to-json-schema: Add option to provide input schema for effects

[bdashore3]

Hi there, I'm trying to move away from Zod to Valibot, but I've hit a snag when generating OpenAPI defintions.

My schemas heavily rely on transform operations for validation, but I'm getting an error that states Error: The "transform" action cannot be converted to JSON Schema.. This is highlighted in the docs and I understand why that's the case. However, there are ways around this that can be explored.

For example, the zod-openapi package gets around this by allowing the user to set effectType to "input" which takes the non-transformed defintion and builds the schema from there. It does this by default when new effects are provided (see: rhinobase/hono-openapi#3)

I'd suggest that valibot should do the same, or even does this by default if a transform operation is detected. That way, the JSON schema package becomes usable for almost any situation.

[bdashore3]

Also, using 'warn' when running toJsonSchema seems to ignore the failed actions and still produces a valid JSON schema. However, it may be good to look into warning by default on a transform.

[fabian-hiller]

What exactly does Zod's toJsonSchema function do when this option is enabled? I would guess it does exactly the same thing as our errorMode option when set to 'warn' or 'ignore'. Are you basically asking to introduce a new option to override/define errorMode specifically for transformations?