基于视图 kwargs 编写 Django 会话中间件

Question

I am in need of the ability to not set a session in my Django App when I hit specific URLS because the URLs dictate which DB to go to and the session django uses is stored in those DBs

So, please how can I write the SessionMiddleware to use process_view instead of process_response() ?

import time
from importlib import import_module

from django.conf import settings
from django.contrib.sessions.backends.base import UpdateError
from django.contrib.sessions.exceptions import SessionInterrupted
from django.utils.cache import patch_vary_headers
from django.utils.deprecation import MiddlewareMixin
from django.utils.functional import SimpleLazyObject
from django.utils.http import http_date


class SessionMiddleware(MiddlewareMixin):
    pass
    # RemovedInDjango40Warning: when the deprecation ends, replace with:
    #   def __init__(self, get_response):
    def __init__(self, get_response=None):
        super().__init__(get_response)
        engine = import_module(settings.SESSION_ENGINE)
        self.SessionStore = engine.SessionStore

    def process_request(self, request):
        session_key = request.COOKIES.get(settings.SESSION_COOKIE_NAME)
        print(request.__dict__)
        if hasattr(request, 'client_url'):
            print('client url')
            request.session = self.SessionStore(session_key)
            print(self.SessionStore(session_key), self.SessionStore(session_key).__dict__)
        else:
            from django.contrib.sessions.backends.db import SessionStore
            s = SessionStore(session_key)
            print('session eluded...')
            request.session = s
            print('session eluded after...')
            request.session = {}


    def process_view(self, request, callback, callback_args, callback_kwargs):
        # I NEED TO CALL THIS TO ENSURE SESSIONS ARE IN A SPECIFIC DB
        pass

    def process_response(self, request, response):
        """
        If request.session was modified, or if the configuration is to save the
        session every time, save the changes and set a session cookie or delete
        the session cookie if the session has been emptied.
        """
        try:
            accessed = request.session.accessed
            modified = request.session.modified
            empty = request.session.is_empty()
        except AttributeError:
            return response
        # First check if we need to delete this cookie.
        # The session should be deleted only if the session is entirely empty.
        if settings.SESSION_COOKIE_NAME in request.COOKIES and empty:
            response.delete_cookie(
                settings.SESSION_COOKIE_NAME,
                path=settings.SESSION_COOKIE_PATH,
                domain=settings.SESSION_COOKIE_DOMAIN,
                samesite=settings.SESSION_COOKIE_SAMESITE,
            )
            patch_vary_headers(response, ('Cookie',))
        else:
            if accessed:
                patch_vary_headers(response, ('Cookie',))
            if (modified or settings.SESSION_SAVE_EVERY_REQUEST) and not empty:
                if request.session.get_expire_at_browser_close():
                    max_age = None
                    expires = None
                else:
                    max_age = request.session.get_expiry_age()
                    expires_time = time.time() + max_age
                    expires = http_date(expires_time)
                # Save the session data and refresh the client cookie.
                # Skip session save for 500 responses, refs #3881.
                if response.status_code != 500:
                    try:
                        request.session.save()
                    except UpdateError:
                        raise SessionInterrupted(
                            "The request's session was deleted before the "
                            "request completed. The user may have logged "
                            "out in a concurrent request, for example."
                        )
                    response.set_cookie(
                        settings.SESSION_COOKIE_NAME,
                        request.session.session_key, max_age=max_age,
                        expires=expires, domain=settings.SESSION_COOKIE_DOMAIN,
                        path=settings.SESSION_COOKIE_PATH,
                        secure=settings.SESSION_COOKIE_SECURE or None,
                        httponly=settings.SESSION_COOKIE_HTTPONLY or None,
                        samesite=settings.SESSION_COOKIE_SAMESITE,
                    )
        return response

from django.contrib import auth

def get_user(request):
    if not hasattr(request, '_cached_user'):
        request._cached_user = auth.get_user(request)
    return request._cached_user



class AuthenticationMiddleware(MiddlewareMixin):
    def process_request(self, request):
        assert hasattr(request, 'session'), (
            "The Django authentication middleware requires session middleware "
            "to be installed. Edit your MIDDLEWARE setting to insert "
            "'django.contrib.sessions.middleware.SessionMiddleware' before "
            "'django.contrib.auth.middleware.AuthenticationMiddleware'."
        )
        request.user = SimpleLazyObject(lambda: get_user(request))

Everything I have tried does not work. I need the session to not save unless there is a URL kwarg, client URL. How do I do this?

