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useSubscription and useObservableState cause duplicate requests

See original GitHub issue

When either hook is used in coordination with ajax.getJSON() (or similar observable), it acts as if 2 subscriptions are made as there are 2 XHR requests made for each hook.

Minimally reproducible example: https://codesandbox.io/s/quizzical-bassi-xcetk?file=/src/App.js

Monitor the network tab to see that 2 requests are made but only 1 state change is triggered. There are several “examples” in the one sandbox to demonstrate the issue.

When using a normal useEffect(() => stream$.subscribe()), everything works as expected.

Issue Analytics

State:
Created 3 years ago
Comments:5 (3 by maintainers)

Top GitHub Comments

1reaction

jeffmccormickcommented, Jun 11, 2020

Updated the sandbox to the alpha and everything looks great! Thank you!

1reaction

crimxcommented, Jun 4, 2020

Unfortunately this would be a breaking change as useEffect runs in commit phase. useMemo is intentionally used here so that synchronous values from observables can act as initial values. I think it would be best to do this after the React team releases more info about the concurrent mode.

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