[Zope] How to use "lower" attribute (or function) to catch duplicate User IDs?

[Bob King]

I am new to Zope (less than a week) and I'm in the process of writing a 
small portal where users can sign themselves up.

Right now it is working, but I have a few known problems - one of which is 
that my routine that checks for duplicate User IDs is case-sensitive (i.e. 
it would allow "bob","Bob" and "BOB" all to register).

I also realize that what I have right now is kluged together - I'm sure 
there is a more efficient (and more elegant) way of doing what I've done.

Here's the basic outline of what I have done so far.  It is very skeletal 
right now, as I'm figuring out how to use Zope.

Public Access page:
-> Contains link to sign up
-> Contains link to members only side

Private Page:
-> contains link to make entry in member database
-> contains link to list members

Logic Flow:

NewLAGUserForm - captures first attempt to create User ID & calls 
VerifyLAGUserForm

VerifyLAGUserForm - checks data, if all OK, calls AddLAGUser, otherwise 
redisplays entry form (with appropriate error messages) and submits input 
to VerifyLAGUserForm again

AddLAGUser - makes entry into acl_users with appropriate role, makes entry 
into SQL database with user information, emails "thank you" message to user 
with User ID & password info

SECURITY QUESTION: - In order for this to work I had to set the security 
for on acl_users (for this folder) to "Manage users" for "Anonymous".  Does 
this open up any way for someone to gain access directly to the acl_users 
folder?  I've tried to and it seems like it is still safe - I have the 
'Member' role hardcoded into the add user script.

Code Examples

Rather than post lengthy codes segments to the list, I put all of the code 
examples online as text files via the following link:

http://examples.subbob.net  (non-zope)

The working implementation of the above files may be found at:

http://www.subbob.net:8081/wargames

Feel free to try it out as I'm only in testing right now and will be 
purging the database when testing is complete.

Outstanding Questions:

1) How to track a "state" within a given DTML Document or Method?  The 
Verify form is very cumbersome as I go through each "test" twice.

The first set of nested ifs are used to determine the overall validity of 
the submission - if it gets to the "center" of the nest, the data is submitted.

If any errors exist, then I retest each parameter prior to redisplaying the 
form in order to flag the associated input box with an error message.  I 
had to do that way because I couldn't figure out a way to accomplish it 
like this in DTML:

If email-good then
     email-error=0
else
     email-error=1

Then check, if all error values=0, submit the form, otherwise display the 
errors.

I'll appreciate any feedback on what I've done so far - I've probably 
violated most accepted practices of "good" zope coding! :)