This document explains how to output PDF files dynamically using Django views. This is made possible by the excellent, open-source ReportLab Python PDF library.
The advantage of generating PDF files dynamically is that you can create customized PDFs for different purposes – say, for different users or different pieces of content.
For example, Django was used at kusports.com to generate customized, printer-friendly NCAA tournament brackets, as PDF files, for people participating in a March Madness contest.
$ python -m pip install reportlab
Test your installation by importing it in the Python interactive interpreter:
>>> import reportlab
If that command doesn’t raise any errors, the installation worked.
The key to generating PDFs dynamically with Django is that the ReportLab API acts on file-like objects, and Django’s FileResponse objects accept file-like objects.
Here’s a “Hello World” example:
import io from django.http import FileResponse from reportlab.pdfgen import canvas def some_view(request): # Create a file-like buffer to receive PDF data. buffer = io.BytesIO() # Create the PDF object, using the buffer as its "file." p = canvas.Canvas(buffer) # Draw things on the PDF. Here's where the PDF generation happens. # See the ReportLab documentation for the full list of functionality. p.drawString(100, 100, "Hello world.") # Close the PDF object cleanly, and we're done. p.showPage() p.save() # FileResponse sets the Content-Disposition header so that browsers # present the option to save the file. buffer.seek(0) return FileResponse(buffer, as_attachment=True, filename='hello.pdf')
The code and comments should be self-explanatory, but a few things deserve a mention:
as_attachment=Trueis passed to
FileResponse, it sets the appropriate
Content-Dispositionheader and that tells Web browsers to pop-up a dialog box prompting/confirming how to handle the document even if a default is set on the machine. If the
as_attachmentparameter is omitted, browsers will handle the PDF using whatever program/plugin they’ve been configured to use for PDFs.
filenameparameter. It’ll be used by browsers in the “Save as…” dialog.
canvas.Canvascan be fed to the FileResponse class.
p) – not on
save()on the PDF file.
ReportLab is not thread-safe. Some of our users have reported odd issues with building PDF-generating Django views that are accessed by many people at the same time.
Notice that there isn’t a lot in these examples that’s PDF-specific – just the bits using
reportlab. You can use a similar technique to generate any arbitrary format that you can find a Python library for. Also see Outputting CSV with Django for another example and some techniques you can use when generated text-based formats.
Django Packages provides a comparison of packages that help generate PDF files from Django.