| ========================== |
| Outputting CSV with Django |
| ========================== |
| |
| This document explains how to output CSV (Comma Separated Values) dynamically |
| using Django views. |
| |
| To do this, you can either use the `Python CSV library`_ or the Django template |
| system. |
| |
| .. _Python CSV library: http://www.python.org/doc/current/lib/module-csv.html |
| |
| Using the Python CSV library |
| ============================ |
| |
| Python comes with a CSV library, ``csv``. The key to using it with Django is |
| that the ``csv`` module's CSV-creation capability acts on file-like objects, |
| and Django's ``HttpResponse`` objects are file-like objects. |
| |
| .. admonition:: Note |
| |
| For more information on ``HttpResponse`` objects, see |
| `Request and response objects`_. |
| |
| For more information on the CSV library, see the `CSV library docs`_. |
| |
| .. _Request and response objects: ../request_response/ |
| .. _CSV library docs: http://www.python.org/doc/current/lib/module-csv.html |
| |
| Here's an example:: |
| |
| import csv |
| from django.http import HttpResponse |
| |
| def some_view(request): |
| # Create the HttpResponse object with the appropriate CSV header. |
| response = HttpResponse(mimetype='text/csv') |
| response['Content-Disposition'] = 'attachment; filename=somefilename.csv' |
| |
| writer = csv.writer(response) |
| writer.writerow(['First row', 'Foo', 'Bar', 'Baz']) |
| writer.writerow(['Second row', 'A', 'B', 'C', '"Testing"', "Here's a quote"]) |
| |
| return response |
| |
| The code and comments should be self-explanatory, but a few things deserve a |
| mention: |
| |
| * The response gets a special mimetype, ``text/csv``. This tells |
| browsers that the document is a CSV file, rather than an HTML file. If |
| you leave this off, browsers will probably interpret the output as HTML, |
| which will result in ugly, scary gobbledygook in the browser window. |
| |
| * The response gets an additional ``Content-Disposition`` header, which |
| contains the name of the CSV file. This filename is arbitrary; call it |
| whatever you want. It'll be used by browsers in the "Save as..." |
| dialogue, etc. |
| |
| * Hooking into the CSV-generation API is easy: Just pass ``response`` as |
| the first argument to ``csv.writer``. The ``csv.writer`` function expects |
| a file-like object, and ``HttpResponse`` objects fit the bill. |
| |
| * For each row in your CSV file, call ``writer.writerow``, passing it an |
| iterable object such as a list or tuple. |
| |
| * The CSV module takes care of quoting for you, so you don't have to worry |
| about escaping strings with quotes or commas in them. Just pass |
| ``writerow()`` your raw strings, and it'll do the right thing. |
| |
| Using the template system |
| ========================= |
| |
| Alternatively, you can use the `Django template system`_ to generate CSV. This |
| is lower-level than using the convenient CSV, but the solution is presented |
| here for completeness. |
| |
| The idea here is to pass a list of items to your template, and have the |
| template output the commas in a ``{% for %}`` loop. |
| |
| Here's an example, which generates the same CSV file as above:: |
| |
| from django.http import HttpResponse |
| from django.template import loader, Context |
| |
| def some_view(request): |
| # Create the HttpResponse object with the appropriate CSV header. |
| response = HttpResponse(mimetype='text/csv') |
| response['Content-Disposition'] = 'attachment; filename=somefilename.csv' |
| |
| # The data is hard-coded here, but you could load it from a database or |
| # some other source. |
| csv_data = ( |
| ('First row', 'Foo', 'Bar', 'Baz'), |
| ('Second row', 'A', 'B', 'C', '"Testing"', "Here's a quote"), |
| ) |
| |
| t = loader.get_template('my_template_name.txt') |
| c = Context({ |
| 'data': csv_data, |
| }) |
| response.write(t.render(c)) |
| return response |
| |
| The only difference between this example and the previous example is that this |
| one uses template loading instead of the CSV module. The rest of the code -- |
| such as the ``mimetype='text/csv'`` -- is the same. |
| |
| Then, create the template ``my_template_name.txt``, with this template code:: |
| |
| {% for row in data %}"{{ row.0|addslashes }}", "{{ row.1|addslashes }}", "{{ row.2|addslashes }}", "{{ row.3|addslashes }}", "{{ row.4|addslashes }}" |
| {% endfor %} |
| |
| This template is quite basic. It just iterates over the given data and displays |
| a line of CSV for each row. It uses the `addslashes template filter`_ to ensure |
| there aren't any problems with quotes. If you can be certain your data doesn't |
| have single or double quotes in it, you can remove the ``addslashes`` filters. |
| |
| .. _Django template system: ../templates/ |
| .. _addslashes template filter: ../templates/#addslashes |