Fix IDBKeyVal get returning undefined instead of null

[janicduplessis]

Details

getItem is supposed to return null when the value doesn't exist in storage. This is what the native sqlite storage implementation does, as well as what the function documentation says. However https://github.com/jakearchibald/idb-keyval#get returns undefined when the value doesn't exist so we need to convert it to null.

This caused some issues where some components would stay stuck in loading state because in onyx we assume undefined means the key value has not been loaded from storage, non-existing keys are represented by null. The issue was reported here Expensify/App#29169 (comment).

Related Issues

Expensify/App#29169

Automated Tests

N/A

Manual Tests

Tested in Expensify app with Expensify/App#29169. On web, opening settings will cause a blank screen to open. After this fix it loads properly.

Author Checklist

• I linked the correct issue in the ### Related Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
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  • I verified that any callback methods that were added or modified are named for what the method does and never what callback they handle (i.e. toggleReport and not onIconClick)
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• I verified any variables that can be defined as constants (ie. in CONST.js or at the top of the file that uses the constant) are defined as such
• I verified that if a function's arguments changed that all usages have also been updated correctly
• If a new component is created I verified that:
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  • All props are defined accurately and each prop has a /** comment above it */
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  • The only data being stored in the state is data necessary for rendering and nothing else
  • If we are not using the full Onyx data that we loaded, I've added the proper selector in order to ensure the component only re-renders when the data it is using changes
  • For Class Components, any internal methods passed to components event handlers are bound to this properly so there are no scoping issues (i.e. for onClick={this.submit} the method this.submit should be bound to this in the constructor)
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Screenshots/Videos

Web

Mobile Web - Chrome

Before:

After:

Mobile Web - Safari

Desktop

iOS

Android

[tgolen]

According to your explanation, shouldn't this check if the value is undefined, and if so, return null? This change looks like the ternary isn't doing anything and is the same thing as returning the value.

[janicduplessis]

This will check for null / undefined double = and return null in both cases, I could change the check to === undefined if you think it is clearer.

[mountiny]

Good shout, I think given the explanation and RCA, checking for === undefined would be cleaner

[tgolen]

Yes please. Our styles prefer strict comparison. Could you also please add a comment to the code that the purpose for this logic is to make the storage APIs consistent?

[janicduplessis]

Updated

[jjcoffee]

I'm getting some unexpected report preview loading behaviour when testing this PR (but probably stemming from #401), as well as the RHP generally rendering less snappily:

chrome-desktop-2023-10-30_12.23.39.mp4

Note that the IOU preview and header aren't rendering at the same time. Compare with v1.0.107:

chrome-desktop-2023-10-30_12.57.20.mp4

[janicduplessis]

@jjcoffee Do you know if this happens only on this PR and not on main? Or is it a regression since 1.0.107?

[jjcoffee]

It looks like a regression since 1.0.107.

[janicduplessis]

👍 I think we can go ahead with this then, I can have a look at that issue tomorrow. @tgolen any idea what could have caused that?

[jjcoffee]

I've tested against #401 with this fix added and I'm not seeing the same issue, so must be unrelated!

[tgolen]

Sorry! I don't have any ideas what can be causing that, but it sounds like we are OK to merge this.

[marcaaron]

LGTM

[tgolen]

@mountiny would you approve and merge this, please?

[mountiny]

Thanks for digging into this!

[janicduplessis]

I can confirm the regression @jjcoffee found is related to #401, looking at what is going on exactly now.