[Zod plugin] Allow code generation customization #2688
Description
Description
Summary
Proposes adding new settings to the @hey-api/zod plugin to allow greater customization of code generation.
Motivation
Currently, the only available option that influences code generation is dates, which provides very limited control. Adding new settings would allow:
- Ability to use other Zod functions, such as
codec. - Ability to refine constraints defined in OpenAPI, e.g.,
format: int32→z.int32(). - Ability to specify constraints based on OpenAPI Extensions.
These improvements would give developers more flexibility and precision when generating Zod schemas from OpenAPI specifications.
Proposed Solution
1. Add the schemaOverride Setting
schemaOverride is a function called in schemaTypeToZodSchema that allows developers to override the schemas generated by default.
2. Add the customSchemaBuilder Setting
customSchemaBuilder is a function called in the handler that allows creating reusable custom schemas. These can then be used in schemaOverride to avoid code duplication.
Proof of concept
In this fork, I crudely modified @hey-api/zod by adding Zod codecs to convert dates represented as strings into Dayjs objects.
The openapi-ts-sample example demonstrates how the received data is transformed using the created schemas.
Opportunities for Further Development
With Zod, the @hey-api/sdk plugin configuration could be extended to not only catch errors during type coercion but also return transformed data directly.
someSchema.decode(data)— for validating and transforming response bodies.someSchema.encode(data)— for preparing request payloads.
This enables reusing the same schema for both validation and data transformation, reducing code duplication and improving reliability.