"""Encode multipart form data to upload files via POST."""
from __future__ import print_function
import mimetypes
import random
import string
_BOUNDARY_CHARS = string.digits + string.ascii_letters
def encode_multipart(fields, files, boundary=None):
r"""Encode dict of form fields and dict of files as multipart/form-data.
Return tuple of (body_string, headers_dict). Each value in files is a dict
with required keys 'filename' and 'content', and optional 'mimetype' (if
not specified, tries to guess mime type or uses 'application/octet-stream').
>>> body, headers = encode_multipart({'FIELD': 'VALUE'},
... {'FILE': {'filename': 'F.TXT', 'content': 'CONTENT'}},
... boundary='BOUNDARY')
>>> print('\n'.join(repr(l) for l in body.split('\r\n')))
'--BOUNDARY'
'Content-Disposition: form-data; name="FIELD"'
''
'VALUE'
'--BOUNDARY'
'Content-Disposition: form-data; name="FILE"; filename="F.TXT"'
'Content-Type: text/plain'
''
'CONTENT'
'--BOUNDARY--'
''
>>> print(sorted(headers.items()))
[('Content-Length', '193'), ('Content-Type', 'multipart/form-data; boundary=BOUNDARY')]
>>> len(body)
193
"""
def escape_quote(s):
return s.replace('"', '\\"')
if boundary is None:
boundary = ''.join(random.choice(_BOUNDARY_CHARS) for i in range(30))
lines = []
for name, value in fields.items():
lines.extend((
'--{0}'.format(boundary),
'Content-Disposition: form-data; name="{0}"'.format(escape_quote(name)),
'',
str(value),
))
for name, value in files.items():
filename = value['filename']
if 'mimetype' in value:
mimetype = value['mimetype']
else:
mimetype = mimetypes.guess_type(filename)[0] or 'application/octet-stream'
lines.extend((
'--{0}'.format(boundary),
'Content-Disposition: form-data; name="{0}"; filename="{1}"'.format(
escape_quote(name), escape_quote(filename)),
'Content-Type: {0}'.format(mimetype),
'',
value['content'],
))
lines.extend((
'--{0}--'.format(boundary),
'',
))
body = '\r\n'.join(lines)
headers = {
'Content-Type': 'multipart/form-data; boundary={0}'.format(boundary),
'Content-Length': str(len(body)),
}
return (body, headers)
if __name__ == '__main__':
import doctest
doctest.testmod()
