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how to setup custom middleware in django

Posted by: admin November 30, 2017 Leave a comment

Questions:

I am trying to create middleware to optionally pass a kwarg to every view that meets a condition.

The problem is that I cannot find an example of how to setup the middleware. I have seen classes that override the method I want to, process_view:

Class CheckConditionMiddleware(object):  
    def process_view(self, request):  

        return None  

But where do I put this class? Do I create a middleware app and put this class inside of it and then reference it in the settings.middleware ?

Answers:

First: The path structure

If you don’t have it you need to create the middleware folder within your app following the structure:

yourproject/yourapp/middleware

The folder middleware should be placed in the same folder as settings.py, urls, templates…

Important: Don’t forget to create the __init__.py empty file inside the middleware folder so your app recognize this folder

Second: Create the middleware

Now we should create a file for our custom middleware, in this example let’s supose we want a middleware that filter the users based on their IP, we create a file called filter_ip_middleware.py inside the middleware folder with this code:

class FilterIPMiddleware(object):
    # Check if client IP is allowed
    def process_request(self, request):
        allowed_ips = ['192.168.1.1', '123.123.123.123', etc...] # Authorized ip's
        ip = request.META.get('REMOTE_ADDR') # Get client IP
        if ip not in allowed_ips:
            raise Http403 # If user is not allowed raise Error

       # If IP is allowed we don't do anything
       return None

Third: Add the middleware in our ‘settings.py’

We need to look for:

  • MIDDLEWARE_CLASSES (django < 1.10)
  • MIDDLEWARE (django >= 1.10)

Inside the settings.py and there we need to add our middleware (Add it in the last position). It should be like:

MIDDLEWARE = ( #  Before Django 1.10 the setting name was 'MIDDLEWARE_CLASSES'
    'django.middleware.common.CommonMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
     # Above are django standard middlewares

     # Now we add here our custom middleware
     'yourapp.middleware.filter_ip_middleware.FilterIPMiddleware'
)

Done ! Now every request from every client will call your custom middleware and process your custom code !

Questions:
Answers:

It will be helpful in the case of When you know what type of Exception occurs in the views.
From the above I have Created my own Custom class like

from .models import userDetails

class customMiddleware(object):

    def process_request(self,request):
        result=''
        users = userDetails.objects.all()
        print '-->',users ,'---From middleware calling ---'

        username=request.POST.get("username")
        salary = request.POST.get("salary")
        if salary:
            try:
                result = username+int(salary)
            except:
                print "Can't add"

It will be executed when the exception occur in the case of string and integer addition.

You can write Corresponding views for above middleware class