Autocomplete expect string | string[]

[hortizgarrido]

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Steps to reproduce 🕹

No response

Current behavior 😯

Should not have to explicitly set the type in autocomplete

Expected behavior 🤔

Upgrading to latest MUI/material version is giving errors on how the autocomplete infers the type. I use to just be able to have <Autocomplete
.... />

but now i have to put <Autocomplete ...../>

Context 🔦

Issue affects entire code. Would need major rework.

Your environment 🌎

npx @mui/envinfo

  Don't forget to mention which browser you used.
  Output from `npx @mui/envinfo` goes here.

[huyle2405]

Same issue with the latest version.

Revert to version 5.10.15 will be ok.

[ZeeshanTamboli]

@hortizgarrido @huyle2405 Can you provide a CodeSandbox reproducing the issue or a minimal code example that reproduces the problem. The issue template is a good starting point.

[DaveITpl]

useAutocomplete.d.ts
export type AutocompleteValue<T, Multiple, DisableClearable, FreeSolo> = Multiple extends true

default property is false

[gnowland]

This bug was introduced by #35275. Since that PR was merged omitting Autocomplete parameter multiple results in TypeScript inferring that the multiple parameter is true when it should be false by default (according to the API docs).

Until this bug is fixed you can fix the error by explicitly setting multiple={false} on all Autocomplete components.

[fenghan34]

The default type of multiple prop is undefined if you don’t specify it, which can be found by hovering on <Autocomplete ... /> or checking type declarations in source code.

The PR #35275 I made was to fix the incorrect inferring type of AutocompleteValue when multiple is true, which worked as expected and passed all typescript tests. And the inferred type should be NonNullable<T | AutocompleteFreeSoloValueMapping<FreeSolo>> or T | null | AutocompleteFreeSoloValueMapping<FreeSolo> if Multiple is undefined(default) or false as follows.

export type AutocompleteValue<T, Multiple, DisableClearable, FreeSolo> = Multiple extends true
  ? Array<T | AutocompleteFreeSoloValueMapping<FreeSolo>>
  : DisableClearable extends true
  ? NonNullable<T | AutocompleteFreeSoloValueMapping<FreeSolo>>
  : T | null | AutocompleteFreeSoloValueMapping<FreeSolo>;

Please educate me if I misunderstand somewhere. And I still can’t reproduce this problem locally, so It would be very helpful to debug it if someone could provide the code example and environment reproducing the problem.

[gnowland]

@fenghan34 I've replicated the issue affecting #35275 in a CodeSandbox: https://codesandbox.io/s/bold-thunder-h6zyo2.

The props I included in the example are value and onChange because these are the props that were affected by this bug in my codebase, but there may be other props of the Autocomplete component that would also cause this error that I'm unaware of.

[fenghan34]

@gnowland Thanks!

It turns out the AutocompleteValue type would be inferred to T[] if you disable strictNullChecks in your project since TypeScript would ignore undefined and allow it to extend any type except never. Here's the demonstration.

And It hasn't been detected in TypeScript tests as strictNullChecks is enabled in MUI codebase. I'm not sure if need to improve the TypeScript test workflow, and I've made a PR to fix this issue.

[gnowland]

Thanks for explaining!! I’m still a bit befuddled by complex TypeScript declarations, glad I could help define the issue for you to fix :)