TypeError: Cannot read properties of null (reading 'className')
2|launch-parse  |     at .../node_modules/parse-server/lib/LiveQuery/QueryTools.js:208:68
2|launch-parse  |     at equalObjectsGeneric (.../node_modules/parse-server/lib/LiveQuery/QueryTools.js:147:10)
2|launch-parse  |     at matchesKeyConstraints (.../node_modules/parse-server/lib/LiveQuery/QueryTools.js:207:14)
2|launch-parse  |     at matchesQuery (...//node_modules/parse-server/lib/LiveQuery/QueryTools.js:132:10)
2|launch-parse  |     at ParseLiveQueryServer._matchesSubscription (.../node_modules/parse-server/lib/LiveQuery/ParseLiveQueryServer.js:429:41)
2|launch-parse  |     at ParseLiveQueryServer._onAfterSave (.../node_modules/parse-server/lib/LiveQuery/ParseLiveQueryServer.js:236:50)
2|launch-parse  |     at messageRecieved (.../node_modules/parse-server/lib/LiveQuery/ParseLiveQueryServer.js:108:14)
2|launch-parse  |     at Subscriber.<anonymous> (.../node_modules/parse-server/lib/LiveQuery/ParseLiveQueryServer.js:115:60)
2|launch-parse  |     at Subscriber.emit (node:events:517:28)
2|launch-parse  |     at EventEmitter.handler (.../node_modules/parse-server/lib/Adapters/PubSub/EventEmitterPubSub.js:26:12)

[mtrezza]

Thanks, could you open a PR with a simple test that demonstrates the issue? There are existing LiveQuery tests in the /spec directory for guidance. Then you could just add the suggested fix in your first comment and we can fix the bug.