[Tutor] elementtree, lists, and dictionaries

[Kent Johnson]

If you iterate over the author nodes you can check the user name and password of each in turn.

Not tested code!

def authenticateAuthor(author, password):
     authorxml = 'author.xml'
     path = os.path.join(xml, authorxml)
     if not os.path.exists(path):
         return False, False
     else:
         tree = E.ElementTree(file=path)
         for authorNode in tree.getiterator('author'):
             user = authorNode.find('user').text
             pass = authorNode.find('password').text

             if author == user:
                 if password == pass:
                     return True, True
                 else:
                     return False, True

         return False, True


Luis N wrote:
> Hi,
> 
> This code works, but I don't like it much:
> 
> def authenticateAuthor(author, password):
>     authorxml = 'author.xml'
>     path = os.path.join(xml, authorxml)
>     try: if not os.path.exists(path):
>         authorfile = False
>     else:
>         authorfile = True
>         tree = E.ElementTree(file=path)
>         u = tree.getiterator('user')
>         p = tree.getiterator('password')

Here you could say
   d = dict( (unode.text, pnode.text) for unode, pnode in zip(u, p))

>         ul = []
>         pl = []
>         for unode in u:
>             ul.append(unode.text)
>         for pnode in p:
>             pl.append(pnode.text)
>         d = {}
>         for i in range(len(ul)):
>             d[ul[i]] = pl[i]

>         if d.has_key(author):
>             if d.get(author) == password:
>                 auth = True
>             else:
>                 auth = False

or
   try:
     if d[author] == password:
       auth = True
   except KeyError:
     auth = False

or, if you are sure password will not be None, just skip the has_key():
   if d.get(author) == password:
     ...

(I hate using has_key() followed by a get()...
>             return auth, authorfile
> 
> It assumes a great deal, such as that there is no chance that there
> will be more users then there are passwords, etc. given an xml
> document format such as:
> 
> <root>
>     <author>
>         <user>authorname</user>
>         <password>authorpassword</password>
>     </author>
> </root>
> 
> I don't like how I'm making two lists and then turning them into a
> dictionary. It seems unpythonic.
> 
> Suggestions are appreciated.
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