s=str(binary)

[gert]

How do you convert s back to binary data in python 3 so I can put in a
sqlite blob ?
Is there a build in function or do I need to use binascii ?
byte(s) or bin(s) would make more sense but can not figure it out ?

 

[John Machin]

How do you convert s back to binary data in python 3 so I can put in a
sqlite blob ?
Is there a build in function or do I need to use binascii ?
byte(s) or bin(s) would make more sense but can not figure it out ?

Can't imagine why you would do str(binary_data) especially if you want
it back again ... however:

According to the fabulous manual:

str([object[, encoding[, errors]]])
Return a string version of an object, using one of the following
modes:
[snip]
When only object is given, this returns its nicely printable
representation. For strings, this is the string itself. The difference
with repr(object) is that str(object) does not always attempt to
return a string that is acceptable to eval(); its goal is to return a
printable string.

Hmm looks like (1) we need to do the dreaded eval() and (2) there's no
guarantee it will work.
.... blob = bytes()
.... if eval(str(blob)) != blob:
.... print(i, blob, str(blob), eval(str(blob)))
....
Looks like it's going to work, but you better be rather sure that you
trust the source.

HTH,
John

 

[gert]

Can't imagine why you would do str(binary_data) especially if you want
it back again ... however:

def application(environ, response):
s = str(environ['wsgi.input'].read())
b = compile('boundary=(.*)').search(environ['CONTENT_TYPE']).group
(1)
p = compile(r'.*Content-Type: application/octet-stream\\r\\n\\r\\n
(.*)\\r\\n--'+b+'.*'+b+'--', DOTALL).match(s).group(1)
db.execute('UPDATE users SET picture=? WHERE uid=?',
(p,session.UID))

According to the fabulous manual:

str([object[, encoding[, errors]]])
Return a string version of an object, using one of the following
modes:
[snip]
When only object is given, this returns its nicely printable
representation. For strings, this is the string itself. The difference
with repr(object) is that str(object) does not always attempt to
return a string that is acceptable to eval(); its goal is to return a
printable string.

Hmm looks like (1) we need to do the dreaded eval() and (2) there's no
guarantee it will work.

...    blob = bytes()
...    if eval(str(blob)) != blob:
...       print(i, blob, str(blob), eval(str(blob)))
...

Looks like it's going to work, but you better be rather sure that you
trust the source.

Any other suggestions ?

 

[John Machin]

Can't imagine why you would do str(binary_data) especially if you want
it back again ... however:

def application(environ, response):
    s = str(environ['wsgi.input'].read())
    b = compile('boundary=(.*)').search(environ['CONTENT_TYPE']).group
(1)
    p = compile(r'.*Content-Type: application/octet-stream\\r\\n\\r\\n
(.*)\\r\\n--'+b+'.*'+b+'--', DOTALL).match(s).group(1)
    db.execute('UPDATE users SET picture=? WHERE uid=?',
(p,session.UID))
[snip]

Looks like it's [it being eval(str(blob))] going to work, but you better be rather sure that you
trust the source.

Any other suggestions ?

Yeah.

(a) don't write obfuscatory code :-0

E.g.
(1) re.compile(pattern).search(data) -> re.search(pattern, data)
(2) re.compile(pattern).match(data) -> re.match(pattern, data)
(3) re.match('.*blahblah', data) -> re.search('blahblah', data)

(b) don't use re when ordinary str or bytes methods will do

E.g. instead of:
b = re.search('boundary=(.*)'), environ['CONTENT_TYPE']).group(1)
try
b = environ['CONTENT_TYPE'].split('boundary=')[1]

(c) Is that code meant to be rough pseudocode to illustrate what you
are trying to do, or is it meant to be working code? If the latter:
* Do you have this working in 2.X?
* Are you sure the pattern to retrieve the picture is correct?
* What is the "Content-Transfer-Encoding"?

(d) Surely there must be a library somewhere that parses that kind of
data for you ...

(e) if all else fails, I'd suggest:

instead of s = str(binary)
do s = binary.decode('latin1')
# this won't change the number of characters and will allow
# reconstitution of your non-ascii bytes
Then do your DIY parsing
then at the end do
blob = p.encode('latin1')
# blob will be type bytes which is presumably what the database
expects

HTH,
John

 

[gert]

def application(environ, response):
    s = str(environ['wsgi.input'].read())
    b = compile('boundary=(.*)').search(environ['CONTENT_TYPE']).group
(1)
    p = compile(r'.*Content-Type: application/octet-stream\\r\\n\\r\\n
(.*)\\r\\n--'+b+'.*'+b+'--', DOTALL).match(s).group(1)
    db.execute('UPDATE users SET picture=? WHERE uid=?',
(p,session.UID))

(a) don't write obfuscatory code :-0

E.g.
(1) re.compile(pattern).search(data) -> re.search(pattern, data)
(2) re.compile(pattern).match(data) -> re.match(pattern, data)
(3) re.match('.*blahblah', data) -> re.search('blahblah', data)

(b) don't use re when ordinary str or bytes methods will do

E.g. instead of:
b = re.search('boundary=(.*)'), environ['CONTENT_TYPE']).group(1)
try
b = environ['CONTENT_TYPE'].split('boundary=')[1]

(c) Is that code meant to be rough pseudocode to illustrate what you
are trying to do, or is it meant to be working code? If the latter:
* Do you have this working in 2.X?
yep

* Are you sure the pattern to retrieve the picture is correct?

yep http://91.121.53.159/file.txt

* What is the "Content-Transfer-Encoding"?

print (environ['Content-Transfer-Encoding'],file=sys.stderr)
Key error flash 10 does not send it ?

(d) Surely there must be a library somewhere that parses that kind of
data for you ...

p = FieldStorage(fp=environ['wsgi.input'], environ=environ)
In python 3 you get TypeError: Can't convert 'bytes' object to str
implicitly

(e) if all else fails, I'd suggest:

instead of s = str(binary)
do s = binary.decode('latin1')
# this won't change the number of characters and will allow
# reconstitution of your non-ascii bytes
Then do your DIY parsing
then at the end do
blob = p.encode('latin1')
# blob will be type bytes which is presumably what the database
expects

Victory
http://91.121.53.159/appwsgi/www/register/register.htm
http://code.google.com/p/appwsgi/source/browse/trunk

from db import Db
from session import Session
from re import search,match,DOTALL

def application(environ, response):
db = Db()
cookie = "SID="+environ['QUERY_STRING']
session = Session(db,cookie,'guest')
response('200 OK', [('Content-type', 'text/xml'), ('Set-Cookie',
session.COOKIE)])
if not session.GID : return []
s = environ['wsgi.input'].read().decode('latin1')
b = search(r'boundary=(.*)',environ['CONTENT_TYPE']).group(1)
p = search(r'Content-Type: application/octet-stream\r\n\r\n(.*)\r
\n--',s,DOTALL).group(1)
db.execute('UPDATE users SET picture=? WHERE uid=?',(p.encode
('latin1'),session.UID))
xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
xml+= "<root>"+str(db.ERROR)+"</root>"
response('200 OK', [('Content-type', 'text/xml')])
return [xml]

 

[gert]

b = environ['CONTENT_TYPE'].split('boundary=')[1]
oops forgot, is indeed better solution