How to write Django 'if then else' statement logic

I have a homepage which currently runs a forloop to show all users.

{% for user in users %}

On that same page, there is a form to filter by radius (km) to see users close to you.

Currently, after you submit a radius to filter the users, nothing is returned because there is no

{% for user in location %} forloop yet.

I know I need some

{% if xxx %} {% else %} {% endif %}

statements but I'm unsure how to write them.

Essentially, if no filter is selected / radius is submitted I want to return all users (like it does right now). But if a radius is submitted or a filter is applied, I want the page to return the results of the queryset / multiple querysets.

Many thanks and any suggestions on cleaning up my code are always appreciated as I am a beginner.

views.py

class ConnectView(View):
    template_name = 'connect/home.html'
    def get(self, request, *args, **kwargs):
        context = {
            'users': User.objects.exclude(username=request.user),
            'friends': Friend.objects.filter(current_user=request.user),
        }
        return render(request, self.template_name, context)

    def post(self, request, *args, **kwargs):
        location = Location(latitude=request.POST['latitude'], longitude=request.POST['longitude'], user = request.user)
        location.save()
        return JsonResponse({'message': 'success'})

def location(request):
    if request.POST:
        radius_km = request.POST.get('radius', 0)
        queryset = User.objects.annotate(
            radius_sqr=pow(models.F('loc__latitude') -
            request.user.loc.latitude, 2) + pow(models.F('loc__longitude') -
            request.user.loc.longitude, 2)
            ).filter(
            radius_sqr__lte=pow(int(radius_km) / 9, 2)
            ).exclude(username=request.user)
        context = dict(location=queryset)
        return render(request, 'connect/home.html', context)

urls.py

urlpatterns = [
    path('', connect_views.ConnectView.as_view(), name='connect_home'),
    path('location', connect_views.location, name='location'),

connect.html

  <h1>Connect with people near you.</h1>
            <!-- GET window.location IP Address / lat lon coordinates -->
            <p id="demo"></p>
            <button onclick="getLocation()" class="btn btn-warning" id="confirm">1. Fetch Location</button>
            <button type="submit" id="btn_submit" class="btn btn-success" disabled>2. Submit Location </button>
            <!-- enter radius to filter by location -->
            <form action="location" method="POST">
              {% csrf_token %}
              <input type="number" name="radius">
              <input type="submit" value="filter by kilometers">
            </form>

{% for user in users %}
       <h4>{{ user.first_name }} {{ user.last_name }}
       {{ user.profile.age }} / {{ user.profile.city }}
       {{ user.profile.bio }}</h4>
{% endfor %}