Hooks

SpecTree provides before and after hooks so you can customize what happens around validation — for example, recording metrics, logging validation errors, or building a custom error response.

Signatures

Note

The model_adapter argument was added in SpecTree v3. Hooks written for v2 accepted only four arguments. See the migration guide for details.

Both hooks receive five positional arguments:

def before(req, resp, req_validation_error, instance, model_adapter):
    ...


def after(req, resp, resp_validation_error, instance, model_adapter):
    ...

• req: the request object provided by the web framework

• resp: for before, the response SpecTree will return if request validation failed; for after, the response from the endpoint function

• req_validation_error / resp_validation_error: the validation error, or None if validation passed

• instance: the class instance when the endpoint is a class method, otherwise None

• model_adapter: the model adapter used by the current SpecTree instance, giving access to adapter-specific error details and serialization

When the hooks run

• before runs after request validation and before the endpoint function. If request validation failed, the endpoint is skipped and the resp argument is the error response SpecTree generated.

• after runs after the endpoint function and response validation.

Setting hooks

Hooks can be set globally on the SpecTree instance:

from spectree import SpecTree


def custom_before(req, resp, req_validation_error, instance, model_adapter):
    if req_validation_error:
        resp.status = 400
        resp.media = {"errors": model_adapter.validation_errors(req_validation_error)}


spec = SpecTree("falcon", before=custom_before)

or per endpoint through validate:

@spec.validate(query=Query, before=custom_before)
def handler():
    ...

If you don’t provide hooks, SpecTree uses spectree.utils.default_before_handler() and spectree.utils.default_after_handler(), which log validation errors.