0.86.6: Generated `transformers.gen.ts` references missing transformer functions

[nghiepdev]

Description

Since @hey-api/openapi-ts@0.86.6, the generated client file transformers.gen.ts references response transformer functions that are not emitted or imported, causing TypeScript errors.

Example generated code:

// This file is auto-generated by @hey-api/openapi-ts

import type {
  ChatControllerCreateResponse,
  MetaControllerFindAllResponse,
} from "./types.gen";

export const chatControllerCreateResponseTransformer = async (
  data: any,
): Promise<ChatControllerCreateResponse> => {
  data = chatResponseDtoSchemaResponseTransformer(data);
  return data;
};

export const metaControllerFindAllResponseTransformer = async (
  data: any,
): Promise<MetaControllerFindAllResponse> => {
  data = paginatedResponseDtoSchemaResponseTransformer(data);
  return data;
};

generated/client/transformers.gen.ts:11:10 - error TS2304: Cannot find name >'chatResponseDtoSchemaResponseTransformer'.
generated/client/transformers.gen.ts:18:10 - error TS2304: Cannot find name >'paginatedResponseDtoSchemaResponseTransformer'.

Reproducible example or configuration

No response

OpenAPI specification (optional)

No response

System information (optional)

@hey-api/openapi-ts@0.86.6 and @hey-api/openapi-ts@0.86.7

[dosubot]

This happens because, starting with v0.60.0, transformer functions are only generated if you add @hey-api/transformers to your plugins and set transformer: true in your @hey-api/sdk plugin config. Without these, the referenced transformer functions (like chatResponseDtoSchemaResponseTransformer) won't be emitted, causing TypeScript errors. To fix this, update your config as shown in the migration guide:

export default {
  plugins: [
    { name: '@hey-api/transformers' },
    { name: '@hey-api/sdk', transformer: true },
    // ...other plugins
  ],
  // ...other config
};

Also, note that transformers.gen.ts is no longer re-exported from index.ts, so you should import transformers directly from transformers.gen.ts (details). For more on how transformers work and their limitations, see the transformers docs.

To reply, just mention @dosu.

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[nghiepdev]

I set transformer: true for every plugin, but the issue persists.

[dosubot]

The most common cause for missing transformer functions is plugin misconfiguration. You need to add @hey-api/transformers to your plugins array and set transformer: true only in the @hey-api/sdk plugin—not every plugin. For example:

export default {
  plugins: [
    { name: '@hey-api/transformers' },
    { name: '@hey-api/sdk', transformer: true },
    // ...other plugins
  ],
  // ...other config
};

Also, transformers are only generated for response schemas defined via $ref in your OpenAPI spec; union types and error responses are not supported for transformation. If your responses aren't using $ref, transformer functions won't be generated even with the correct config. More details are in the migration guide and transformers docs.

If you still see missing functions after verifying these, check your codegen logs for warnings, and consider sharing your config and a sample of your OpenAPI spec for deeper troubleshooting.

To reply, just mention @dosu.

---

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[nghiepdev]

I enabled transformer: true for the @hey-api/sdk plugin, but the issue remains.

[dosubot]

If transformer functions are still missing, double-check that your plugins array includes both @hey-api/transformers and { name: '@hey-api/sdk', transformer: true }—this is required for generation, not just enabling the transformer option in the SDK plugin alone. Also, transformers are only generated for response schemas defined via $ref in your OpenAPI spec; union types and error responses are not supported for transformation, so if your responses aren't using $ref, transformer functions won't be emitted even with the correct config.

If you’ve confirmed your config matches the docs and the issue persists, please share your full codegen config and a sample of your OpenAPI spec for the affected endpoints. Also, check your codegen logs for any warnings about transformer generation. More details are in the migration guide and transformers docs.

To reply, just mention @dosu.

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[mrlubos]

I'm going to assume this is a regression, can you provide an OpenAPI spec to reproduce?

[mrlubos]

@dosu stop annoying the man

[dosubot]

Understood. I'll pause further replies here unless asked.

To reply, just mention @dosu.

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[nghiepdev]

@mrlubos Here's an OpenAPI spec that reproduces the issue: link

[htndev]

I came here to say that I'm also running into that issue.
It has started happening to me since v0.86.6. It's ok on v0.86.5.
Here is my contract: [link]