Process request in middlware before handler function

Questions and Help
#1

Hello, everybody!

I am trying to add CORS header to request in middleware, but then I get OPTIONS request
it gets into the handler function, but I won’t it. How can i prevent gets into my handler function request OPTIONS?

Or how can I process a request before a handler?

This example

@app.middleware('response')
async def CORS_middlware(request, response_query):

    CORS_HEADERS = {
        'Access-Control-Allow-Origin': 'http://127.0.0.1:8081',
        'Access-Control-Allow-Credentials': 'true',
        'Access-Control-Allow-Methods': 'GET,POST,PUT,DELETE,OPTIONS',
        'Access-Control-Allow-Headers': 'Content-Type'
    }

    if request.method == 'OPTIONS':
        resp = response.empty()
        resp.headers.update(**CORS_HEADERS)
        return resp

    response_query.headers.update(**CORS_HEADERS)
#2

Try middleware('request') instead.

#3

Thanks, it works! :grinning:

I thought that I can get response and request in one middleware, now I resolve it that:

CORS_HEADERS = {
    'Access-Control-Allow-Origin': 'http://127.0.0.1:8081',
    'Access-Control-Allow-Credentials': 'true',
    'Access-Control-Allow-Methods': 'GET,POST,PUT,DELETE,OPTIONS',
    'Access-Control-Allow-Headers': 'Content-Type'
}

@app.middleware('request')
async def OPTIONS_CORS(request):

    if request.method == 'OPTIONS':
        resp = response.empty()
        resp.headers.update(**CORS_HEADERS)
        return resp


@app.middleware('response')
async def CORS(request, response_query):
    response_query.headers.update(**CORS_HEADERS)

Docs from https://sanic.readthedocs.io/en/latest/sanic/middleware.html#responding-early
confuses me in this example

@app.middleware('request')
async def halt_request(request):
    return text('I halted the request')

@app.middleware('response')
async def halt_response(request, response):
    return text('I halted the response')

It is not obvious that the second example is executed after the handler function.