I'm running a site on Django that has been in operation for a few years. We use sessions with a Redis cache backend. After a reasonably minor update of Django to 1.11.16 from an earlier 1.11.* version, we're seeing that user sessions are being ended for no obvious reason.
One dependable way to get a session to end is to navigate to a url that causes a history.replaceState() to replace the URL. As soon as that happens - the old sessions ends, the user is logged out, and a new session is started.
Any clues would help.
I am currently developing guest checkout in django as I don't want to use django-oscar which gives guest checkout functionality. I searched and got to the conclusion that it can be done through session and got to know that when user logs in the system at that time row will be created in django_session table. So I will have to create manual entry in django_session for my guest checkout. Can anyone please throw some light on how and which will be the best way to do it?
The easiest way it would be to set request.session['user'] to some default value (e.g. guest) by default (you can do
try:
request.session['user']
except KeyError:
request.session['user'] = 'guest'
at the start of every view function (pr functions that can be accessible directly by typing some URL. That's what I've always done and it makes miracles ;). What it actually does is checks whether a user is logged in (request.session has the key user) or not (request.session does not have the key user). When user logs in, set request.session['user'] to his username.
You don't want to touch the django_session table yourself.
Instead, please read
a tutorial about the session framework, or
the more in-depth documentation
The gist of it is that you can store things in the session dict using
request.session['foo'] = True
and they will be transparently persisted using a cookie. You can retrieve them similarly.
This may sound too easy to understand but I am not sure I am having my head around it.
When a user is signing up in the first page of my app, I have request.session['user_id'] set which is used in page two of the sign up to complete registration. The user_id is the primary key to user in USER TABLE but I don't want to store user_id in session. I fear it might be tampered with and the WRONG row might get updated.
I would want something like a token that would be generated by my script but Django's SESSION TABLE only has three columns (session_key, session_data, expire_date) and it saves session details to it automatically.
My questions precisely are:
Can I tinker with the SESSION TABLE and add a session_token to it or I have to create my own table?
How do I get the session_token to automatically save like other columns in Django SESSION TABLE?
Or is `request.session['user_id'] okay and safe?
Do all these also apply to COOKIES and why do I need to use cookies when SESSION_EXPIRE_AT_BROWSER_CLOSE is set to FALSE?
The session is stored in the database, not in the user's cookie. There is no way for the user to change that data. The only thing stored in the cookie is the hash of the session ID itself.
I have an application where I would like to display the number of users that are logged into the system. Im trying to determine the cleanest way to do this that will not create a large load on the system.
I know that the system keeps track of the "last logged in time" So I could do a query and aggreate the number of users whose last login is within a given time?
Are there better solutions??
Any thoughts are welcome!! Please.
Using the last logged in time doesn't work. Your sessions can last for days/weeks so you won't know the amount of active users that way.
One solution would be to create a table with login sessions where you store that session id in a session cookie. Session cookies expire once the user has closed his/her browser window so it should give you quite an accurate estimation of when people logged in. If you actually want to store the entire session duration, than you will also have to update the table with every page view to store the time that the user was last active. This would be slightly heavier for your database ofcourse.
Background
I have a custom authentication back end for our django applications that refers to an LDAP server.
As soon as I authenticate someone, I have a wealth of information that our network infrastructure guys put in the LDAP server about the user - their last names (which can change, for instance, if they marry), their e-mails (which can also change), plus other company specific information that would be useful to transfer to the Django auth_user table or profile table for local reference. (*)
To take advantage of this data, as of now, in our custom authenticate method I'm looking up (if it is an existing user logging in) or creating a new (if a new user that never logged in to our Django apps) user, making any changes to it and saving it.
This smells bad to me. Authentication should be about saying yay or nay in granting access, not about collecting information about the user to store. I believe that should happen elsewhere!
But I don't know where that elsewhere is...
My current implementation also causes a problem on the very first login of a user to one of our Django apps, because:
New user to our apps logs in - request.user now has a user with no user.id
My custom authenticate method saves the user information. Now the user exists in the DB
django.contrib.auth.login() kicks in and retrieves the request.user (which still has no user.id and no idea that authenticate saved the user) and tries to save an update to last logged in date.
