115 lines
4.5 KiB
Plaintext
115 lines
4.5 KiB
Plaintext
==========================
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Outputting CSV with Django
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==========================
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This document explains how to output CSV (Comma Separated Values) dynamically
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using Django views. To do this, you can either use the `Python CSV library`_ or
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the Django template system.
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.. _Python CSV library: http://docs.python.org/library/csv.html
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Using the Python CSV library
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============================
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Python comes with a CSV library, ``csv``. The key to using it with Django is
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that the ``csv`` module's CSV-creation capability acts on file-like objects, and
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Django's :class:`~django.http.HttpResponse` objects are file-like objects.
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Here's an example::
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import csv
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from django.http import HttpResponse
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def some_view(request):
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# Create the HttpResponse object with the appropriate CSV header.
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response = HttpResponse(mimetype='text/csv')
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response['Content-Disposition'] = 'attachment; filename=somefilename.csv'
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writer = csv.writer(response)
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writer.writerow(['First row', 'Foo', 'Bar', 'Baz'])
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writer.writerow(['Second row', 'A', 'B', 'C', '"Testing"', "Here's a quote"])
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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 MIME type, ``text/csv``. This tells
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browsers that the document is a CSV 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 will 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 CSV 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 CSV-generation API is easy: Just pass ``response`` as the
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first argument to ``csv.writer``. The ``csv.writer`` function expects a
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file-like object, and :class:`~django.http.HttpResponse` objects fit the
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bill.
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* For each row in your CSV file, call ``writer.writerow``, passing it an
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iterable object such as a list or tuple.
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* The CSV module takes care of quoting for you, so you don't have to worry
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about escaping strings with quotes or commas in them. Just pass
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``writerow()`` your raw strings, and it'll do the right thing.
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Using the template system
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=========================
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Alternatively, you can use the :doc:`Django template system </topics/templates>`
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to generate CSV. This is lower-level than using the convenient CSV, but the
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solution is presented here for completeness.
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The idea here is to pass a list of items to your template, and have the
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template output the commas in a :ttag:`for` loop.
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Here's an example, which generates the same CSV file as above::
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from django.http import HttpResponse
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from django.template import loader, Context
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def some_view(request):
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# Create the HttpResponse object with the appropriate CSV header.
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response = HttpResponse(mimetype='text/csv')
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response['Content-Disposition'] = 'attachment; filename=somefilename.csv'
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# The data is hard-coded here, but you could load it from a database or
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# some other source.
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csv_data = (
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('First row', 'Foo', 'Bar', 'Baz'),
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('Second row', 'A', 'B', 'C', '"Testing"', "Here's a quote"),
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)
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t = loader.get_template('my_template_name.txt')
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c = Context({
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'data': csv_data,
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})
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response.write(t.render(c))
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return response
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The only difference between this example and the previous example is that this
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one uses template loading instead of the CSV module. The rest of the code --
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such as the ``mimetype='text/csv'`` -- is the same.
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Then, create the template ``my_template_name.txt``, with this template code:
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.. code-block:: html+django
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{% for row in data %}"{{ row.0|addslashes }}", "{{ row.1|addslashes }}", "{{ row.2|addslashes }}", "{{ row.3|addslashes }}", "{{ row.4|addslashes }}"
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{% endfor %}
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This template is quite basic. It just iterates over the given data and displays
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a line of CSV for each row. It uses the :tfilter:`addslashes` template filter to
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ensure there aren't any problems with quotes.
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Other text-based formats
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========================
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Notice that there isn't very much specific to CSV here -- just the specific
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output format. You can use either of these techniques to output any text-based
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format you can dream of. You can also use a similar technique to generate
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arbitrary binary data; see :doc:`/howto/outputting-pdf` for an example.
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