Typeseedcordv0.10.6

RequiredKeysOf

Extract all required keys from the given type.

This is useful when you want to create a new type that contains different type values for the required keys only or use the list of keys for validation purposes, etc...

type RequiredKeysOf<Type extends object> = Type extends unknown // For distributing `Type` ? Exclude<keyof Type, OptionalKeysOf<Type>> : never

type RequiredKeysOf<Type extends object> = Type extends unknown // For distributing `Type` ? Exclude<keyof Type, OptionalKeysOf<Type>> : never

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

declare function createValidation<
	Entity extends object,
	Key extends RequiredKeysOf<Entity> = RequiredKeysOf<Entity>,
>(field: Key, validator: (value: Entity[Key]) => boolean): (entity: Entity) => boolean;

type User = {
	name: string;
	surname: string;
	luckyNumber?: number;
};

const validator1 = createValidation<User>('name', value => value.length < 25);
const validator2 = createValidation<User>('surname', value => value.length < 25);

// @ts-expect-error
const validator3 = createValidation<User>('luckyNumber', value => value > 0);
// Error: Argument of type '"luckyNumber"' is not assignable to parameter of type '"name" | "surname"'.

 Utilities

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

declare function createValidation<
	Entity extends object,
	Key extends RequiredKeysOf<Entity> = RequiredKeysOf<Entity>,
>(field: Key, validator: (value: Entity[Key]) => boolean): (entity: Entity) => boolean;

type User = {
	name: string;
	surname: string;
	luckyNumber?: number;
};

const validator1 = createValidation<User>('name', value => value.length < 25);
const validator2 = createValidation<User>('surname', value => value.length < 25);

// @ts-expect-error
const validator3 = createValidation<User>('luckyNumber', value => value > 0);
// Error: Argument of type '"luckyNumber"' is not assignable to parameter of type '"name" | "surname"'.

 Utilities

Type

Type extends object

Type extends object

import type {RequiredKeysOf} from 'type-fest'; declare function createValidation< Entity extends object, Key extends RequiredKeysOf<Entity> = RequiredKeysOf<Entity>, >(field: Key, validator: (value: Entity[Key]) => boolean): (entity: Entity) => boolean; type User = { name: string; surname: string; luckyNumber?: number; }; const validator1 = createValidation<User>('name', value => value.length < 25); const validator2 = createValidation<User>('surname', value => value.length < 25); // @ts-expect-error const validator3 = createValidation<User>('luckyNumber', value => value > 0); // Error: Argument of type '"luckyNumber"' is not assignable to parameter of type '"name" | "surname"'. Utilities