Django reverse ordering with ListView

Question

I have implemented ordering in a generic ListView:

class CarList(LoginRequiredMixin, ListView):
    model = Car
    paginate_by = 30

    ordering = 'car_id_internal'

    def get_ordering(self):
        return self.request.GET.get('ordering', 'car_id_internal')

    def get_context_data(self, *args, **kwargs):
        context = super(CarList, self).get_context_data(*args, **kwargs)
        context['current_order'] = self.get_ordering()
        return context

And in my template:

<thead>
    <tr>
        <th><a href="{% url 'car_list' %}?ordering=car_id_internal">Internal car ID</a></th>
        <th><a href="{% url 'car_list' %}?ordering=type">Type</a></th>
        <th><a href="{% url 'car_list' %}?ordering=brand">Brand</a></th>
    </tr>
</thead>

This works fine, however I would like for user to be able to reverse the order from ascending to descending when they click on the column header again. Is that possible with Django? I'm using Django 1.9.

I hope someone can help.

NS0 · Accepted Answer · 2016-08-20T22:21:52.590

You need to use another variable for determining the asc/desc ordering. Depending on which is currently selected the template should alternate the links. In the view, you reverse the ordering by adding a dash before the field's name. Try the following:

class CarList(ListView):
    model = Car
    paginate_by = 30

    ordering = 'car_id_internal'
    def get_ordering(self):
        self.order = self.request.GET.get('order', 'asc')
        selected_ordering = self.request.GET.get('ordering', 'car_id_internal')
        if self.order == "desc":
            selected_ordering = "-" + selected_ordering
        return selected_ordering

    def get_context_data(self, *args, **kwargs):
        context = super(CarList, self).get_context_data(*args, **kwargs)
        context['current_order'] = self.get_ordering()
        context['order'] = self.order
        return context

And the template:

<table>
<tr>
    <th><a href="{% url 'car_list' %}?ordering=car_id_internal&order={% if order == 'desc' %}asc{% else %}desc{% endif %}">Internal car ID</a></th>
    <th><a href="{% url 'car_list' %}?ordering=type&order={% if order == 'desc' %}asc{% else %}desc{% endif %}">Type</a></th>
    <th><a href="{% url 'car_list' %}?ordering=brand&order={% if order == 'desc' %}asc{% else %}desc{% endif %}">Brand</a></th>
</tr>
{% for car in object_list %}
<tr>
    <td>{{car.id}}</td>
    <td>{{car.type}}</td>
    <td>{{car.brand}}</td>
</tr>
{% endfor %}

this is refreshes the pages so how to avoid refresh the page??????????????????????????/ — giveJob, May 26 '18 at 13:10
I implemented this solution and it only seems to work one way. Clicking the link a second time does not "reset' or "toggle" the reverse parameter again — Prithvi Boinpally, Nov 16 '19 at 04:58

Django reverse ordering with ListView

1 Answers1