Help needed pinpointing and addressing a type error

[odd egret]

Hello,

When running the included code snippet

I am receiving the following error:

TS2322: Type
{ [x: string]: AggregationQuerySortDirection | undefined; }
is not assignable to type  Record<string, AggregationQuerySortDirection> 
 string  index signatures are incompatible.
Type  AggregationQuerySortDirection | undefined  is not assignable to type  AggregationQuerySortDirection 
Type  undefined  is not assignable to type  AggregationQuerySortDirection 
sortParams.ts(15, 3): The expected type comes from property  preparedKeys  which is declared here on type  SortParamsInput

(see attachment for a better formatted representation of the error message)

Could you help me understand what is causing it and how to fix it, please?

Thank you

[copper bane]

bovvshock#0

Playground Link

Preview:```ts
export type AggregationQuerySortDirection = -1 | 1

export type SortingFields = Record<
string,
AggregationQuerySortDirection

export type SortParamsInput = {
sortingFields: SortingFields
allowedFields: string[]
uniqueFields: string[]
index: number
addIdF
...```

You can choose specific lines to embed by selecting them before copying the link.

[odd egret]

@ashen hamlet ping

[twin dome]

@odd egret the issue is that sortingFields[key] is AggregationQuerySortDirection | undefined (at least when you enable noUncheckedIndexedAccess)

i'd probably refactor this, but it should give you an idea of how to approach things:

[copper bane]

mkantor#0

Playground Link

Preview:```ts
export type AggregationQuerySortDirection = -1 | 1

export type SortingFields = Record<
string,
AggregationQuerySortDirection

export type SortParamsInput = {
sortingFields: SortingFields
allowedFields: string[]
uniqueFields: string[]
index: number
addIdF
...```

You can choose specific lines to embed by selecting them before copying the link.

[odd egret]

I see, thank you. What do you mean by suggesting to refactor it?

[odd egret]

Btw, I was expecting that the key check against undefined would cover it? Because it seems like I am forced to check twice if key is not undefined? Once for the key itself and then once to be able to use it in sortingFields?

[twin dome]

you're not checking the key twice. you're checking the key once and then the value once. since you have noUncheckedIndexedAccess turned on, sortingFields[keyThatIsDefinitelyDefined] gives you back AggregationQuerySortDirection | undefined

here's a simpler example:

[copper bane]

mkantor#0

Playground Link

Preview:ts declare const x: Record<string, number> const y = x["a"] // ^?

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[twin dome]

y is number | undefined there. not because of anything related to the key ('a'), but y is accessed through x's index signature

[ashen hamlet]

The problem is that Typescript doesn't track the source of sortingFields[key] <- sortingFieldKeys <- Object.keys(sortingFields) and use that to narrow away the undefined

noUncheckedIndexedAccess is not really usable because of this.

I'd personally turn it off