[Django]-Paginating the results of a Django forms POST request

Reading the very nice answer from tux21b I decided to implement the first option, i.e., to use the session to store the query. This is an application that searches real estate databases. Here is the view code (using django 1.5):

def main_search(request):
    search_form = UserSearchForm()
    return render(request, 'search/busca_inicial.html', {'search_form': search_form})


def result(request):
    if request.method == 'POST':
        search_form = UserSearchForm(request.POST)
        if search_form.is_valid():
            # Loads the values entered by the user on the form. The first and the second
            # are MultiChoiceFields. The third and fourth are Integer fields
            location_query_list = search_form.cleaned_data['location']
            realty_type_query_list = search_form.cleaned_data['realty_type']
            price_min = search_form.cleaned_data['price_min']
            price_max = search_form.cleaned_data['price_max']
            # Those ifs here populate the fields with convenient values if the user
            # left them blank. Basically the idea is to populate them with values
            # that correspond to the broadest search possible.
            if location_query_list == []:
                location_query_list = [l for l in range(483)]
            if realty_type_query_list == []:
                realty_type_query_list = [r for r in range(20)]
            if price_min == None:
                price_min = 0
            if price_max == None:
                price_max = 100000000
            # Saving the search parameters on the session
            request.session['location_query_list'] = location_query_list
            request.session['price_min'] = price_min
            request.session['price_max'] = price_max
            request.session['realty_type_query_lyst'] = realty_type_query_list
    # making a query outside the if method == POST. This logic makes the pagination     possible.
    # If the user has made a new search, the session values would be updated. If not,
    # the session values will be from the former search. Of course, that is what we want  because
    # we want the 'next' and 'previous' pages correspond to the original search
    realty_list_result =    FctRealtyOffer.objects.filter(location__in=request.session['location_query_list']
                                                    ).filter(price__range=(request.session['price_min'], request.session['price_max'])
                                                   ).filter(realty_type__in=request.session['realty_type_query_lyst'])
    # Here we pass the list to a table created using django-tables2 that handles sorting
    # and pagination for us
    table = FctRealtyOfferTable(realty_list_result)
    # django-tables2 pagination configuration
    RequestConfig(request, paginate={'per_page': 10}).configure(table)

    return render(request, 'search/search_result.html', {'realty_list_size': len(realty_list_result),
                                                      'table': table})

Hope it helps!If anyone has any improvement to suggest, be welcome.

As @rvnovaes, a way to use session to solve the matter.

The drawback of his solution is that if there are many search fields you have to write many lines of code, and also if you show the search form in the result page, all the fields will be blank, while they should keep their values.

So I’d rather save all the post data in session, and at the beginning of the view force the value of request.POST and request.method if a session is defined:

""" ... """
if not request.method == 'POST':
    if 'search-persons-post' in request.session:
        request.POST = request.session['search-persons-post']
        request.method = 'POST'

if request.method == 'POST':
    form = PersonForm(request.POST)
    request.session['search-persons-post'] = request.POST
    if form.is_valid():
        id = form.cleaned_data['id']
""" ... """

More info here

I did this in my web application with get parameters Maybe i can help you :

Views.py

class HomeView(ListView):
model = Hotel
template_name = 'index.html'
paginate_by = 10  # if pagination is desired

def get_queryset(self):
   qs = super().get_queryset()
   kwargs = {}
   if 'title' in self.request.GET:
       title = self.request.GET.get('title')
       if title != '':
           kwargs['title__icontains'] = title
   if 'category' in self.request.GET:
       category = self.request.GET.get('category')
       if category:
           kwargs['category_id'] = category
   if 'size' in self.request.GET:
       size = self.request.GET.get('size')
       if size:
           kwargs['size_id'] = size
   if 'service' in self.request.GET:
       service = self.request.GET.get('service')
       if service:
           kwargs['service_id'] = service
   if 'ownership' in self.request.GET:
       ownership = self.request.GET.get('ownership')
       if ownership:
           kwargs['ownership_id'] = ownership
   qs = qs.filter(**kwargs)
   return qs

def get_context_data(self, **kwargs):
    context = super().get_context_data(**kwargs)
    form_init = {}
    form = SearchForm()
    if self.request.GET.items():
        try:
            parameters = self.request.GET.items()
        except KeyError:
            parameters = {}
        for key, value in parameters:
            for field in form.fields:
                if key == field:
                    form_init[key] = value
        form.initial = form_init
    if 'title' in self.request.GET:
       title = self.request.GET.get('title')
       if title != '':
           context.update({
            'title': title
           })
    if 'category' in self.request.GET:
       category = self.request.GET.get('category')
       context.update({
        'category': category
       })
    if 'size' in self.request.GET:
       size = self.request.GET.get('size')
       context.update({
           'size': size
      })
    if 'service' in self.request.GET:
       service = self.request.GET.get('service')
       context.update({
           'service': service
      })
    if 'ownership' in self.request.GET:
       ownership = self.request.GET.get('ownership')
       context.update({
          'ownership': ownership
       })
    context.update({
        'search_form': form
    })
    return context

