You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
36 lines
1.3 KiB
36 lines
1.3 KiB
// TODO: Remove this when we target TypeScript >=3.5. |
|
// eslint-disable-next-line @typescript-eslint/generic-type-naming |
|
type _Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>; |
|
|
|
/** |
|
Create a type that requires exactly one of the given keys and disallows more. The remaining keys are kept as is. |
|
|
|
Use-cases: |
|
- Creating interfaces for components that only need one of the keys to display properly. |
|
- Declaring generic keys in a single place for a single use-case that gets narrowed down via `RequireExactlyOne`. |
|
|
|
The caveat with `RequireExactlyOne` is that TypeScript doesn't always know at compile time every key that will exist at runtime. Therefore `RequireExactlyOne` can't do anything to prevent extra keys it doesn't know about. |
|
|
|
@example |
|
``` |
|
import {RequireExactlyOne} from 'type-fest'; |
|
|
|
type Responder = { |
|
text: () => string; |
|
json: () => string; |
|
secure: boolean; |
|
}; |
|
|
|
const responder: RequireExactlyOne<Responder, 'text' | 'json'> = { |
|
// Adding a `text` key here would cause a compile error. |
|
|
|
json: () => '{"message": "ok"}', |
|
secure: true |
|
}; |
|
``` |
|
*/ |
|
export type RequireExactlyOne<ObjectType, KeysType extends keyof ObjectType = keyof ObjectType> = |
|
{[Key in KeysType]: ( |
|
Required<Pick<ObjectType, Key>> & |
|
Partial<Record<Exclude<KeysType, Key>, never>> |
|
)}[KeysType] & _Omit<ObjectType, KeysType>;
|
|
|