This document explains how to output PDF files dynamically using Django views.\nThis is made possible by the excellent, open-source ReportLab Python PDF\nlibrary.
\nThe advantage of generating PDF files dynamically is that you can create\ncustomized PDFs for different purposes – say, for different users or different\npieces of content.
\nFor example, Django was used at kusports.com to generate customized,\nprinter-friendly NCAA tournament brackets, as PDF files, for people\nparticipating in a March Madness contest.
\nThe ReportLab library is available on PyPI. A user guide (not\ncoincidentally, a PDF file) is also available for download.\nYou can install ReportLab with pip:
$ pip install reportlab\nTest your installation by importing it in the Python interactive interpreter:
\n>>> import reportlab\nIf that command doesn’t raise any errors, the installation worked.
\nThe key to generating PDFs dynamically with Django is that the ReportLab API\nacts on file-like objects, and Django’s HttpResponse\nobjects are file-like objects.
Here’s a “Hello World” example:
\nfrom reportlab.pdfgen import canvas\nfrom django.http import HttpResponse\n\ndef some_view(request):\n # Create the HttpResponse object with the appropriate PDF headers.\n response = HttpResponse(content_type='application/pdf')\n response['Content-Disposition'] = 'attachment; filename="somefilename.pdf"'\n\n # Create the PDF object, using the response object as its "file."\n p = canvas.Canvas(response)\n\n # Draw things on the PDF. Here's where the PDF generation happens.\n # See the ReportLab documentation for the full list of functionality.\n p.drawString(100, 100, "Hello world.")\n\n # Close the PDF object cleanly, and we're done.\n p.showPage()\n p.save()\n return response\nThe code and comments should be self-explanatory, but a few things deserve a\nmention:
\nThe response gets a special MIME type, application/pdf. This\ntells browsers that the document is a PDF file, rather than an HTML file.\nIf you leave this off, browsers will probably interpret the output as\nHTML, which would result in ugly, scary gobbledygook in the browser\nwindow.
The response gets an additional Content-Disposition header, which\ncontains the name of the PDF file. This filename is arbitrary: Call it\nwhatever you want. It’ll be used by browsers in the “Save as…” dialog, etc.
The Content-Disposition header starts with 'attachment; ' in this\nexample. This forces Web browsers to pop-up a dialog box\nprompting/confirming how to handle the document even if a default is set\non the machine. If you leave off 'attachment;', browsers will handle\nthe PDF using whatever program/plugin they’ve been configured to use for\nPDFs. Here’s what that code would look like:
response['Content-Disposition'] = 'filename="somefilename.pdf"'\nHooking into the ReportLab API is easy: Just pass response as the\nfirst argument to canvas.Canvas. The Canvas class expects a\nfile-like object, and HttpResponse objects fit the\nbill.
Note that all subsequent PDF-generation methods are called on the PDF\nobject (in this case, p) – not on response.
Finally, it’s important to call showPage() and save() on the PDF\nfile.
If you’re creating a complex PDF document with ReportLab, consider using the\nio library as a temporary holding place for your PDF file. This\nlibrary provides a file-like object interface that is particularly efficient.\nHere’s the above “Hello World” example rewritten to use io:
from io import BytesIO\nfrom reportlab.pdfgen import canvas\nfrom django.http import HttpResponse\n\ndef some_view(request):\n # Create the HttpResponse object with the appropriate PDF headers.\n response = HttpResponse(content_type='application/pdf')\n response['Content-Disposition'] = 'attachment; filename="somefilename.pdf"'\n\n buffer = BytesIO()\n\n # Create the PDF object, using the BytesIO object as its "file."\n p = canvas.Canvas(buffer)\n\n # Draw things on the PDF. Here's where the PDF generation happens.\n # See the ReportLab documentation for the full list of functionality.\n p.drawString(100, 100, "Hello world.")\n\n # Close the PDF object cleanly.\n p.showPage()\n p.save()\n\n # Get the value of the BytesIO buffer and write it to the response.\n pdf = buffer.getvalue()\n buffer.close()\n response.write(pdf)\n return response\nNotice that there isn’t a lot in these examples that’s PDF-specific – just the\nbits using reportlab. You can use a similar technique to generate any\narbitrary format that you can find a Python library for. Also see\nOutputting CSV with Django for another example and some techniques you can use\nwhen generated text-based formats.