Save fails because there is already a row in the database for that username (unique constraint violation)
Yes, this only happens the very first time a user logs in; the next time around it will be an update, request.user will have a user.id and everything is fine.
Edit: I'm investigating the striked-out area above. The login code clearly only uses the request.user if the user is None (which, coming out of the validation of the AuthenticationForm it shouldn't be. I probably am doing something wrong in my code...
But it still smells bad to have the authentication doing more than just, you know, authenticating...
Question
What is the right place to plug in changes to the user instance during the login process?
Ideally I would be able to, in my custom authenticate method, state that after login the information collected from a LDAP server should be written to the user instance and potentially the user profile instance.
(*) I do this local caching of the ldap information because I don't want to depend on it being up and running to let users log in to my systems; if ldap is down, the last username and password in auth_user are accepted.
I've done similar things by writing my own authentication backend and putting it in the authenticate() method. The code is public and up here. I also included a pluggable system of "mappers" to do most of the work that isn't just authenticating the user (eg, getting fullname from ldap, automatically creating groups based on "affiliations" that our auth service gives us, and mapping certain users and affiliations into staff/superuser roles automatically).
Basically, the authenticate method looks like:
def authenticate(self, ticket=None):
if ticket is None:
return None
# "wind" is our local auth service
(response,username,groups) = validate_wind_ticket(ticket)
if response is True:
try:
user = User.objects.get(username=username)
except User.DoesNotExist:
user = User(username=username, password='wind user')
user.set_unusable_password()
# give plugins a chance to pull up more info on the user
for handler in self.get_profile_handlers():
handler.process(user)
user.save()
# give plugins a chance to map affiliations to groups
for handler in self.get_mappers():
handler.map(user,groups)
return user
else:
# i don't know how to actually get this error message
# to bubble back up to the user. must dig into
# django auth deeper.
pass
return None
So I pretty much agree with you that authentication should be just a yes/no affair and other stuff should happen elsewhere, but I think with the way Django sets things up, the path of least resistance is to put it in with authentication. I do recommend making your own authentication code delegate that stuff to plugins though since that's within your control.
I'm only fetching the LDAP data on their very first login though (when the auth_user row gets added). Anytime they login after that, it just uses what it already has locally. That means that if their LDAP info changes, it won't automatically propagate down to my apps. That's a tradeoff I'm willing to make for simplicity.
I'm not sure why you're running into problems with the first login though; I'm taking a very similar approach and haven't run into that. Maybe because the login process on my apps always involves redirecting them to another page immediately after authentication, so the dummy request.user never gets touched?
This will be a two part answer to my own question.
What is the right place to plug in changes to the user instance during the login process?
Judging from the Django code, my current implementation, and thraxil's answer above, I can only assume that it is expected and OK to modify the user instance in a custom authenticate() method.
It smells wrong to me, as I said in my question, but the django code clearly assumes that it is possible that a user instance will be modified and I can find no other hooks to apply changes to the user model AFTER authentication, elsewhere.
So, if you need an example, look at thraxil's code - in the selected answer to my question.
Why my implementation is working differently from thraxil's and generating a unique constraint violation?
This one was rather nasty to figure out.
There is absolutely nothing wrong with Django. Well, if it already supported multiple databases (it is coming, I know!!!) I probably wouldn't have the problem.
I have multiple databases, and different applications connect to one or more different ones. I'm using SQL Server 2005 (with django_pyodbc). I wanted to share the auth_user table between all my applications.
With that in mind, what I did was create the auth models in one of the databases, and then create SQL Server synonyms for the tables in the other databases.
It works just fine: allowing me to, when using database B, select/insert/update/delete from B.dbo.auth_user as if it were a real table; although what is really happening is that I'm operating on A.dbo.auth_user.
But it does break down in one case: to find the generated identity, django_pyodbc does a:
SELECT CAST(IDENT_CURRENT(%s) as bigint) % [table_name]
and that doesn't appear to work against synonyms. It always returns nulls. So when in my authenticate() method I did user.save(), the saving part worked fine, but the retrieval of the identity column didn't - it would keep the user instance with a id of None, which would indicate to the django code that it should be inserted, not updated.
The workaround: I had two choices:
a) Use views instead of synonyms (this is what I did)
b) Reload the user right after a user.save() using User.objects.get(username=username)
Hope that might help someone else.