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
...\> py -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
objects accept file-like objects.
Here’s a “Hello World” example:
from django.http import FileResponse
from reportlab.pdfgen import canvas
# 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.
# FileResponse sets the Content-Disposition header so that browsers
# present the option to save the file.
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=True is passed to
FileResponse, it sets the
Content-Disposition header 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_attachment parameter is omitted,
browsers will handle the PDF using whatever program/plugin they’ve been
configured to use for PDFs.
filename parameter. It’ll be used by browsers
in the “Save as…” dialog.
canvas.Canvas can be fed to the
p) – not on
save() on the PDF
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
reportlab. You can use a similar technique to generate any
arbitrary format that you can find a Python library for. Also see
How to create CSV output 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.