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91 lines
3.3 KiB
Plaintext
91 lines
3.3 KiB
Plaintext
===========================
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Outputting PDFs with Django
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===========================
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This document explains how to output PDF files dynamically using Django views.
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This is made possible by the excellent, open-source ReportLab_ Python PDF
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library.
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The advantage of generating PDF files dynamically is that you can create
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customized PDFs for different purposes -- say, for different users or different
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pieces of content.
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For example, Django was used at kusports.com to generate customized,
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printer-friendly NCAA tournament brackets, as PDF files, for people
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participating in a March Madness contest.
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.. _ReportLab: http://www.reportlab.org/rl_toolkit.html
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Install ReportLab
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=================
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Download and install the ReportLab library from http://www.reportlab.org/downloads.html.
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The `user guide`_ (not coincidentally, a PDF file) explains how to install it.
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Test your installation by importing it in the Python interactive interpreter::
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>>> import reportlab
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If that command doesn't raise any errors, the installation worked.
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.. _user guide: http://www.reportlab.org/rsrc/userguide.pdf
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Write your view
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===============
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The key to generating PDFs dynamically with Django is that the ReportLab API
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acts on file-like objects, and Django's ``HttpResponse`` objects are file-like
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objects.
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.. admonition:: Note
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For more information on ``HttpResponse`` objects, see
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`Request and response objects`_.
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.. _Request and response objects: http://www.djangoproject.com/documentation/request_response/
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Here's a "Hello World" example::
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from reportlab.pdfgen import canvas
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from django.utils.httpwrappers import HttpResponse
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def some_view(request):
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# Create the HttpResponse object with the appropriate PDF headers.
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response = HttpResponse(mimetype='application/pdf')
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response['Content-Disposition'] = 'attachment; filename=somefilename.pdf'
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# Create the PDF object, using the response object as its "file."
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p = canvas.Canvas(response)
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# Draw things on the PDF. Here's where the PDF generation happens.
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# See the ReportLab documentation for the full list of functionality.
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p.drawString(100, 100, "Hello world.")
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# Close the PDF object cleanly, and we're done.
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p.showPage()
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p.save()
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return response
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The code and comments should be self-explanatory, but a few things deserve a
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mention:
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* The response gets a special mimetype, ``application/pdf``. This tells
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browsers that the document is a PDF file, rather than an HTML file. If
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you leave this off, browsers will probably interpret the output as HTML,
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which would result in ugly, scary gobbledygook in the browser window.
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* The response gets an additional ``Content-Disposition`` header, which
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contains the name of the PDF file. This filename is arbitrary: Call it
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whatever you want. It'll be used by browsers in the "Save as..."
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dialogue, etc.
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* Hooking into the ReportLab API is easy: Just pass ``response`` as the
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first argument to ``canvas.Canvas``. The ``Canvas`` class expects a
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file-like object, and ``HttpResponse`` objects fit the bill.
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* Note that all subsequent PDF-generation methods are called on the PDF
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object (in this case, ``p``) -- not on ``response``.
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* Finally, it's important to call ``showPage()`` and ``save()`` on the PDF
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file.
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