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Fixed #21179 -- Added a StreamingHttpResponse example for CSV files.

Thanks charettes for the suggestion.
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1 parent 5840445 commit fad47367bf622635b4cf931db72310cce41cebb4 @zedr zedr committed with timgraham Mar 4, 2014
Showing with 41 additions and 1 deletion.
  1. +40 −0 docs/howto/outputting-csv.txt
  2. +1 −1 docs/ref/request-response.txt
40 docs/howto/outputting-csv.txt
@@ -75,6 +75,46 @@ For more information, see the Python documentation of the :mod:`csv` module.
.. _`csv module's examples section`:
.. _`python-unicodecsv module`:
+.. _streaming-csv-files:
+Streaming large CSV files
+When dealing with views that generate very large responses, you might want to
+consider using Django's :class:`~django.http.StreamingHttpResponse` instead.
+For example, by streaming a file that takes a long time to generate you can
+avoid a load balancer dropping a connection that might have otherwise timed out
+while the server was generating the response.
+In this example, we make full use of Python generators to efficiently handle
+the assembly and transmission of a large CSV file::
+ import csv
+ from django.utils.six.moves import range
+ from django.http import StreamingHttpResponse
+ class Echo(object):
+ """An object that implements just the write method of the file-like
+ interface.
+ """
+ def write(self, value):
+ """Write the value by returning it, instead of storing in a buffer."""
+ return value
+ def some_streaming_csv_view(request):
+ """A view that streams a large CSV file."""
+ # Generate a sequence of rows. The range is based on the maximum number of
+ # rows that can be handled by a single sheet in most spreadsheet
+ # applications.
+ rows = (["Row {0}".format(idx), str(idx)] for idx in range(65536))
+ pseudo_buffer = Echo()
+ writer = csv.writer(pseudo_buffer)
+ response = StreamingHttpResponse((writer.writerow(row) for row in rows),
+ content_type="text/csv")
+ response['Content-Disposition'] = 'attachment; filename="somefilename.csv"'
+ return response
Using the template system
2 docs/ref/request-response.txt
@@ -909,7 +909,7 @@ StreamingHttpResponse objects
The :class:`StreamingHttpResponse` class is used to stream a response from
Django to the browser. You might want to do this if generating the response
takes too long or uses too much memory. For instance, it's useful for
-generating large CSV files.
+:ref:`generating large CSV files <streaming-csv-files>`.
.. admonition:: Performance considerations

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