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.
Related
According to the Django documentation, the HttpRequest object has a "user" attribute that represents the currently logged in user if the Django installation has activated AuthenticationMiddleware. How does the request object know what the user is? Does the middleware set the user in a cookie and save that cookie to the client browser after the user logs in? In my code, I save the user's ID (from the auth_user table) to a session variable after they've logged in and I usually examine it on each page. If this information is always available in the request object, I shouldn't need to do this. All I should need to do is examine request.user.id. Is this correct?
Thanks.
Yes you've got it, except the user data is stored in the session. You're doing redundant work by keeping track off all that yourself - this something Django is great at!
Check out this documentation on user objects
.. and this article on all of it specifically.
User id is stored not in the cookie but in the session.
And yes, you shouldn't save this data in the session by yourself:
if request.user.is_authenticated():
user_id = request.user.id
If the view should be available for logged users only then instead of checking of request.user.is_authenticated() use the #login_required decorator.
I have a webapp that allows authenticated as well as anonymous users to start entering some form data. If a user is happy with his/her input, he/she can save that form to the server. This is a very similar problem to a shopping cart application that does not require login until checkout time.
For the authenticated user, implementing a save button is trivial. However for the anonymous user, the form data need to be stored somewhere while authentication is taking place, then correctly retrieved after logged in. Can someone please suggest some general strategies to go about this?
I found this link that is promising but I want to be thorough about this topic.
I think the correct way of doing this is to use django sessions. Basically each user (anonymousUser included) has a session during its stay on the website (or even more).
If you have a form that you want to store for a specific session, you can do it by using
request.session['myform'] = form
you get it by
request.session['myform']
and you can delete it using
del request.session['myform']
Basically Django pickles a dictionary of the session and saves it in a place (typically the database, but can be on other place as explained in django sessions).
To learn Django, I was making a very basic app which does the following:
Takes a user's login (checks id password in a database).
If user exists and password is right, give user option to either insert,delete or update.
If insert, user can insert an entry into a common table.
Similarly for delete or update.
I was cruising through this but I just got stuck.
My Login page is /index/.
Option for insert/delete/update is at /application/.
Now next, page is displayed according to insert/delete/update at /application/action/
Now the problem is that after completing one insertion, I want to return to /application to carry on my next operation.
But if I do that, I get this error
"Key 'userid' not found in <QueryDict: {}>"
So the view for /application/ is expecting the userid and password in request.POST.
How do I get around this without using external user login modules. I just want a very basic login system just to learn.
Django comes with user authentication built in. I don't think it is external as it is included in django.contrib.
If you use the built in user authentiaction and User model, you will not have to pass the userid to each view. Django will automatically retrieve the logged in user from the session and make it available as a property of the request object.
So using built in user and authentiaction, after logging in a user, you can access that user at
request.user
I need some advice / ideas if someone is inclined to help: I have a javascript interface for manipulating pictures. Basically it's about moving photos around. Once it's done the position of images is saved into a Django form and then saved to database with the owner saved as the current user. Now the trick is that I would like to be able to allow non registered users to play with this interface and then if they like the result they hit save and are redirected to an account registration page and only then the form is actually saved with their user as the owner.
What comes to my mind now is to keep the values of the form in session but I don't know what will happen to the session once the anonymous user registers and becomes another user. I was also thinking of using a 'next' parameter in the registration process with the url filled with get parameters that would be the content of the form but then I don't know if userena is ready to allow that.
Any light on this is welcome.
Well, we did similar thing on our site.
When unregistered user attach photos we save objects to database and assign unique hash which was generated when user came to the page with form. When user hit submit we pass this hash in url and on the next step, when user wants to register, we just get objects from database by this hash and assign user_id to them.
Also we have a cron job which do clean up and removes all lost objects
P.S. Sorry for my english i hope you'll get my point
Save the object without the user and store a reference of that object in the session (or (signed) cookie). If if the user registers, update all the objects with the newly created user.
Another approach would be to store the data in the browser (html5 localstorage and fallbacks, or similar) and only insert it into the database once the user has signed up. You would need to make sure both things happen inside the same browser 'instance', but things would be easier in the server side.
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.