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Checking whether element is in ManyToMany field in Django

Hi so I have an attend session button that when clicked adds the user to the session. I got it working but I want to add a check to see whether the user is already in the ManyToMany field of attendees before I add them. How would I go about doing that?
Here is my view for it
def attend_session(request):
session = Study.objects.get(pk=request.POST['session_id'])
stud = Student.objects.get(student_user=request.user)
if request.method == "POST":
# Add check here to see if student is already attending
session.attendees.add(stud)
session.save()
return HttpResponseRedirect(reverse('study:sessions'))

You can check with:
from django.shortcuts import get_object_or_404, redirect
def attend_session(request):
session = get_object_or_404(Study, pk=request.POST['session_id'])
stud = get_object_or_404(Student, student_user=request.user)
if request.method == 'POST':
if stud not in session.attendees.all():
session.attendees.add(stud)
return redirect('study:sessions')
Note: It is often better to use get_object_or_404(…) [Django-doc],
then to use .get(…) [Django-doc] directly. In case the object does not exists,
for example because the user altered the URL themselves, the get_object_or_404(…) will result in returning a HTTP 404 Not Found response, whereas using
.get(…) will result in a HTTP 500 Server Error.
Note: You can make use of redirect(…) [Django-doc] instead
of first calling reverse(…) [Django] and
then wrap it in a HttpResponseRedirect object [Django-doc].
The redirect(…) function does not only offer a more convenient signature to do this, it also for example will use the
.get_absolute_url() method [Django-doc]
if you pass it a model object.

Django redirecting url with changed values

I have urls that take a parameter called board_slug. Before getting the template the view will replace the slug if its name is wrong and redirect it. I have already made the code for fixing the slug but do not know how insert the fixed board_slug into the new url. This code is run across multiple views so it has to work with all the following kinds urls:
url(r'^boards/(?P<board_slug>[^/]+)/$', views.BoardView.as_view(), name='board'),
url(r'^/front-thing/boards/(?P<board_slug>[^/]+)/new/$', views.BoardView.as_view(), name='new_board'),
url(r'^boards/(?P<board_slug>[^/]+)/etc...$', views.BoardView.as_view(), name='anything_with_board'),
class BoardView(View):
template_name = 'forums/board.html'
def get(self, request, board_slug):
if wrong:
url = get_django_url
url.board_slug = 'new-slug'
return redirect(url)
else:
return template

How can i route my URL to a common method before passing to actual view in Django

Here is my code looks like :-
url.py file :-
from rest_framework import routers
from view_user import user_signup,user_login
router = routers.DefaultRouter()
urlpatterns = [
url(r'^api/v1/user_signup',csrf_exempt(user_signup)),
url(r'^api/v1/user_login',csrf_exempt(user_login))
]
view_user.py file:-
def user_signup(request):
try:
if request.method == 'POST':
json_data = json.loads(request.body)
return JsonResponse(result, safe=False)
except Exception as e:
logger.error("at method user : %s", e)
So, when I call the url:- http://myserver/api/v1/user_signup
it goes to "user_signup" method of view_user.py file.
But what I want is I should be able validate my request before it goes to the user_signup method.
I want this validation for all the requests that comes to my server for all methods (ex:- user_signup,user_login ...) before it goes to respective methods.

Annotate the concerned views with a decorator that contains the logic you want to execute before the views are called.
See Python - Decorators for a head start.
And How to write a custom decorator in django?
If you want to do this on all requests, regardless of the associated view, then you should consider writing a middleware. See how to setup custom middleware in django

Django work flow redirect from one view to another and display page with url parameter

I am trying to create a web app that users will select a file, get data processed and then redirected to a confirmation page with a url parameter(?status=1) How can I move from the processing view to the confirmation view and then display the confirmation page?
I have put my code below which is not working in my views and urls py files
# views.py
def marketdata_processing(request):
if request.method == 'POST':
uploadform = forms.MyUploadForm(request.POST, request.FILES)
if uploadform.is_valid():
newdoc = models.UploadDocument(docfile=request.FILES['uploadfile'])
filename = request.FILES['uploadfile'].name
newdoc.save()
selecteddate = newdoc.getselecteddate() # Model method calculated
fileid = newdoc.pk
request.session['fileid'] = fileid
request.session['selecteddate'] = selecteddate
return redirect(reverse('views.confirm_input_details'))
else:
uploadform = forms.MyUploadForm()
# Render list page with the documents and the form
return render_to_response(
'mytemplate.html',
{'uploadform': uploadform},
context_instance=RequestContext(request)
)
def confirm_input_details(request):
fileid = request.session['fileid']
selecteddate = request.session['selecteddate']
msg = 'Proceed to import data for %s? \nFileID Being Imported is %s ' % (
selecteddate, fileid,)
url = reverse('views.confirm_input_details', kwargs={'status': 1})
return HttpResponseRedirect(url)
# urls.py
urlpatterns = [
url(r'', views.marketdata_processing, name='myapp/mytemplate.html'),
url(r'^\?status=(?P<status>[0-9]+)$',
views.confirm_input_details, name='myapp/myconfirmpage.html'),
]

