Errorhandler aiohttp webserver?

Question

How can I create http error router in aiohttp web server?

   from aiohttp import web
   routes = list()
   routes.append(web.route('POST', '/reg', handler))

How can I create for example:

routes.append(web.error_handler(404, handler404)

Answer 1

Common way to create custom error pages in aiohttp is to use middleware:

from aiohttp import web


@web.middleware
async def error_middleware(request, handler):
    try:
        response = await handler(request)
        # this is needed to handle ``return web.HTTPNotFound()`` case
        if response.status == 404:
            return web.Response(text='First custom 404 message', status=404)
        return response
    except web.HTTPException as ex:
        # this is needed to handle ``raise web.HTTPNotFound()`` case
        if ex.status == 404:
            return web.Response(text='Second custom 404 message', status=404)
        raise
    # this is needed to handle non-HTTPException
    except Exception:
        return web.Response(text='Oops, something went wrong', status=500)


app = web.Application(middlewares=[error_middleware])

One more example is here