Adding exception handler middleware

[Vye]

What is the recommended way to add exception handlers in responder?

It looks like Starlette allows this but as far as I can tell it it's not exposed in responder.

I'm looking for something like Flask's signal error handler syntax.

@app.errorhandler(InvalidRequest)
def invalid_request_handler(exc):
    resp_data = {'status': 'error', 'errors': [e for e in exc.errors]}
    return json.dumps(resp_data), exc.status_code, {}

Starlette has app.add_exception_handler(). Is this something that can be easily exposed like app.add_middleware() is?

I cannot use the builtin HTTPException that comes with Starlette because I can't customize how the data is returned.

Is Starlette's app.add_exception_handler() available somewhere in the guts of responder? I'd be happy accessing it via unconventional means for now.

[carlodri]

for my use case I would really need a functionality along the lines of falcon.API.add_error_handler. Starlette's app.add_exception_handler() seems like a very close match, if I'm not wrong.

[Vye]

Here's the part of the API class where middleware is being registered. I can't find a way to insert my own exception handling middleware without changing api.py directly.

Is this supported?

Link to code block below:

       self.add_middleware(GZipMiddleware)

        if self.hsts_enabled:
            self.add_middleware(HTTPSRedirectMiddleware)

        self.add_middleware(TrustedHostMiddleware, allowed_hosts=self.allowed_hosts)

        self.lifespan_handler = LifespanMiddleware(LifespanHandler)

        if self.cors:
            self.add_middleware(CORSMiddleware, **self.cors_params)
        self.add_middleware(ServerErrorMiddleware, debug=debug)

Starlette (where ServerErrorMiddleware comes from) supports custom exception handlers but it seems responder doesn't initialize a Starlette app? Without it I can't use their app.add_exception_handler function.

https://www.starlette.io/applications/#customizing-exception-handling

Some guidance would be welcome!

[ClericPy]

So far, there is no reliable exception_handler way to unify the management of server exception response.