download_as_csv_view.py

"""
    csv exporter
    ~~~~~

    Usage:
    * in your admin class for model, insert: actions = [ download_as_csv_view ]
    * add columns names in HEADER
    * add data columns in _make_csv_row

    :copyright: (c) https://github.com/danie1k
    :license: GNU General Public License
"""

def download_as_csv_view(modeladmin, request, queryset):
    """A view that streams a large CSV file."""
    MAX_PER_PAGE = 65536
    FILENAME = ''
    HEADER = [] # Document header row with columns names

    import csv, tempfile, StringIO, zipfile
    from django.http import HttpResponse
    from django.core.paginator import Paginator

    def _make_csv_row(row):
        return [] # Columns with data in row

    paginator = Paginator(queryset, MAX_PER_PAGE)

    if paginator.num_pages == 1:
        response = HttpResponse(content_type='text/csv')
        response['Content-Disposition'] = ('attachment; '
                                          'filename="{}.csv"'.format(FILENAME))

        writer = csv.writer(response, delimiter=';', dialect='excel')
        writer.writerow(HEADER)

        for row in queryset:
            writer.writerow(_make_csv_row(row))

        return response

    response = HttpResponse(content_type='application/x-zip-compressed')
    response['Content-Disposition'] = ('attachment; '
                                       'filename="{}.zip"'.format(FILENAME))

    # This is where my zip will be written
    buff = StringIO.StringIO()
    # This is my zip file
    zip_archive = zipfile.ZipFile(buff, mode='w')

    for page in paginator.page_range:
        temp_file = StringIO.StringIO()

        writer = csv.writer(temp_file, delimiter=';', dialect='excel')
        writer.writerow(HEADER)

        rows = paginator.page(page)
        for row in rows:
            writer.writerow(_make_csv_row(row)) 

        zip_archive.writestr('{}.part{}.csv'.format(FILENAME, page),
                             temp_file.getvalue())

    zip_archive.close()

    response.write(buff.getvalue())
    return response

download_as_csv_view.short_description = "Download as CSV"