AllOrNone TypeAlias

A type modifier that constrains the keys of T to be either all present (with their declared types) or all absent. Mixed shapes — supplying some keys but not others — are rejected at compile time.

Use this to express "supply this whole group, or supply none of it" without having to police the constraint at runtime.

This API is provided for existing users, but is not recommended for new users.

To use, import via @fluidframework/core-interfaces/legacy.

For more information about our API support guarantees, see here.

Signature

export type AllOrNone<T> = T | {
    [K in keyof T]?: never;
};

Type Parameters

Parameter	Description
T

Remarks

The "all-or-none" shape is a small, general, composable primitive — it shows up wherever a feature is wired up by supplying a group of cooperating objects (driver triples, transport plus credentials, etc.) and is awkward to spell out inline. Naming it lets callers reuse the same pattern and lets reviewers see the intent at the declaration site instead of re-deriving it from a hand-rolled discriminated union. The mapped form { [K in keyof T]?: never } is mechanical, so downstream consumers do not need any unusual TS feature to use it.

Example

interface Auth { user: string; token: string }
type Props = { url: string } & AllOrNone<Auth>;
const a: Props = { url: "x" };                                    // ok
const b: Props = { url: "x", user: "u", token: "t" };             // ok
const c: Props = { url: "x", user: "u" };                         // error