Author: John Au-Yeung

To download a file with Python Django, we can return a response with the download file.

For instance, we write

import os
from django.conf import settings
from django.http import HttpResponse, Http404

def download(request, path):
    file_path = os.path.join(settings.MEDIA_ROOT, path)
    if os.path.exists(file_path):
        with open(file_path, 'rb') as fh:
            response = HttpResponse(fh.read(), content_type="application/vnd.ms-excel")
            response['Content-Disposition'] = 'inline; filename=' + os.path.basename(file_path)
            return response
    raise Http404

to create the download view that gets the file from file_path if it exists.

We call open to open the file.

And the we create a HttpResponse with the Content-Disposition header set.

We set the content_type when we create the HttpResponse to the MIME type of the file downloaded.

And fh.read() has the download file content.

Then we return the response.

If the file isn’t found, then we return a 404 error with raise Http404.

To reference list item by index within Python Django template, we can create our own filter.

For instance, we write

from django import template
register = template.Library()

@register.filter
def index(indexable, i):
    return indexable[i]

to create the index filter by applying @register.filter decorator to the index function in templatetags/index.py.

Then in our templaye, we use it by writing

{% load index %}
{{ my_list|index:x }}

{{ my_list|index:forloop.counter0 }}

to use the index decorator after loading it by using the index as its argument

To set cookies with Python Django, we can use set_cookie and request.COOKIES.

For instance, we write

def view(request):
  response = HttpResponse('blah')
  response.set_cookie('cookie_name', 'cookie_value')

to call response.set_cookie with the cookie name and value.

And then we get the cookie by writing

def view(request):
  value = request.COOKIES.get('cookie_name')
  if value is None:
    # Cookie is not set

to call request.COOKIES.get with the cookie name to get the cookie.

To add URL parameters to Python Django template url tag, we can add them after the URL name.

For instance, we write

url(r'^panel/person/(?P<person_id>[0-9]+)$', 'apps.panel.views.person_form', name='panel_person_form'),

to add a URL with url.

And then we add the parameter by writing

{% url 'panel_person_form' person_id=item.id %}

to add the person_id parameter after the URL name.

We separate multiple parameters with spaces.

To redirect a post and pass on the post data with Python Django, we can redirect with HttpResponseRedirect.

For instance, we write

def some_view(request):
    #do some stuff
    request.session['_old_post'] = request.POST
    return HttpResponseRedirect('next_view')

def next_view(request):
    old_post = request.session.get('_old_post')
    #do some stuff using old_post

to create 2 views some_view and next_view.

In some_view, we return the HttpResponseRedirect response to redirect to next_view.

And in next_view we get the _old_post value from request.session that we saved in some_view.

And then we do stuff with the value.