Pagination file html

<div class="row">
  {% if is_paginated %}
  <nav aria-label="...">
    <ul class="pagination">
      {% if page_obj.has_previous %}
        <li class="page-item"><a class="page-link" href="?category={{category}}&size={{size}}&service={{service}}&ownership={{ownership}}&page={{ page_obj.previous_page_number }}">Previous</a></li>
      {% else %}
        <li class="page-item disabled"><span class="page-link">Previous</span></li>
      {% endif %}
      <span class="page-current">
               Page {{ page_obj.number }} of {{ page_obj.paginator.num_pages }}.
           </span>
      {% if page_obj.has_next %}
        <li class="page-item"><a class="page-link" href="?category={{category}}&size={{size}}&service={{service}}&ownership={{ownership}}&page={{ page_obj.next_page_number }}">Next</a></li>
      {% else %}
        <li class="page-item disabled"><span class="page-link">Next</span></li>
      {% endif %}
    </ul>
  </nav>
 {% endif %}
</div>

You can ask request object if it’s ajax, simply request.is_ajax. This way you can detect, whether it’s first post request or further questions about the next pages.

Have the search form and the results display on one single django template. Initially, use css to hide the results display area. On POSTing the form, you could check to see if the search returned any results and hide the search form with css if results exist. If results do not exist, use css to hide the results display area like before. In your pagination links, use javascript to submit the form, this could be as simple as document.forms[0].submit(); return false;

You will need to handle how to pass the page number to django’s paging engine.

My suggestion would be to store the post request using a session or a cookie. In case the post data is sensitive, you should use session to store it. The code below contains my logic to implement it using session.

def index(request):
    is_cookie_set = 0
    # Check if the session has already been created. If created, get their values and store it.
    if 'age' in request.session and 'sex' in request.session: 
        age = request.session['age']
        sex = request.session['sex']
        is_cookie_set = 1
    else:
        # Store the data in the session object which can be used later
        request.session['age'] = age
        request.session['sex'] = sex
    if(request.method == 'POST'):
        if(is_cookie_set == 0): # form submission by the user
            form = EmployeeForm(request.POST)
            sex = form.cleaned_data['sex']
            age = form.cleaned_data['age']
            if form.is_valid():
                result = Employee.objects.all(sex=sex,age_gte=age) # filter all employees based on sex and age
        else: # When the session has been created
            result = Employee.objects.all(sex=sex,age_gte=age)
        paginator = Paginator(result, 20) # Show 20 results per page
        page = request.GET.get('page')
        r = paginator.get_page(page)
        response = render(request, 'app/result.html',{'result':result})    
        return response
    else:
        form = EmployeeForm()
    return render(request,'app/home.html',{'form':form})

You should also check if the post fields are empty or not and change the logic according to it. You can also store the whole post request in the session as suggested by @abidibo.

You can also use cookies for the same. I have explained it here

The Below code is working, the first request is a GET request, which accesses the form, will go directly to the else block.
Once the user puts up a search query, results will be shown, which will be a post request, and 2nd if block will be activated, this request we will store in a session.
When the user accesses 2nd search page, it will be a GET request, but we are checking whether there is an active pagination session, and also checking whether it’s not a page request of GET. At this point 1st if block will be trigerred.

def search(request):
    if not request.method == "POST" and 'page' in request.GET:
    if 'search-query' in request.session:
        request.POST = request.session['search-query']
        request.method = 'POST'

    if request.method == 'POST':
    form = Search_form(request.POST)
    request.session['search-query'] = request.POST
    if form.is_valid():
        search_query = form.cleaned_data.get('search_query')
        search_parameter = form.cleaned_data.get('search_parameter')
        print(search_query, search_parameter)
        queryset_list = CompanyRecords.objects.filter(**{f'{search_parameter}__icontains': search_query}).exclude(
            company_name__isnull=True).exclude(description__isnull=True).exclude(phones__isnull=True).exclude(
            emails__isnull=True)[:5]
        page = request.GET.get('page', 1)
        paginator = Paginator(queryset_list, 2)

        try:
            queryset = paginator.page(page)
        except PageNotAnInteger:
            queryset = paginator.page(1)
        except EmptyPage:
            queryset = paginator.page(paginator.num_pages)

        return render(request, 'search/search_results.html', {'queryset': queryset})

    else:
    context = {
        'form': Search_form()
    }
    return render(request, 'search/search.html', context)