This slide is an introduction of "The Django Book" chapter #13 in Taipei.Py, Aug. 20, 2013.

1. Generating Non-HTML Content
Django Meetup
Johnny Wang
Aug. 20, 2013

2. A Simple Example...
● A simple non-HTML example: loading an
image
from django.http import HttpResponse
def my_image(request):
image_data = open("/path/to/my/image.png", "rb").read()
return HttpResponse(image_data, mimetype="image/png")

3. Generating CSV files
import csv
from django.http import HttpResponse
UNRULY_PASSENGERS = [146,184,235,200,226,251,299,273,281,304,203]
def unruly_passengers_csv(request):
response = HttpResponse(mimetype='text/csv')
response['Content-Disposition'] = 'attachment; filename=unruly.csv'
writer = csv.writer(response)
writer.writerow(['Year', 'Unruly Airline Passengers'])
for (year, num) in zip(range(1995, 2006), UNRULY_PASSENGERS):
writer.writerow([year, num])
return response

4. PDF Open Source Library
pip install reportlab

5. PDF Hello World
from reportlab.pdfgen import canvas
from django.http import HttpResponse
def hello_pdf(request):
# Create the HttpResponse object with the appropriate PDF headers.
response = HttpResponse(mimetype='application/pdf')
response['Content-Disposition'] = 'attachment; filename=hello.pdf'
# Create the PDF object, using the response object as its "file."
p = canvas.Canvas(response)
# Draw things on the PDF. Here's where the PDF generation happens.
p.drawString(100, 100, "Hello world.")
# Close the PDF object cleanly, and we're done.
p.showPage()
p.save()
return response

6. PDF Hello World (w. cStringIO)
from cStringIO import StringIO
from reportlab.pdfgen import canvas
from django.http import HttpResponse
def hello_pdf(request):
# Create the HttpResponse object with the appropriate PDF headers.
response = HttpResponse(mimetype='application/pdf')
response['Content-Disposition'] = 'attachment; filename=hello.pdf'
temp = StringIO()
p = canvas.Canvas(temp)
p.drawString(100, 100, "Hello world. (w. StringIO)")
p.showPage()
p.save()
# Get the value of the StringIO buffer and write it to the
response.
response.write(temp.getvalue())
return response

7. Others Format Libraries
● ZIP files
– zipfile
– tarfile
● Dynamics images
– PIL
● Plots and charts
– matplotlib
– pygraphviz

8. Site Map

9. SiteMap Installation
● settings.py
– Add 'django.contrib.sitemaps' into
INSTALLED_APPS
– Make sure that
'django.template.loaders.app_directories.load_tem
plate_source' is in your TEMPLATE_LOADERS
setting

10. SiteMap Initialization
● urls.py
(r'^sitemap.xml$', 'django.contrib.sitemaps.views.sitemap',
{'sitemaps': sitemaps})
● File name is not important, but the location is.

11. SiteMap Class Structure
● items (required)
– Doesn't care about the type
● location (optional)
– “absolute URL”
● Good: '/foo/bar/'
● Bad: 'example.com/foo/bar/'
● Bad: 'http://example.com/foo/bar/'
– Default: calling get_absolute_url() on each object

12. SiteMap Class Structure (ctn')
● lastmod (optional)
– The object’s “last modification” date
● changefreq (optional)
– How often the object changes.
● 'always', 'hourly', 'daily', 'weekly', 'monthly', 'yearly',
'never'
● priority (optional)
– Value is between 0.0 ~ 1.0 (default: 0.5)

13. A Sitemap Class Example
from django.contrib.sitemaps import Sitemap
from mysite.blog.models import Entry
class BlogSitemap(Sitemap):
changefreq = "never"
Priority = 0.5
def items(self):
return Entry.objects.filter(is_draft=False)
def lastmod(self, obj):
return obj.pub_date

14. Pinging Google
● To make Google reindex your sitemap
● django.contrib.sitemaps.ping_google()
– sitemap_url (optional)
● Should be the absolute URL of your sitemap.xml
● Usually we use save() method to call
ping_google():

15. save() for ping_google()
from django.contrib.sitemaps import ping_google
class Entry(models.Model):
# ...
def save(self, *args, **kwargs):
super(Entry, self).save(*args, **kwargs)
try:
ping_google()
except Exception:
# Bare 'except' because we could get a variety
# of HTTP-related exceptions.
pass

16. Thank You