Question

I am working with Python’s SimpleCookie and I ran into this problem and I am not sure if it is something with my syntax or what. Also, this is classwork for my Python class so it is meant to teach about Python so this is far from the way I would do this in the real world.

Anyway, so basically I am keeping information input into a form in a cookie. I am attempting to append to the previous cookie with the new information entered. But for some reason on the third entry of data the cookie suddenly gets ‘\’ in it. I am not sure where they are coming from though.

This is the type of output I am getting:

‘\’\\’\\\\’test:more\\\\’:rttre\\’:more\’:and more’

#!/usr/local/bin/python  import cgi,os,time,Cookie #error checking import cgitb cgitb.enable()  if 'HTTP_COOKIE' in os.environ:     cookies = os.environ['HTTP_COOKIE']     cookies = cookies.split('; ')     for myCookie in cookies:         myCookie = myCookie.split('=')         name = myCookie[0]         value = myCookie[1]         if name == 'critter' :             hideMe = value  #import critterClass  #get info from form form = cgi.FieldStorage() critterName = form.getvalue('input') input2 = form.getvalue('input2') hiddenCookie = form.getvalue('hiddenCookie') hiddenVar = form.getvalue('hiddenVar')  #make cookie cookie = Cookie.SimpleCookie()  #set critter Cookie if critterName is not None:     cookie['critter'] = critterName #If already named else:     #if action asked, append cookie     if input2 is not None:         cookie['critter'] = hideMe+':'+input2     else:         cookie['critter'] = 'default'  print cookie   print 'Content-type: text/html\n\n'    if ((critterName is None) and (input2 is None)):     print '''     <form name='critter' id='critter' method='post' action='critter.py'>     <label for='name'>Name your pet: <input type='text' name='input' id='input' /></label>     <input type='submit' name='submit' id='submit' value='Submit' />     </form>     ''' else:     formTwo ='''     <form name='critter2' id='critter2' method='post' action='critter.py'>     <label for='name'>%s wants to: <input type='text' name='input2' id='input2' /></label>     <input type='hidden' name='hiddenVar' id='hiddenVar' value='%s' />     <input type='submit' name='submit' id='submit' value='Submit' />     </form>     [name,play,feed,mood,levels,end]     '''     print formTwo % (critterName,critterName)  if 'HTTP_COOKIE' in os.environ:     cookies = os.environ['HTTP_COOKIE']     cookies = cookies.split('; ')     for myCookie in cookies:         myCookie = myCookie.split('=')         name = myCookie[0]         value = myCookie[1]         if name == 'critter' :             print 'name'+name             print 'value'+value 

Answer 1

As explained by others, the backslashes are escaping double quote characters you insert into the cookie value. The (hidden) mechanism in action here is the SimpleCookie class. The BaseCookie.output() method returns a string representation suitable to be sent as HTTP headers. It will insert escape characters (backslashes) before double quote characters and before backslash characters.

The

print cookie 

statement activates BaseCookie.output().

On each trip your string makes through the cookie’s output() method, backslashes are multiplied (starting with the 1st pair of quotes).

>>> c1=Cookie.SimpleCookie() >>> c1['name']='A:0' >>> print c1 Set-Cookie: name='A:0' >>> c1['name']=r''A:0'' >>> print c1 Set-Cookie: name='\'A:0\'' >>> c1['name']=r''\'A:0\''' >>> print c1 Set-Cookie: name='\'\\\'A:0\\\'\'' >>>