XLWT example

import xlwt

XL_DATE_STYLE = xlwt.easyxf(num_format_str='DD.MM.YYYY')
XL_DATETIME_STYLE = xlwt.easyxf(num_format_str='DD.MM.YYYY HH:MM:SS')


def return_xls():
    stream = StringIO()

    wb = xlwt.Workbook(encoding='utf8')
    ws = wb.add_sheet('Sheet 1')
    row_n = col_n = 0

    ws.set_panes_frozen(True)  # frozen headings instead of split panes
    ws.set_horz_split_pos(row_n + 1)  # in general, freeze after last heading row
    ws.set_remove_splits(True)  # if user does unfreeze, don't leave a split there

    FIELDS = ('col1', 'col2', 'col3', 'col4')

    for field in FIELDS:
        ws.write(row_n, col_n, field)
        col_n += 1

    number_fields = ('col2',)
    date_fields = ('col3',)

    db = MembershipDB()

    row_n += 1
    for row in db.get_members():
        col_n = 0
        for field in FIELDS:
            if field == 'password':
                continue
            if field in date_fields:
                typ = 'datetime'
            elif field in number_fields:
                typ = 'number'
            else:
                typ = ''
            value = row[field]
            if typ == 'datetime':
                if value:
                    if isinstance(value, basestring):
                        value = DateTime(value, datefmt="en")
                    if value.time == 0.0:
                        format = XL_DATE_STYLE
                    else:
                        format = XL_DATETIME_STYLE
                    ws.write(row_n, col_n, value, format)
            else:
                ws.write(row_n, col_n, value)
            col_n += 1
        row_n += 1

    wb.save(stream)
    return stream.getvalue()