Override 422 UnprocessableEntity response

[atistler]

Currently pydantic validation errors are rendered something like this:

422 UnprocessableEntity

[
	{
		"loc": [
			"job_type"
		],
		"msg": "field required",
		"type": "value_error.missing"
	},
	{
		"loc": [
			"details",
			"action"
		],
		"msg": "field required",
		"type": "value_error.missing"
	},
	{
		"loc": [
			"details",
			"options"
		],
		"msg": "field required",
		"type": "value_error.missing"
	}
]

Is there anyway to override this behavior and make the response body customizable specifically for 422's when the body is invalid.

[atistler]

I tried to specify a "422" in the response but that does not seem to make a difference:

        @self.app.post(
            "/v2/jobs",
            summary="Create job",
            operation_id="createJob",
            description="Creates a job",
            responses={"201": response.Job, "403": response.UnauthorizedError, "422": response.UnprocessableEntityError, "409": response.ConflictError},
            tags=[jobs_tag],
        )
        def create_job(body: CreateJobBody):

[luolingchun]

@atistler Why you need override response 422？Can you write a simple demo.

Pydantic validation errors will be raised when validate pydantic model, refer to https://github.com/luolingchun/flask-openapi3/blob/master/flask_openapi3/request.py#L134-L134

[atistler]

Because all other http errors in my application are structured in the following way:

{
   code: str,
   message: str
}

I would like to maintain that consistency. I guess i could write a decorator wrapping the app.post() that catches the pydantic validation error. I would seem that flask-openapi3 shouldn't make assumptions about how the 422 should be rendered as an http response though.

[luolingchun]

We have drafted a PR (Be able to change 422 validation errors to other http response status code) to discuss the 422 UnprocessableEntity response, So we can merge and solve this problem.

My idea is to add validation_error_status, validation_error_model, validation_error_callback to OpenAPI:

• validation_error_status: the status code of the response
• validation_error_model: response model for OpenAPI Specification
• validation_error_callback: response callback, the return format corresponds to the validation_error_model

from pydantic import ValidationError, BaseModel


class ValidationErrorModel(BaseModel):
     code: str,
     message: str

def validation_error_callback(e: ValidationError):
    validation_error_object = ValidationErrorModel(code="400", mmessage=e.json())
    response = make_response(validation_error_object.json())
    response.headers["Content-Type"] = "application/json"
    response.status_code = getattr(current_app, "validation_error_status", 422)
    return response


app = OpenAPI(__name__, validation_error_status=422, validation_error_model=ValidationErrorModel, validation_error_callback=validation_error_callback)

And then change the logic of request.

try:
    # Validate header, cookie, path, and query parameters
    if header:
        _do_header(header, func_kwargs)
    if cookie:
        _do_cookie(cookie, func_kwargs)
    if path:
        _do_path(path, path_kwargs, func_kwargs)
    if query:
        _do_query(query, func_kwargs)
    if form:
        _do_form(form, func_kwargs)
    if body:
        _do_body(body, func_kwargs)
except ValidationError as e:
    # Create a JSON response with validation error details
    validation_error_callback = getattr(current_app, "validation_error_callback", None)
    if validation_error_callback:
        response = validation_error_callback(e)
    else:
        response = make_response(e.json())
        response.headers["Content-Type"] = "application/json"
        response.status_code = getattr(current_app, "validation_error_status", 422)
    return response