Fallback for Django view that relies on session variable

Question

I have a view that looks like this:

def CineByCiudad(request):
    city = request.session["ciudad"]
    cines = Cine.objects.filter(ciudad=city)
    context = {'cines': cines}
    return render_to_response('cine-ciudad.html', context, context_instance=RequestContext(request))

Now, I am using the session variable "ciudad" to filter my query. On the homepage of my site I let the user set their "ciudad" and once its set I redirect them to another page and they can start viewing the content based on their city("ciudad").

My homepage checks if the session has items:

def index(request):
    #Checks to see if the session has items, in particular if a city has been set
    if not request.session.items():
        return render_to_response('index.html', context_instance=RequestContext(request))
    else:
        return redirect(Cartelera)

Now lets suppose for some reason the user deletes his cookies and on the site he visits a url different than the homepage(something like www.site.com/cartelera) he would then get an error because the session variable "ciudad" is not set.

Is there a way to create a default value for this session variable in case that it has not been set? Or what is a good practice to deal with this issue?

Answer 1

Use the dict.get method on the session to retrieve a default if the value isn't set, like this:

city = request.session.get('ciudad', 'default value')