35 lines
1 KiB
TypeScript
Executable file
35 lines
1 KiB
TypeScript
Executable file
import {Except} from './except';
|
|
|
|
/**
|
|
Create a type that makes the given keys optional. The remaining keys are kept as is. The sister of the `SetRequired` type.
|
|
|
|
Use-case: You want to define a single model where the only thing that changes is whether or not some of the keys are optional.
|
|
|
|
@example
|
|
```
|
|
import {SetOptional} from 'type-fest';
|
|
|
|
type Foo = {
|
|
a: number;
|
|
b?: string;
|
|
c: boolean;
|
|
}
|
|
|
|
type SomeOptional = SetOptional<Foo, 'b' | 'c'>;
|
|
// type SomeOptional = {
|
|
// a: number;
|
|
// b?: string; // Was already optional and still is.
|
|
// c?: boolean; // Is now optional.
|
|
// }
|
|
```
|
|
*/
|
|
export type SetOptional<BaseType, Keys extends keyof BaseType = keyof BaseType> =
|
|
// Pick just the keys that are not optional from the base type.
|
|
Except<BaseType, Keys> &
|
|
// Pick the keys that should be optional from the base type and make them optional.
|
|
Partial<Pick<BaseType, Keys>> extends
|
|
// If `InferredType` extends the previous, then for each key, use the inferred type key.
|
|
infer InferredType
|
|
? {[KeyType in keyof InferredType]: InferredType[KeyType]}
|
|
: never;
|