René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"pattern validation for optional fields","articleBody":"### Which @angular/* package(s) are relevant/related to the feature request?\n\nforms\n\n### Description\n\noptional fields can be represented by\n\n```ts\nfoo: string | null;\n```\n\nthe pattern signature is the following and we get a ts(2345) error.\n\n```ts\nexport function pattern\u003cTPathKind extends PathKind = PathKind.Root\u003e(\n  path: SchemaPath\u003cstring, SchemaPathRules.Supported, TPathKind\u003e,\n  pattern: RegExp | LogicFn\u003cstring | undefined, RegExp | undefined, TPathKind\u003e,\n  config?: BaseValidatorConfig\u003cstring, TPathKind\u003e,\n) {\n```\n\n### Proposed solution\n\n```ts\nexport function pattern\u003cTPathKind extends PathKind = PathKind.Root\u003e(\n  path: SchemaPath\u003cstring | null, SchemaPathRules.Supported, TPathKind\u003e,\n  pattern: RegExp | LogicFn\u003cstring | null | undefined, RegExp | undefined, TPathKind\u003e,\n  config?: BaseValidatorConfig\u003cstring | null, TPathKind\u003e,\n) {\n```\n\n```ts\nexport function pattern\u003cTValue extends string | null, TPathKind extends PathKind = PathKind.Root\u003e(\n  path: SchemaPath\u003cTValue , SchemaPathRules.Supported, TPathKind\u003e,\n  pattern: RegExp | LogicFn\u003cTValue  | undefined, RegExp | undefined, TPathKind\u003e,\n  config?: BaseValidatorConfig\u003cTValue , TPathKind\u003e,\n) {\n```\n\n### Alternatives considered\n\nAlternative is to just have it as string and use `''`","author":{"url":"https://github.com/cheng93","@type":"Person","name":"cheng93"},"datePublished":"2026-01-14T10:17:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/66539/angular/issues/66539"}