diff --git a/docs/howto/outputting-csv.txt b/docs/howto/outputting-csv.txt index 1f9efb5a4b..8e7c311757 100644 --- a/docs/howto/outputting-csv.txt +++ b/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`: http://docs.python.org/library/csv.html#examples .. _`python-unicodecsv module`: https://github.com/jdunck/python-unicodecsv +.. _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 ========================= diff --git a/docs/ref/request-response.txt b/docs/ref/request-response.txt index 8212511f7e..f4a8a17ed1 100644 --- a/docs/ref/request-response.txt +++ b/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 `. .. admonition:: Performance considerations