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Generate office documents with Django

In our recent Django projects, we had to create documents (Libre/OpenOffice, Microsoft Office, PDF...), and therefore created two components :

django-appypod

Appy is a set of python tools (e.g. framework) by Gaetan Delannay, which provides, among other stuff, a templating engine for OpenDocument files.

One the great advantage is that you edit your templates in LibreOffice, WYSIWYG !

django-appypod is a template view that renders a OpenDocument template for a context. The exact same way you already do for HTML.

Using class-based generic views :

from django.view.generic.detail import TemplateView

from djappypod.response import OdtTemplateResponse


class YourDocument(TemplateView):
    response_class = OdtTemplateResponse
    template_name = "your/template.odt"

    def get_context_data(self, **kwargs):
        kwargs['title'] = 'Simple as hello ;)'
        return kwargs

Using classic functions-based views :

def your_view(request):
    context = {
        'title': 'Simple as hello ;)'
    }
    response = OdtTemplateResponse(request, "your/template.odt", context)
    response.render()
    return response

ConvertIt

We often need to serve those document as PDF files, and some users can't be satisfied with OpenDocument files.

Appy can rely on OpenOffice to convert documents to PDF and MS-Word, but we didn't like the idea of having to install the bunch of binaries along every Django project. Therefore we created ConvertIt, a Web API that will just be in charge of format conversion. It can live on a dedicated server, and thus isolate binaries, and potentially convert from and to any exotic formats, relying on any exotic system binaries.

So far we implemented most office documents conversions (.pdf, .doc, .xls), as well as SVG to PDF and PNG.

Docker image

If you use Docker, you can get a ConvertIt instance running in one command :

sudo docker run -p :6543 makinacorpus/convertit

Manual installation

It is a Pyramid project, pretty straightforward :

pip install convertit

Plus some conversion binaries (each one is optional):

sudo apt-get install -y libreoffice unoconv inkscape

To run a development instance :

pserve development.ini --reload

To run a production instance :

pip install gunicorn
gunicorn --paste production.ini

Usage

Using GET requests :

curl http://convertit/?url=http://server/document.odt&to=application/pdf
HTTP/1.1 302 Found
Content-Disposition: attachement; filename=document.pdf
...

Uploading file with POST :

curl -F "file=@tiger.svg" http://convertit/?to=image/png
HTTP/1.1 302 Found
Content-Disposition: attachement; filename=tiger.png
...

Integration with Django

If your documents do not require login, a simple and stupid template tag can do it :

from django.conf import settings
from django import template
from django.core.urlresolvers import reverse, NoReverseMatch


register = template.Library()


@register.simple_tag
def convert_url(request, sourceurl, *args, **kwargs):
    format = kwargs.pop('format', 'application/pdf')
    try:
        sourceurl = reverse(sourceurl, *args, **kwargs)
    except NoReverseMatch:
        pass
    fullurl = request.build_absolute_uri(sourceurl)
    return "%s?url=%s&to=%s" % (settings.CONVERSION_SERVER,
                                urllib.quote(fullurl),
                                urllib.quote(format))

Which you then use in templates:

<a href="{% convert_url "app:document" object.pk %}">Download PDF version</a>

However, if your view requires authentication, there are several strategies:

  • Auto-login requests coming from ConvertIt server ;
  • Add a login required proxy view that download the file and perform a POST query to ConvertIt ;
  • Setup SSO or any other token mechanism ;
  • Contribute to ConvertIt to add HTTP authentication (url=http://user:pass@host) ;

I made a snippet for the first option

In short...

  • django-appypod is great because templates are WYSIWYG ;
  • ConvertIt is great because it's generic and pluggable ;
  • There are great together because their deliver both office and PDF formats ;

There are alternatives though if PDF is enough for you :

Comments !

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