Downloading a csv file in django

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I am trying to download a CSV file using HttpResponse to make sure that the browser treats it as an attachment. I follow the instructions provided here but my browser does not prompt a "Save As" dialog. I cannot figure out what is wrong with my function. All help is appreciated.

  dev savefile(request):
        try:
            myfile = request.GET['filename']
            filepath = settings.MEDIA_ROOT + 'results/'
            destpath = os.path.join(filepath, myfile)
            response = HttpResponse(FileWrapper(file(destpath)), mimetype='text/csv' ) 
            response['Content-Disposition'] = 'attachment; filename="%s"' %(myfile)
            return response
        except Exception, err:
            errmsg = "%s"%(err)
            return HttpResponse(errmsg)

Happy Pat's day!

Best Answer

If the file is static (i.e not generated specifically for this request) you shouldn't be serving it through django anyway. You should configure some path (like /static/) to be served by your webserver, and save all the django overhead.

If the file is dynamic, there are 2 options:

  1. Create it in memory and serve it from django.
  2. Create it on the disk, and return a HttpResponseRedirect to it, so that your webserver deals with the download itself (if the file is very large, you should use this option).

As for serving it dynamically, I've been using the following code (which is a simplified version of ExcelResponse)

import StringIO
from django.db.models.query import ValuesQuerySet, QuerySet

class CSVResponse(HttpResponse):

  def __init__(self, data, output_name='data', headers=None, encoding='utf8'):

    # Make sure we've got the right type of data to work with
    valid_data = False
    if isinstance(data, ValuesQuerySet):
        data = list(data)
    elif isinstance(data, QuerySet):
        data = list(data.values())
    if hasattr(data, '__getitem__'):
        if isinstance(data[0], dict):
            if headers is None:
                headers = data[0].keys()
            data = [[row[col] for col in headers] for row in data]
            data.insert(0, headers)
        if hasattr(data[0], '__getitem__'):
            valid_data = True
    assert valid_data is True, "CSVResponse requires a sequence of sequences"

    output = StringIO.StringIO()
    for row in data:
        out_row = []
        for value in row:
            if not isinstance(value, basestring):
                value = unicode(value)
            value = value.encode(encoding)
            out_row.append(value.replace('"', '""'))
        output.write('"%s"\n' %
                     '","'.join(out_row))            
    mimetype = 'text/csv'
    file_ext = 'csv'
    output.seek(0)
    super(CSVResponse, self).__init__(content=output.getvalue(),
                                        mimetype=mimetype)
    self['Content-Disposition'] = 'attachment;filename="%s.%s"' % \
        (output_name.replace('"', '\"'), file_ext)

To use it, just use return CSVResponse(...) passing in a list of lists, a list of dicts (with same keys), a QuerySet, a ValuesQuerySet

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