There are a couple of issues I feel exist in your code:
Indentation is a very important thing in python code. Please make sure the indentation of your if-else statements in the 'marketdata_processing' view are in correct order. Beware, in your code:
return render_to_response('mytemplate.html',
{'uploadform': uploadform},
context_instance=RequestContext(request))
will always get executed as it is outside the else statement. You might want to indent it under the else (if it makes sense)- like so:
else:
uploadform = forms.MyUploadForm()
return render_to_response('mytemplate.html',
{'uploadform': uploadform},
context_instance=RequestContext(request))
Instead of 'redirect(reverse())' try 'HttpResponseRedirect()' in the processing view to call the confirm-page view, like so:
from django.http import HttpResponseRedirect
return HttpResponseRedirect('/?status=1') --> relative URL shown
place the relative/absolute url (both would work) above.
Finally, render your confirm-page template in the 'confirm_input_details' view with the context parameters, like so:
def confirm_input_details(request):
fileid = request.session['fileid']
selecteddate = request.session['selecteddate']
msg = 'Proceed to import data for %s? \nFileID Being Imported is %s ' % (selecteddate, fileid)
return render_to_response('confirmpage_template.html'),
{'fileid': fileid,
'selecteddate': selecteddate,
'msg': msg}, context_instance=RequestContext(request))
** P.S: Stick to neat basics and it will work. You happened to call your confirm_input_details view from within the same view itself. As far as I think, that would probably take you into an infinite loop. Simple concept of any view is:
take input:request, parameters
--> process logic with parameters
--> render a specific template or call another url where a template is being rendered.
You can't expect a page to show up without the rendering a template.

implementation difficulties in some part of views.py file in django cms

My views.py code:
from django.template import Context, loader, RequestContext
from django.http import HttpResponse
from skey import find_root_tags, count, sorting_list
from search.models import Keywords
def front_page(request):
if request.method == 'get' :
str1 = request.getvalue['word']
fo = open("xml.txt","r")
for i in range(count.__len__()):
file = fo.readline()
file = file.rstrip('\n')
find_root_tags(file,str1,i)
list.append((file,count[i]))
sorting_list(list)
for name, count in list:
s = Keywords(file_name=name,frequency_count=count)
s.save()
fo.close()
return HttpResponseRedirect('/results/')
else :
str1 = ''
list = []
template = loader.get_template('search/front_page.html')
c = RequestContext(request)
response = template.render(c)
return HttpResponse(response)
def results(request):
list1 = Keywords.objects.all()
t = loader.get_template('search/results.html')
c = Context({'list1':list1,
})
return HttpResponse(t.render(c))
#this for everyone.
the flow is this:
1) I run my app on the server .
2)It shows me the search page due to the else part of the view "def front_page(request)", now I want to execute the if part of the view "def front_page(request)" because I want to execute my python code written there and the redirected to the view "def results(request)", how can I do that ?
3) what should I mention in "action" of the front_page.html and in urls.py so that I can get back to the same view again. because I could'nt get back to the same view that I want it is repetitively showing me the same search page.Please help.

To enlarge upon the answer posted by #Barnaby....by using action='#' your form will be posted to the same url as the url used in the get request for the form.
Then in your view code, you have logic that says - if the request for this url is a GET request then do the work to configure the form, otherwise, you assume it is a POST and then you can handle the response.
Additionally I would advise that the your view explicitly checks that the request is a POST and if not make the assumption that it is a GET, rather than the other way around (as you have it), this is safer, as GET and POST are not the only request types, and you definitely need to know that you are dealing with a POST request if you want to deal with variables submitted in the POST request.
Hope that helps

Short answer: action="#". This is a HTML trick to post back to the current URL.
The general answer to how to reference a view in a template is to use the url tag. You may also want to consider using Django's forms functionality.