Answer 1

The solution was to alter process_request() in order to check if client_url is located in the resolved request.path_info variable like so:

import time
from importlib import import_module

from django.conf import settings
from django.contrib.sessions.backends.base import UpdateError
from django.contrib.sessions.exceptions import SessionInterrupted
from django.urls import resolve
from django.utils.cache import patch_vary_headers
from django.utils.deprecation import MiddlewareMixin
from django.utils.functional import SimpleLazyObject
from django.utils.http import http_date


class SessionMiddleware(MiddlewareMixin):
    pass
    # RemovedInDjango40Warning: when the deprecation ends, replace with:
    #   def __init__(self, get_response):
    def __init__(self, get_response=None):
        super().__init__(get_response)
        engine = import_module(settings.SESSION_ENGINE)
        self.SessionStore = engine.SessionStore

    def process_request(self, request):    # HERE!!!!!
        session_key = request.COOKIES.get(settings.SESSION_COOKIE_NAME)
        # print(request.path, resolve(request.path_info).kwargs)

        if 'client_url' in resolve(request.path_info).kwargs:
            print('client url found')
            request.session = self.SessionStore(session_key)
            # print(self.SessionStore(session_key), self.SessionStore(session_key).__dict__)
        else:
            # this is an error because the db cannot be found without client_url,
            # but we need to assign session or auth does not work
            print('session eluded...')
            request.session = {}


    def process_view(self, request, callback, callback_args, callback_kwargs):
        # I NEED TO CALL THIS TO ENSURE SESSIONS ARE IN A SPECIFIC DB
        pass

    def process_response(self, request, response):
        """
        If request.session was modified, or if the configuration is to save the
        session every time, save the changes and set a session cookie or delete
        the session cookie if the session has been emptied.
        """
        try:
            accessed = request.session.accessed
            modified = request.session.modified
            empty = request.session.is_empty()
        except AttributeError:
            return response
        # First check if we need to delete this cookie.
        # The session should be deleted only if the session is entirely empty.
        if settings.SESSION_COOKIE_NAME in request.COOKIES and empty:
            response.delete_cookie(
                settings.SESSION_COOKIE_NAME,
                path=settings.SESSION_COOKIE_PATH,
                domain=settings.SESSION_COOKIE_DOMAIN,
                samesite=settings.SESSION_COOKIE_SAMESITE,
            )
            patch_vary_headers(response, ('Cookie',))
        else:
            if accessed:
                patch_vary_headers(response, ('Cookie',))
            if (modified or settings.SESSION_SAVE_EVERY_REQUEST) and not empty:
                if request.session.get_expire_at_browser_close():
                    max_age = None
                    expires = None
                else:
                    max_age = request.session.get_expiry_age()
                    expires_time = time.time() + max_age
                    expires = http_date(expires_time)
                # Save the session data and refresh the client cookie.
                # Skip session save for 500 responses, refs #3881.
                if response.status_code != 500:
                    try:
                        request.session.save()
                    except UpdateError:
                        raise SessionInterrupted(
                            "The request's session was deleted before the "
                            "request completed. The user may have logged "
                            "out in a concurrent request, for example."
                        )
                    response.set_cookie(
                        settings.SESSION_COOKIE_NAME,
                        request.session.session_key, max_age=max_age,
                        expires=expires, domain=settings.SESSION_COOKIE_DOMAIN,
                        path=settings.SESSION_COOKIE_PATH,
                        secure=settings.SESSION_COOKIE_SECURE or None,
                        httponly=settings.SESSION_COOKIE_HTTPONLY or None,
                        samesite=settings.SESSION_COOKIE_SAMESITE,
                    )
        return response