Support x-pattern-message extension for regular expressions #4116

Activity

1. michaelboyles

   added

   feature 🚀Feature request.Feature request.

   on Jun 21, 2026
2. pullfrog commented on Jun 21, 2026

   

   pullfrogBot

   on Jun 21, 2026 – with Pullfrog

   Last edited by pullfrog

   Contributor

   More actions

   Plan: Support x-pattern-message extension for regular expressions

   Background

   The x-pattern-message extension (popularized by openapi-generator) provides a human-readable description alongside a regex pattern constraint on string schemas. It passes a custom error message to validator .regex() calls.

   Current state: The OpenAPI parsers already copy all x-* extensions to the IR schema objects via parseExtensions(), so x-pattern-message is already accessible at codegen time — but no plugin reads it. The Zod and Valibot patternNode functions only emit the regex literal without a message argument.

   Changes by File

   1. Zod v3 — packages/openapi-ts/src/plugins/zod/v3/toAst/string.ts

   patternNode (line 67): Read ctx.schema['x-pattern-message'] and pass as second arg to .regex():

   function patternNode(ctx: StringResolverContext): ChainResult {
     const { chain, schema } = ctx;
     if (!schema.pattern) return;
     const flags = /\\[pP]\{/.test(schema.pattern) ? 'u' : undefined;
     const message = schema['x-pattern-message'];
     return chain.current.attr(identifiers.regex).call(
       $.regexp(schema.pattern, flags),
       ...(message ? [$.literal(message as string)] : [])
     );
   }

   2. Zod v4 — packages/openapi-ts/src/plugins/zod/v4/toAst/string.ts

   Same change as v3 in patternNode (line 74).

   3. Zod mini — packages/openapi-ts/src/plugins/zod/mini/toAst/string.ts

   patternNode (line 77): Same approach. Note: mini wraps pattern in .check(), but the .regex() call itself still supports a message second arg.

   4. Valibot — packages/openapi-ts/src/plugins/valibot/v1/toAst/string.ts

   patternNode (line 67): Valibot's regex() action accepts (input, error) where error is a string message:

   function patternNode(ctx: StringResolverContext): PipeResult {
     const { schema } = ctx;
     const { v } = ctx.plugin.imports;
     if (!schema.pattern) return;
     const flags = /\\[pP]\{/.test(schema.pattern) ? 'u' : undefined;
     const message = schema['x-pattern-message'];
     return $(v).attr(identifiers.actions.regex).call(
       $.regexp(schema.pattern, flags),
       ...(message ? [$.literal(message as string)] : [])
     );
   }

   5. Test fixture update

   Add x-pattern-message to an existing pattern-bearing schema in specs/3.0.x/validators.json (e.g., the ^\d{3}-\d{2}-\d{4}$ pattern at line 14) and regenerate snapshots via pnpm tu.

   6. Schemas plugin — packages/openapi-ts/src/plugins/@hey-api/schemas/plugin.ts

   Optionally add x-pattern-message to the stripSchema delete list for form mode — though x-pattern-message is a valid custom extension in JSON Schema output, so this may not be needed.

   What does NOT need changes

   • Parsers: parseExtensions() already copies all x-* keys to IR. No parser changes needed.
   • IR types: IRSchemaObject already extends SpecExtensions. No type changes needed.
   • TypeScript plugin: Correctly ignores pattern (TypeScript has no regex types).
   • Arktype: No arktype plugin exists in this repo — out of scope.

   Validation

   After changes: run pnpm tu -- @hey-api/openapi-ts-tests to update snapshots, then pnpm typecheck and pnpm test.

   Task list (4/4 completed)

   • Analyze the issue and gather context (read comments, events, learnings file)
   • Explore codebase: understand how validator plugins handle pattern/regex
   • Explore codebase: check for arktype plugin and schemas plugin extension stripping
   • Produce structured plan and report progress

     ^{｜ Implement plan ➔ ｜ View workflow run ｜ via Pullfrog ｜ Using DeepSeek Pro (free via Pullfrog for OSS) ｜ 𝕏}
3. mrlubos commented on Jun 21, 2026

   

   mrlubos

   on Jun 21, 2026

   Member

   More actions

   Should be easy enough, let's get it in

   👍React with 👍1Reacted by Michael
4. pullfrog commented on Jun 21, 2026

   

   pullfrogBot

   on Jun 21, 2026 – with Pullfrog

   Last edited by pullfrog

   Contributor

   More actions

   Implemented x-pattern-message support across all 4 validator plugins (Zod v3, Zod v4, Zod mini, Valibot). When a string schema has x-pattern-message, it's passed as the second arg to .regex() / v.regex(). Added test fixture coverage and updated 7 snapshots. Typecheck passes clean.

   PR: #4117

   Task list (10/10 completed)

   • Read relevant source files (Zod v3, Zod v4, Zod mini, Valibot patternNode functions)
   • Create branch for changes
   • Update Zod v3 patternNode to support x-pattern-message
   • Update Zod v4 patternNode to support x-pattern-message
   • Update Zod mini patternNode to support x-pattern-message
   • Update Valibot patternNode to support x-pattern-message
   • Add x-pattern-message to test fixture in specs/3.0.x/validators.json
   • Run snapshot update (pnpm tu -- @hey-api/openapi-ts-tests)
   • Run typecheck and tests
   • Commit, push, create PR

     ^{｜ View workflow run ｜ via Pullfrog ｜ Using DeepSeek Pro (free via Pullfrog for OSS) ｜ 𝕏}
5. mrlubos

   closed this as completedin #4117on Jun 21, 2026
6. mrlubos commented on Jun 21, 2026

   

   mrlubos

   on Jun 21, 2026

   Member

   More actions

   This will be available in the next release or you can get it now with npm i @hey-api/openapi-ts@next