Type Alias SetNonNullable<BaseType, Keys>

SetNonNullable: {
    [Key in keyof BaseType]: Key extends Keys
        ? NonNullable<BaseType[Key]>
        : BaseType[Key]
}

Create a type that makes the given keys non-nullable, where the remaining keys are kept as is.

If no keys are given, all keys will be made non-nullable.

Use-case: You want to define a single model where the only thing that changes is whether or not some or all of the keys are non-nullable.

Type Parameters

import type {SetNonNullable} from 'type-fest';

type Foo = {
a: number | null;
b: string | undefined;
c?: boolean | null;
}

type SomeNonNullable = SetNonNullable<Foo, 'b' | 'c'>;
// type SomeNonNullable = {
// a: number | null;
// b: string; // Can no longer be undefined.
// c?: boolean; // Can no longer be null, but is still optional.
// }

type AllNonNullable = SetNonNullable<Foo>;
// type AllNonNullable = {
// a: number; // Can no longer be null.
// b: string; // Can no longer be undefined.
// c?: boolean; // Can no longer be null, but is still optional.
// }