Code-It » django

django-wkhtmltopdf on a linux (Webfaction) server

Loïs Di Qual — Tue, 04 Sep 2012 13:10:08 +0000

Generating PDF with python is not an easy thing. Here is what I’ve tried:

xhtml2pdf: the worst. It has a very bad CSS interpreter and it is pretty impossible to make a clean PDF out from a complex html page.
WeasyPrint: that’s better. It has its own HTML and CSS2 interpreters, and despite some minor issues it is fairly reliable. However it requires some big dependencies, and I eventually had some memory issues on my webserver.
wkhtmltopdf with its Django wrapper: for now, the best. It makes use of Webkit to render HTML+CSS+JS(!) pages, I don’t think you can do better. However, it requires QT, and this is big. Well, not the “classical” QT, a patched QT (that’s even worse) that allows to run without an X server. This is what I’m using for now in my projects

We’ll see here how to build wkhtmltopdf and a basic django-wkhtmltopdf usage. These steps has been tested on a Webfaction server (CentOS 6) through SSH.

The easy way

Enter this command and go to the “Post-install” chapter.

1	curl -fsSkL https://raw.github.com/gist/3608048/wkhtmltopdf.sh \| sh

It will install wkhtmltopdf in ~/bin with its static libraries.

The hard way – Let’s build this

This is mostly taken from the wkhtmltopdf Wiki, but with some no-shared-libraries webserver specifics. Log on SSH, and let the magic begin.

Create a ~/download folder

1 2	$ mkdir -p ~/downloads $ cd ~/downloads

Get wkhtmltopdf-qt:

1
2
3
4

$ git clone git://gitorious.org/+wkhtml2pdf/qt/wkhtmltopdf-qt.git wkhtmltopdf-qt
$ cd wkhtmltopdf-qt
$ git checkout staging
$ QTDIR=. ./bin/syncqt

Configure, and build it! It will take some time (about an hour, which is not much as we disabled a lot of features):

1
2
3

$ ./configure -release -static -fast -exceptions -no-accessibility -no-stl -no-sql-ibase -no-sql-mysql -no-sql-odbc -no-sql-psql -no-sql-sqlite -no-sql-sqlite2 -no-qt3support -xmlpatterns -no-phonon -no-phonon-backend -webkit -no-scripttools -no-mmx -no-3dnow -no-sse -no-sse2 -qt-zlib -qt-libtiff -qt-libpng -qt-libmng -qt-libjpeg -graphicssystem raster -opensource -nomake tools -nomake examples -nomake demos -nomake docs -nomake translations -no-opengl -no-dbus -no-multimedia -openssl -no-declarative -largefile -rpath -no-nis -no-cups -no-iconv -no-pch -no-gtkstyle -no-nas-sound -no-sm -no-xshape -no-xinerama -no-xcursor -no-xfixes -no-xrandr -no-mitshm -no-xinput -no-xkb -no-glib -no-openvg -no-xsync -no-audio-backend -no-sse3 -no-ssse3 -no-sse4.1 -no-sse4.2 -no-avx -no-neon -confirm-license -prefix "../wkqt"
$ gmake -j3
$ gmake install

Then, download wkhtmltopdf, and build it:

1
2
3
4
5

$ cd ~/downloads
$ git clone git://github.com/antialize/wkhtmltopdf.git wkhtmltopdf
$ cd wkhtmltopdf
$ ../wkqt/bin/qmake
$ make

You now have wkhtmltopdf and its static dependencies in ./bin/. Let’s copy them into ~/bin:

1 2	$ mkdir -p ~/bin $ cp bin/* ~/bin/

Post-installation

We need ~/bin in our $PATH. That’s where django-wkhtmltopdf will look for. Add the following line in your ~/.bashrc.

1 2	export PATH=$HOME/bin:$PATH export LD_LIBRARY_PATH=$HOME/lib:$LD_LIBRARY_PATH

And source it:

1	$ source ~/.bashrc

We’re done with wkhtmltopdf, let’s install its Django wrapper.

django-wkhtmltopdf

Go to your django app, and install django-wkhtmltopdf with PIP:

1	$ pip install wkhtmltopdf

Then, in your view:

1
2
3
4

from wkhtmltopdf.views import PDFTemplateResponse

def view(request):
PDFTemplateResponse(request, template_name, context_dictionary).rendered_content

Be careful, this last line of code is not documented in the django-wkhtmltopdf’s wiki. It may be subject to changes in future releases. However, that’s the only way I found to get a binary-string instead of a HttpResponse.

That’s all, folks !

Django – UnicodeDecodeError using i18n

Loïs Di Qual — Mon, 30 Jul 2012 21:32:11 +0000

If you’re using i18n in your django website, you may encounter this issue. It took me two hours to find where the problem came from: you have to use ugettext instead of gettext if your translated strings contains non-ascii characters.

gettext => ugettext

With gettext:

1
2
3
4
5

from django.utils.translation import gettext as _

define my_view(request):
print _("Here comes nothing") // Prints "Here comes nothing"
print _("Here comes something spécial") // Raises a UnicodeDecodeError because "é" is not unicode

With ugettext:

1
2
3
4
5

from django.utils.translation import ugettext as _

define my_view(request):
print _("Here comes nothing") // Prints "Here comes nothing"
print _("Here comes something spécial") // Prints "Here comes something spécial"

ugettext or ugettext_lazy ?

Two simple rules:

Use ugettext_lazy in global scopes (model fields, django settings, everything not wrapped by a function or method, …)
Use ugettext everywhere else (in views, methods, functions, …)

That’s it !

Django – Absolute media URIs from templates

Loïs Di Qual — Mon, 16 Jul 2012 21:54:17 +0000

Sometimes, you need to build an absolute URI to a media file from your templates:

1	http://example.com/media/sample.jpg

After following this small tutorial, you’ll be able to do this:

1 2	{% load mytemplatetags %} {{ media_name\|absolute_media_url:request }}

Settings

In urls.py, in urlpatterns, add a reverse name to the media URL:

1
2
3
4
5
6

urlpatterns = patterns('',
# Before
(r'^media/(?P.*)$', 'django.views.static.serve', {'document_root': settings.MEDIA_ROOT}),
# After
url(r'^media/(?P.*)$', 'django.views.static.serve', {'document_root': settings.MEDIA_ROOT}, name="media"),
)

You can now reverse media files using request.build_absolute_uri(reverse('media', args=['/path/to/media'])).

In settings.py, add django.core.context_processors.request to TEMPLATE_CONTEXT_PROCESSORS.

This context processor allows you to access the request.build_absolute_uri() function from templates:

1	{{ request.build_absolute_uri }}

However, you can’t pass parameters to this function, so you won’t be able to reverse media path to URL. That’s why we need a filter.

Absolute url for a media

The following filter will allow you to build an absolute URL to a media. In templatetags/mytemplatetags.py:

1
2
3
4
5
6

'''
Usage: {{ media|absolute_media_url:request }}
'''
@register.filter
def absolute_media_uri(media, request):
return request.build_absolute_uri(reverse('media', args=[unicode(media)]))

Don’t forget to add a blank __init__.py in templatetags/ or django won’t take your template tag into account.