[QUESTION] Custom response format for validation error

How can I reformat default response for validation errors? I find the default formatting too verbose for my app, and wanted to return errors in different structure.

I thought of adding error handler explicitly for pydantic.ValidationError but this is ignored as the error is caught before that and handled internally by FastAPI:

https://github.com/tiangolo/fastapi/blob/4a1648b04e74b5943f3ffadf92737f7d9c8201af/fastapi/routing.py#L68-L72

Is this possible to override default formatter and handle ValidationError on my own? I tried to search through issues and docs but couldn’t find anything related.

[Olegt0rr]

This is supported now in the latest versions. 🎉

You can now add handlers for RequestValidationError and get the full Pydantic ValidationError: https://fastapi.tiangolo.com/tutorial/handling-errors/#override-request-validation-exceptions

Make sure to update your FastAPI version. The current latest is 0.27.0.

I’ll close this issue now, but feel free to add more comments or create new issues.

Docs builders don’t know about exception overriding. Please add an example this page.

Screenshot

@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request, exc):
    return PlainTextResponse(str(exc), status_code=422)

[tiangolo]

This is supported now in the latest versions. 🎉

You can now add handlers for RequestValidationError and get the full Pydantic ValidationError: https://fastapi.tiangolo.com/tutorial/handling-errors/#override-request-validation-exceptions

Make sure to update your FastAPI version. The current latest is 0.27.0.

I’ll close this issue now, but feel free to add more comments or create new issues.