feat: Add `exactOptional` struct by rekmarks · Pull Request #32 · MetaMask/superstruct

rekmarks · 2025-03-28T17:22:32Z

Adds a new struct exactOptional that enables strictly optional properties on object structs.

When used with object() structs, { foo: optional(x()) } results in { foo?: x | undefined }. This makes optional() incompatible with e.g. the Json type of @metamask/utils. Using exactOptional(x()), we instead get exactly optional properties i.e. { foo?: x }.

The name strictOptional was previously considered, however exactOptional is in line with the exactOptionalPropertyTypes TypeScript configuration option, whose effect we are trying to achieve.

This implementation is superior to the one currently in @metamask/utils in two ways:

The exactOptional struct and types should be forward-compatible with all versions of @metamask/superstruct.
By modifying the object struct in @metamask/superstruct, we avoid creating a second struct that supports exactOptional.

rekmarks · 2025-03-28T17:34:02Z

Already exists in the form of exactOptional() in @metamask/utils.

rekmarks · 2025-03-28T17:39:46Z

We may still want this.

rekmarks · 2025-03-28T18:03:09Z

src/utils.ts

I moved some stuff around in here but the only new thing is StrictOptionalize and its use in ObjectType.

src/struct.ts

test/typings/strictOptional.ts

src/struct.ts

src/structs/types.ts

src/struct.ts

FrederikBolding · 2025-03-31T09:44:44Z

Why do we wanna do this at the fork level instead of just using what already exists in @metamask/utils?

Adds a new struct `strictOptional` that enables strictly optional properties on `object` structs.

rekmarks · 2025-03-31T22:31:13Z

@FrederikBolding updated description per our discussion.

Mrtenz · 2025-04-01T08:20:24Z

src/struct.ts

+  Type = unknown,
+  Schema = unknown,
+> extends Struct<Type, Schema> {
+  // eslint-disable-next-line no-restricted-syntax


Can you add a comment to clarify why this is necessary?

Deprecates the local `exactOptional` implementation in favor of the one from `@metamask/superstruct@3.2.0`. See: MetaMask/superstruct#32

rekmarks requested a review from a team March 28, 2025 17:22

rekmarks changed the title ~~feat: Add strictOptional struct~~ feat: Add strictOptional struct Mar 28, 2025

rekmarks enabled auto-merge (squash) March 28, 2025 17:23

rekmarks disabled auto-merge March 28, 2025 17:23

rekmarks enabled auto-merge (squash) March 28, 2025 17:23

rekmarks force-pushed the rekm/strict-optional branch from 8982082 to 189f8e3 Compare March 28, 2025 17:24

rekmarks closed this Mar 28, 2025

auto-merge was automatically disabled March 28, 2025 17:34
Pull request was closed

rekmarks deleted the rekm/strict-optional branch March 28, 2025 17:34

rekmarks restored the rekm/strict-optional branch March 28, 2025 17:39

rekmarks reopened this Mar 28, 2025

rekmarks commented Mar 28, 2025

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src/utils.ts

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rekmarks Mar 28, 2025

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I moved some stuff around in here but the only new thing is StrictOptionalize and its use in ObjectType.