unresolved get cause onValue to not be called on child path

[christophe-g]

Describe your environment

• Operating System version: linux
• Browser version: chrome latest
• Firebase SDK version: JS SDK v9.8.4
• Firebase Product:

Describe the problem

onValue callback function on node for which a get on a parent has not yet resoved will never be called. This is pretty bad as get seems to have unpredictable side-effect.

get should not have ANY side-effect.

Possibly related to #6038. Took me ages to identify the reason for some part of my app failing while transitionning to v9.

Work around for now: avoid any use of get, replace by a thenable onValue ... {onlyOnce: true}

Steps to reproduce:

go there - possibly adjust the ms property

The test case is fragile as it depends on race conditions. So please adjust the ms wait property to see the test fail.

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[christophe-g]

Any news on this?

Can you reproduce the faulty behavior ?

[christophe-g]

This still happens under 9.9.1

[maneesht]

@christophe-g I was able to reproduce the issue. I am looking into it.

[maneesht]

@christophe-g we were able to reproduce this with once as well. Can you provide an example where the correct behavior is observed with once?

[nauzilus]

Thanks for looking into this @maneesht . Not sure if you still need examples, but I have consistently repeatable demos in stackblitz showing the change in behaviour between 9.8.3, 9.8.4, and 9.8.4 with the workaround mentioned:

• 9.8.3
• 9.8.4
• 9.8.4 with workaround

The defect is triggered when there's a get and an onValue after the connection has already been established, so there's a dummy query just to get firebase connected before rendering the test component. 9.8.3 the once and live values both populate but in 9.8.4 only once is populated.

[maneesht]

@nauzilus - thanks for the thorough examples. We were able to create a test case to prevent this from happening again. The fix should be in soon.