Passing a list through url in django

Question

I want to pass a list through the url. But when i tried, i got some errors. So how can i do that. Somebody please help me..

this is my view

def add_student(request):

    if request.method == 'POST':
        student_list = []
        student_name = request.POST.getlist('student_name')
        student_phone = request.POST.getlist('student_phone')

        zipped = zip(student_name,student_phone)

        for student_name,student_phone in zipped:

            student_object = Student(
                                student_name=student_name,
                                student_phone=student_phone
                            )
            student_object.save()

            student_list.append(student_object.id)

        return HttpResponseRedirect(reverse('students:view_students', args=student_list))
**# in the above code it throwing some errors** 
    else:
        return render(request,'students/add_student.html')


def view_students(request,student_list=None):
    if student_list:
        instances = Student.objects.filter(id__in=student_list)
    else:
        instances = Student.objects.filter()
    context = {}
    context['instances'] = instances

    return render(request,'students/view_all_student.html',context)

this is my url :

url(r'^view-students/(?P<student_list>\w+)/$',views.view_students, name='view_students'),

this is the error i got.

NoReverseMatch at /app/product/add-product/

Reverse for 'view_products' with arguments '(14, 15)' and keyword arguments '{}' not found. 1 pattern(s) tried: [u'app/product/view-products/(?P<pd_list>.*)/$']

here (14,15) are the list items.

If the question is not correct. Somebody please correct the question.

As a general warning, you should be careful about fetching data from request.GET or request.POST and sticking it straight into a filter without validating it. You are allowing the user to view any items from the table that they want, just by tweaking the url or post data. — Alasdair
– Alasdair, Commented Feb 18, 2016 at 16:16
@Alasdair ....thanks...using 'uuid' instead of id. is that a good option??...what is the alternate solution for that??...if you can please let me know — Thameem
– Thameem, Commented Feb 18, 2016 at 17:02
That's too broad a question to answer fully in the comments. UUIDs have the advantage that they are not guessable. Other times, you might have a foreign key, for example from Student to Teacher. Then you would only let the logged in user view students that they currently teach. Other good changes would be to require login for your view, and perhaps restrict access to users with a 'view students' permission. — Alasdair
– Alasdair, Commented Feb 18, 2016 at 17:13

Sayse · Accepted Answer · 2016-02-18 16:08:18Z

3

If all you want to do is render a list you should just do that.

def add_student(request):
    if request.method == 'POST':
        student_list = []
        student_name = request.POST.getlist('student_name')
        student_phone = request.POST.getlist('student_phone')

        zipped = zip(student_name,student_phone)

        for student_name,student_phone in zipped:
            student = Student.objects.create(student_name=student_name,
                                             student_phone=student_phone)
            student_list.append(student)

        return render(request,'students/view_all_student.html', {'instances': student_list})
    else:
        return render(request,'students/add_student.html')

However, Your issue seems to be concerned with users double posting this request. To remedy this you could pass them as a get parameter

def add_student(request):
    if request.method == 'POST':
        student_list = []
        student_name = request.POST.getlist('student_name')
        student_phone = request.POST.getlist('student_phone')

        zipped = zip(student_name,student_phone)

        for student_name,student_phone in zipped:
            student = Student.objects.create(student_name=student_name,
                                             student_phone=student_phone)
            student_list.append(str(student.id))

        redirect = HttpResponseRedirect(reverse('students:view_students'))
        redirect['Location'] += '&'.join(['students={}'.format(x) for x in student_list]))
        return redirect
    else:
        return render(request,'students/add_student.html')

def view_students(request):
    students = request.GET.getlist('students')
    if students:
        students = [int(x) for x in students]
        instances = Student.objects.filter(id__in=students)

edited Feb 18, 2016 at 16:08

answered Feb 18, 2016 at 14:11

Sayse

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11 Comments

Thameem Over a year ago

thanks for your answer.. i have experienced some problem when i try to do as you mentioned , whenever i refresh the page ,all the data is stored in the database again..

Anentropic Over a year ago

Yes it is good practice to redirect after a POST request, to avoid the user double-posting the data if they refresh the page.

Alasdair Over a year ago

If you have ?students=23,24,25,26 in the URL, then you want students = request.GET.get('students') instead of getlist. Then convert to a list of integers with sd_list = [int(x) for x in students.split(',').

Sayse Over a year ago

@Thameem - (and all), I've changed the way that the get params are constructed to use the other notation which should fix your issues. Apologies for not testing further! (Thanks Anentropic and Alasdair)

Alasdair Over a year ago

In my comment above, it should be students = request.GET.get('students', ''), otherwise students.split(',') will throw an error when the key isn't in request.GET.

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