How to use the ta.models.TAApplication.objects.filter function in ta

if person.sin() != person.defaults['sin']:
            sin = person.sin()
       
    if request.method == "POST":
        search_form = StudentSearchForm(request.POST)
        #Try to manually retrieve person
        if manual:
            try:
                person = get_object_or_404(Person, emplid=int(request.POST['search']))
            except ValueError:
                search_form = StudentSearchForm(request.POST['search'])
                messages.error(request, "Invalid emplid %s for person." % (request.POST['search']))
                return HttpResponseRedirect(reverse('ta:new_application_manual', args=(post_slug,)))
            
            #Check to see if an application already exists for the person 
            existing_app = TAApplication.objects.filter(person=person, posting=posting)
            if existing_app.count() > 0: 
                messages.success(request, "%s has already applied for the %s %s posting." % (person, posting.unit, posting.semester))
                return HttpResponseRedirect(reverse('ta:view_application', kwargs={'post_slug': existing_app[0].posting.slug, 'userid': existing_app[0].person.userid}))
        
        if editing:
            ta_form = TAApplicationForm(request.POST, request.FILES, prefix='ta', instance=application)
        else:
            ta_form = TAApplicationForm(request.POST, request.FILES, prefix='ta')

        ta_form.add_extra_questions(posting)

        courses_formset = CoursesFormSet(request.POST)
        for f in courses_formset:
            f.fields['course'].choices = course_choices

        if ta_form.is_valid() and courses_formset.is_valid():

def print_all_applications(request,post_slug):
    posting = get_object_or_404(TAPosting, slug=post_slug, unit__in=request.units)
    applications = TAApplication.objects.filter(posting=posting).order_by('person')

    for application in applications:
        application.courses = CoursePreference.objects.filter(app=application).exclude(rank=0).order_by('rank')
        application.skills = SkillLevel.objects.filter(app=application).select_related('skill')
        application.campuses = CampusPreference.objects.filter(app=application)
        application.contracts = TAContract.objects.filter(application=application)
        application.previous_experience = TACourse.objects.filter(contract__application__person=application.person) \
            .exclude(contract__application=application).select_related('course__semester')
        application.grad_programs = GradStudent.objects \
             .filter(program__unit__in=request.units, person=application.person)

    context = {
            'applications': applications,
            'posting': posting,
            }
    return render(request, 'ta/print_all_applications.html', context)

if not manual:
        """
        Don't change the person in the case of a TA Admin editing, as we don't want to save this application as the
        Admin's, but as the original user's.
        """
        if not is_ta_admin:
            try:
                person = ensure_person_from_userid(request.user.username)
            except SIMSProblem:
                return HttpError(request, status=503, title="Service Unavailable", error="Currently unable to handle the request.", errormsg="Problem with SIMS connection while trying to find your account info")

        if not person:
            return NotFoundResponse(request, "Unable to find your computing account in the system: this is likely because your account was recently activated, and it should be fixed tomorrow. If not, email %s." % (help_email(request),))

        existing_app = TAApplication.objects.filter(person=person, posting=posting)
        if not userid and existing_app.count() > 0: 
            messages.success(request, "You have already applied for the %s %s posting." % (posting.unit, posting.semester))
            return HttpResponseRedirect(reverse('ta:view_application', kwargs={'post_slug': existing_app[0].posting.slug, 'userid': existing_app[0].person.userid}))

        if person.sin() != person.defaults['sin']:
            sin = person.sin()
       
    if request.method == "POST":
        search_form = StudentSearchForm(request.POST)
        #Try to manually retrieve person
        if manual:
            try:
                person = get_object_or_404(Person, emplid=int(request.POST['search']))
            except ValueError:
                search_form = StudentSearchForm(request.POST['search'])
                messages.error(request, "Invalid emplid %s for person." % (request.POST['search']))

# generate CSV
    filename = str(posting.slug) + '.csv'
    response = HttpResponse(content_type='text/csv')
    response['Content-Disposition'] = 'inline; filename="%s"' % (filename)
    csvWriter = csv.writer(response)
    
    #First csv row: all the course names
    off = ['Rank', 'Name', 'Categ', 'Program (Reported)', 'Program (System)', 'Status', 'Unit', 'Start Sem', 'BU',
           'Campus', 'Assigned Course(s)', 'Assigned BUs'] + [str(o.course) + ' ' + str(o.section) for o in offerings]
    csvWriter.writerow(off)
    
    # next row: campuses
    off = ['']*12 + [str(CAMPUSES_SHORTENED[o.campus]) for o in offerings]
    csvWriter.writerow(off)
    
    apps = TAApplication.objects.filter(posting=posting).order_by('person')
    for app in apps:
        rank = 'P%d' % app.rank
        system_program = ''
        startsem = ''
        status = ''
        unit = ''
        # grad program info
        gradstudents = GradStudent.get_canonical(app.person, app.posting.semester)
        if len(gradstudents) == 1:
            gs = gradstudents[0]
            system_program = gs.program.label
            status = gs.get_current_status_display()
            unit = gs.program.unit.label
            if gs.start_semester:
                startsem = gs.start_semester.name
            else:

def new_contract(request, post_slug):
    """
    Create a new contract for this person and redirect to edit it.
    """
    posting = get_object_or_404(TAPosting, slug=post_slug, unit__in=request.units)

    existing = set(c.application_id for c in TAContract.objects.filter(posting=posting).select_related('application'))
    queryset = TAApplication.objects.filter(posting=posting).exclude(id__in=existing).order_by('person')
    application_choices = [(a.id, a.person.name()) for a in queryset if a not in existing]
    
    if request.method == 'POST':
        form = NewTAContractForm(request.POST)
        form.fields['application'].choices = application_choices
        form.fields['application'].queryset = queryset
        
        if form.is_valid():
            app = form.cleaned_data['application']
            contract = TAContract(created_by=request.user.username)
            contract.first_assign(app, posting)
            return HttpResponseRedirect(reverse('ta:edit_contract', kwargs={'post_slug': posting.slug, 'userid': app.person.userid}))
    
    return HttpResponseRedirect(reverse('ta:all_contracts', args=(post_slug,)))

def download_all_applications(request, post_slug):
    posting = get_object_or_404(TAPosting, slug=post_slug, unit__in=request.units)
    applications = TAApplication.objects.filter(posting=posting)
    response = HttpResponse(content_type='text/csv')

    response['Content-Disposition'] = 'inline; filename="ta_applications-%s-%s.csv"' % \
                                      (posting.semester.name, datetime.datetime.now().strftime('%Y%m%d'))
    writer = csv.writer(response)
    if applications:
        writer.writerow(['Person', 'ID', 'Category', 'Program', 'Assigned BUs', 'Max BUs', 'Ranked', 'Assigned', 'Campus Preferences'])

        for a in applications:
            writer.writerow([a.person.sortname(), a.person.emplid, a.get_category_display(), a.get_current_program_display(), a.base_units_assigned(),
                             a.base_units, a.course_pref_display(), a.course_assigned_display(), a.campus_pref_display()])
    return response