I have a login page. Upon submission if 'webmail' is selected, the request
should be redirected to the webmail server, with the credentials submitted but
under different keys. Here's what I'm trying now:
if form.validate_on_submit():
if form.destination.data == 'webmail':
form.rc_user.data = form.email.data
form.rc_password.data = form.password.data
return redirect('https://example.com/webmail/', code=307)
This almost works: the POST is redirected to webmail. However the values
submitted are the default values, not the assigned values.
I have some more issues though:
the keys should be _user and _pass, but Flask seems to blow up with
leading-underscore field names.
I do not want to add these fields to the original class. I want to subclass
upon submission, somewhat as follows:
if form.validate_on_submit():
if form.destination.data == 'webmail':
class WebmailLoginForm(LoginForm):
rc_user = EmailField('user', default=form.email.data)
form = WebmailLoginForm(request.form)
return redirect('https://example.com/webmail/', code=307)
When I do this, the added fields show up as UnboundField and are not
submitted.
When issuing a redirect, the browser is simply told to resubmit to another server. I.e. it's too late for the server to influence the request.
So either: start a new request, or use javascript to change the submit target.
Thanks to my colleague Johan for kickstarting my brain.
Related
I'm trying to understand how django populates the data in a form when I go back in a browser
In the debugger when I go back in the browser it generates a GET request, not a POST and so the form is not bound and has no self.data.
How do I get the existing values of the fields in a django form when going back in the browser?
(note I am using session with database backend)
While creating the form use initial data.
data = { 'field_1': 'value'}
my_form = MyForm(initial=data)
The error is in the question. The data is coming from the browser cache not the backend.
I'm aware that there is a context variable called "next" which allows you to specify the URL to redirect to after a page, which is commonly used when you want to redirect a user to a login page, then redirect them back to the page they were at before the login page once they've logged in.
In my views I've resorted to manually setting it via the URL such as redirecting to /login/?next=/someurl, but this isn't a clean way. I've tried googling and such, but there is surprisingly little information about it online.
How exactly do you set the context variable "next"? My site has a form that anyone can see, but only logged in users can submit. Right now if the user isn't logged in, they will get redirected to the login page with the "?next=/someurl/" attached to it so they get sent back to the original form once they log in.
However, from the login page there is a link to the sign up page for users who don't have an account, and I want to set "next" to be the original form page so that after they sign up they are redirected back to the original form. Any ideas or advice?
It sounds like you want to not simply use next for one redirect, but persist it across two redirects:
Some form page -> login -> signup -> Get back to some form
For the login page by itself, Django provides some automatic help for this (if you use the built-in auth views). But the second hop to the signup page requires some custom code explained below.
If you are using Django's built-in login view, and have created your own template for it, then Django will pass the current value of next to the template as a context variable called (appropriately) next. You can use that in the link to your sign-up page like this:
Sign me up!
Consequently, in the view you create to handle your user signup page, the value of next will be accessible as a GET param:
def signup(request):
if request.method == 'GET':
next = request.GET.get('next', None)
if next:
# Add it as a hidden input in your signup form
# Or re-append it as a GET param
# Or stick it in the user's session, which is
# what this example does:
request.session['next'] = next
Finally, in the same signup view, when you respond to the POSTed signup form, retrieve the next value in whichever way you chose to propogate it in the GET request, and redirect to it's value.
def signup(request):
....
# POST handling section
if signup_form.is_valid():
next = request.session.get('next', None)
if next:
# See caution note below!
return redirect(next)
Caution:
Be aware that you should check and sanitize the next value before you redirect to it after processing the signup form, to prevent browser-side tampering. For example, it's common to validate that the URL belongs to your own domain (if that's appropriate) and/or that Django's resolve function is able to successfully resolve it.
So I have a a HTML page with a table in it which contains details of a certain model. Each row contains details of a different object. I have a cell for a button as well.
Now, what I want is for the user to be able to click on the button and it should take them to the appropriate page for that particular user that they've clicked on. The way I can do this now is by creating a URL that takes a user_id argument along with a view to redirect it to a template. This url can then be added to the button. However, I don't want the user_id to be shown in the URL (being shown in Inspect Element is okay (as in the row ID)).
This rushed, so sorry. How can I do this?
Is there a way to do it without putting any information whatsoever in the URL?
Thank you!
One way to do this is to send user ids from a POST instead of a GET for getting the user info, when the user clicks the button, you submit a hidden form which contains user_id (which you will update accordingly) and pass it to Django. On this POST call you will wire a render of the page for the user according to the POST parameter you are expecting containing the user id.
You can read the post parameters on a request via:
request.POST.get('user_id')
The downside of this approach is that you won't be able to share the link for a certain user, because the link will only contain the get parameters.
Maybe you can refactor your application to use some kind of SPA framework on the front-end. In this way you can load any content on your current page and the URL never changes if you don't want. Take a look for example at AngularJS or Durandal. Both works well with Django.
You can also solve the problem by using POST instead of GET but in my opinion that's not a very elegant solution because POST requests should be used just when you send data to the server.
If your worried about security I don't think keeping the user_id secret will be effective but if for some other reason you have to do this put it in session and redirect to user page without any parameters.
