django - why is this custom middleware not working - django

Question

I am building a website using django 1.10. I have written a middleware class to restrict the number of page views for users that are not logged in. I implemented this functionality into a separate application 'pagerestrict'
settings.py [Relevant Entries]
# Application definition
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django.contrib.sites',
'pagerestrict.apps.PagerestrictConfig',
# ...
]
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
'pagerestrict.middleware.CheckPageAccessMiddleware',
]
Middleware code (middleware.py):
from django.http import HttpResponseRedirect
from decouple import config
class CheckPageAccessMiddleware(object):
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
return self.get_response(request)
def process_request(self, request):
if not request.user.is_authenticated():
current_page_url = request.path_info.lstrip('/')
ignore_list = config('PAGE_RESTRICT_PAGE_IGNORES', cast=lambda v: [s.strip() for s in v.split(',')])
#if not current_page_url or not any(current_page_url != url for url in ignore_list):
if not current_page_url in ignore_list:
# first things first ...
if not has_attr(request, 'pages_visited'):
request.pages_visited = set()
if not has_attr(request, 'page_count'):
request.page_count = 0
if current_page_url not in request.pages_visited:
request.pages_visited.add(current_page_url)
request.page_count += 1
if request.page_count > config('PAGE_RESTRICT_PAGE_LIMIT'):
return HttpResponseRedirect(config('PAGE_RESTRICT_REDIRECT_URL'))
I tested this by going to my homepage and refreshing the browser several times - the code never seemed to be triggered. What am I missing?

Answer 1

New-style middleware does not call process_request and process_response by default. This functionally has been replaced with __call__ and the get_response function that is passed to __init__.
You need to call process_request() inside __call__ and process the return value if it is not None. The easiest way to do this is to use the MiddlewareMixin provided by Django. This will define the necessary __init__ and __call__ methods, and __call__ will call process_request() and process_response() if they are defined.
from django.utils.deprecation import MiddlewareMixin
class CheckPageAccessMiddleware(MiddlewareMixin):
def process_request(self, request):
if not request.user.is_authenticated():
current_page_url = request.path_info.lstrip('/')
ignore_list = config('PAGE_RESTRICT_PAGE_IGNORES', cast=lambda v: [s.strip() for s in v.split(',')])
#if not current_page_url or not any(current_page_url != url for url in ignore_list):
if not current_page_url in ignore_list:
# first things first ...
if not has_attr(request, 'pages_visited'):
request.pages_visited = set()
if not has_attr(request, 'page_count'):
request.page_count = 0
if current_page_url not in request.pages_visited:
request.pages_visited.add(current_page_url)
request.page_count += 1
if request.page_count > config('PAGE_RESTRICT_PAGE_LIMIT'):
return HttpResponseRedirect(config('PAGE_RESTRICT_REDIRECT_URL'))

Answer 2

I finally got this to work. It was based on the Middleware topic on the now defunct Stack Overflow Documentation site. (Attribution details can be found on the contributor page. Reference topic ID: 1721.)
from django.http import HttpResponseRedirect
from decouple import config
class CheckPageAccessMiddleware(object):
def __init__(self, next_layer=None):
"""We allow next_layer to be None because old-style middlewares
won't accept any argument.
"""
self.get_response = next_layer
def process_request(self, request):
"""Let's handle old-style request processing here, as usual."""
# Do something with request
# Probably return None
# Or return an HttpResponse in some cases
if not request.user.is_authenticated():
current_page_url = request.path_info.lstrip('/')
print ('Current page url: {0}'.format(current_page_url))
root_url = '' # root url == ('')
restrict_redirect_page = config('PAGE_RESTRICT_REDIRECT_URL')[1:] # chop of leading '/'
ignore_list = [root_url, restrict_redirect_page] + \
config('PAGE_RESTRICT_PAGE_IGNORES', cast=lambda v: [s.strip() for s in v.split(',')])
print('ignore list: %s' % ",".join([x for x in ignore_list]))
#if not current_page_url or not any(current_page_url != url for url in ignore_list):
if not current_page_url in ignore_list:
# first things first ...
if 'pages_visited' not in request.session:
request.session['pages_visited'] = ''
if 'page_count' not in request.session:
request.session['page_count'] = 0
pages_visited = [x.strip() for x in request.session['pages_visited'].split(',')]
if current_page_url not in pages_visited:
pages_visited.append(current_page_url)
request.session['pages_visited'] = ",".join(x.strip() for x in pages_visited)
request.session['page_count'] += 1
print('Request page count: {0}'.format(request.session['page_count']))
if request.session['page_count'] > config('PAGE_RESTRICT_PAGE_LIMIT', cast=int):
return HttpResponseRedirect(config('PAGE_RESTRICT_REDIRECT_URL'))
return None
def process_response(self, request, response):
"""Let's handle old-style response processing here, as usual."""
# Do something with response, possibly using request.
return response
def __call__(self, request):
"""Handle new-style middleware here."""
response = self.process_request(request)
if response is None:
# If process_request returned None, we must call the next middleware or
# the view. Note that here, we are sure that self.get_response is not
# None because this method is executed only in new-style middlewares.
response = self.get_response(request)
response = self.process_response(request, response)
return response

Answer 3

You can change import like this:
try:
from django.utils.deprecation import MiddlewareMixin
except ImportError:
MiddlewareMixin = object

Answer 4

Here is an example to show how to update the middleware when migrating to
Django ver > 1.10:
Upgrading pre-Django 1.10-style middleware
If it does not work:
You should also temporarily remove all default MIDDLEWARE class,
keeping only your custom MIDDLEWARE to make sure the previous
layers(default MIDDLEWARE) did not break the flow:
MIDDLEWARE = (
# 'django.middleware.common.CommonMiddleware',
'app.middleware.MyMiddlewareClass',
)
If you remove django.middleware.common.CommonMiddleware then it works. That could be ALLOWED_HOSTS problem.
- Replace
ALLOWED_HOSTS= ['localhost:8001']
- With
ALLOWED_HOSTS= ['localhost']

Answer 5

New-style middleware does not call process_request and process_response by default.
This functionally has been replaced with call and the get_response function that
is passed to init.NYou need to call process_request() inside call and
process the return value if it is not None.
So you can write the code that you want to put into process_request() method to call() as below:
from django.http import HttpResponseRedirect
from decouple import config
class CheckPageAccessMiddleware(object):
def __init__(self, next_layer=None):
self.get_response = next_layer
def __call__(self, request):
if not request.user.is_authenticated():
current_page_url = request.path_info.lstrip('/')
ignore_list = config('PAGE_RESTRICT_PAGE_IGNORES', cast=lambda v: [s.strip() for s in v.split(',')])
#if not current_page_url or not any(current_page_url != url for url in ignore_list):
if not current_page_url in ignore_list:
# first things first ...
if not has_attr(request, 'pages_visited'):
request.pages_visited = set()
if not has_attr(request, 'page_count'):
request.page_count = 0
if current_page_url not in request.pages_visited:
request.pages_visited.add(current_page_url)
request.page_count += 1
if request.page_count > config('PAGE_RESTRICT_PAGE_LIMIT'):
return HttpResponseRedirect(config('PAGE_RESTRICT_REDIRECT_URL'))