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 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.
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:
Python’s csv module does not support Unicode input. Since Django uses Unicode internally this means strings read from sources such as HttpRequest are potentially problematic. There are a few options for handling this:
For more information, see the Python documentation of the csv module.
Alternatively, you can use the Django template system to generate CSV. This is lower-level than using the convenient Python csv module, 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.
Notice that there isn’t very much specific to CSV here – just the specific output format. You can use either of these techniques to output any text-based format you can dream of. You can also use a similar technique to generate arbitrary binary data; see Outputting PDFs with Django for an example.
Dec 23, 2012