Put your table inside a form and store the id in an attribute of the button on each row:
<button class="mybutton" data-id="{{ my_object.id }}">view</button>
Put a hidden field at the bottom of your form:
<input type="hidden" id="user_id" name="user_id" />
Javascript:
$("table .mybutton").click(function(e) {
e.preventDefault();
$("#user_id").val($(this).attr("data-id"));
$("#my_form").submit();
});
In your table view:
if request.method == "POST":
request.session["user_id"] = request.POST.get('user_id')
return redirect("user_page")
In your details view:
user_id = request.session["user_id"]
creating urls
If the url is relevant to the user; then use the user_id; e.g. http://example.com/mysite/users/<user_id>/userstuff.
obfuscation is not security.
obfuscation is not a permission scheme.
Other possibilities:
http://example.com/mysite/users/<uniqueusername>/userstuff.
http://example.com/mysite/users/<slug>/userstuff.
http://example.com/mysite/users/<encoded>/userstuff, where encoded is either 2-way encoding, or a field on the user model that is unique.
getting logged in user (request.user)
If the url has nothing to do with the user, but you need to get the authenticated user then read the docs: https://docs.djangoproject.com/en/1.7/topics/auth/default/#authentication-in-web-requests.
def my_view(request):
if request.user.is_authenticated():
# use request.user
else:
# something else
For my website pretty much every page has a header bar displaying "Welcome, ABC" where "ABC" is the username. That means request.user will be called for every single request resulting in database hits over and over again.
But once a user is logged in, I should be able to store his user instance in his cookie and encrypt it. That way I can avoid hitting the database repeatedly and just retrieve request.user from the cookie instead.
How would you modify Django to do this? Is there any Django plugins that does what I need?
Thanks
You want to use the session middleware, and you'll want to read the documentation. The session middleware supports multiple session engines. Ideally you'd use memcached or redis, but you could write your own session engine to store all the data in the user's cookie. Once you enable the middleware, it's available as part of the request object. You interact with request.session, which acts like a dict, making it easy to use. Here are a couple of examples from the docs:
This simplistic view sets a has_commented variable to True after a user posts a comment. It doesn’t let a user post a comment more than once:
def post_comment(request, new_comment):
if request.session.get('has_commented', False):
return HttpResponse("You've already commented.")
c = comments.Comment(comment=new_comment)
c.save()
request.session['has_commented'] = True
return HttpResponse('Thanks for your comment!')
This simplistic view logs in a "member" of the site:
def login(request):
m = Member.objects.get(username=request.POST['username'])
if m.password == request.POST['password']:
request.session['member_id'] = m.id
return HttpResponse("You're logged in.")
else:
return HttpResponse("Your username and password didn't match.")
This smells of over-optimisation. Getting a user from the db is a single hit per request, or possibly two if you use a Profile model as well. If your site is such that an extra two queries makes a big difference to performance, you may have bigger problems.
The user is attached to the request object using the Authentication Middleware provided by django (django.contrib.auth.middleware). It users a function the get_user function in django.contrib.auth.init to get the user from the backend you are using. You can easily change this function to look for the user in another location (e.g. cookie).
When a user is logged in, django puts the userid in the session (request.session[SESSION_KEY]=user.id). When a user logs off, it erases the user's id from the session. You can override these login and logoff functions to also store a user object in the browsers cookie / erase user object from cookie in the browser. Both of these functions are also in django.contrib.auth.init
See here for settting cookies: Django Cookies, how can I set them?
Once you have proper caching the number of database hits should be reduced significantly - then again I'm not really and expert on caching. I think it would be a bad idea to modify request.user to solve your problem. I think a better solution would be to create some utility, method or custom template tag that attempts to load your require user data from the cookie, and return the result. If the user data is not found in the cookie, then a call to request.user should be made, save the data to the cookie, and then return the result. You could possibly use a post_save signal to check for changes to the user data, so that you can make update to the cookie as required.
This is something I've wondered about in a couple of frameworks that I've messed around with. Assuming I don't want to automatically log a user in when they register (I want them to activate) how can I make it so a user can't just visit the "register-success" page? Right now, here's what I have:
def register(request):
if request.method == 'POST':
rf = forms.RegisterForm(request.POST)#register form
pf = forms.ProfileForm(request.POST)#profile form (additional info)
lf = forms.LoginForm()#login form is also on this page but is empty when registering
if rf.is_valid() and pf.is_valid():
newuser = User(username=rf.cleaned_data['username'],email=rf.cleaned_data['email'])
newuser.set_password(rf.cleaned_data['password'])
newuser.save()
#need to mark newuser as inactive still
profile = pf.save(commit=False)
profile.user = newuser
profile.save()
return HttpResponseRedirect("/register-success/")
return render_to_response("authentication/index.html", {'rform': rf, 'pform':pf,'lform':lf})
return main(request)
def register_success(request):
return render_to_response("authentication/register-success.html")
My url-conf:
(r'^register-success/$','register_success'),
The other way I thought to do it was to just render_to_response("authentication/register-success.html") and not do the redirect. The benefit is, no one can access the register-success.html page, the downside is if the user refreshes the page it will try and resubmit the POST. What's the best practice?
I would stick with the redirect, getting duplicate users is a fairly large risk. What is the risk of someone seeing your register success page who hasn't registered? If there is a risk, you could always generate a random token, put it in session and pass it to your register-success page and then in your view check that the token matches. But that seems like a lot of work for what typical success pages are.
My recommendation would be to not worry about people being able to get to that page without registering. If it is just static HTML, there can't be any risk with showing to to everybody, right?
You can set the cookie, a session key in register view that you can check for in the register_success view only on its presence render the page, else redirect to main register.