Getting empty form fields with Python cgi stdlib

Question

I am passing multiple form fields which are optional, but which need to be associated with a user. Python\'s cgi.FormDict and cgi.FieldStorage both eliminate blank entries, so i

Answer 1

I'm not sure if you can tweak cgi.FromDict to do what you want, but maybe a solution would be to make every input set uniqe like so:

<input type="text" name="user" />
<input type="text" name="email" />
<input type="text" name="phone" />
<input type="checkbox" value="MailingList1_1" />
<input type="checkbox" value="MailingList2_1" />
<p>
<input type="text" name="user" />
<input type="text" name="email" />
<input type="text" name="phone" />
<input type="checkbox" value="MailingList1_2" />
<input type="checkbox" value="MailingList2_2" />

Note thate MailingList1 and Mailinglist2 now hafe a suffix for the "entry block".

You will have to add this at generation time of you Form and then adapt your processing accordingly by reading the checkboxes like so:

lv_key = 'MailingList1_' + str(i)
MailingList1 = myFormDict[lv_key]
...

Regards,

Martin

Answer 2

Look at the doc below (namely, keep_blank_values parameter):

>>> print cgi.FieldStorage.__init__.__doc__
Constructor.  Read multipart/* until last part.

        Arguments, all optional:

        fp              : file pointer; default: sys.stdin
            (not used when the request method is GET)

        headers         : header dictionary-like object; default:
            taken from environ as per CGI spec

        outerboundary   : terminating multipart boundary
            (for internal use only)

        environ         : environment dictionary; default: os.environ

        keep_blank_values: flag indicating whether blank values in
            percent-encoded forms should be treated as blank strings.
            A true value indicates that blanks should be retained as
            blank strings.  The default false value indicates that
            blank values are to be ignored and treated as if they were
            not included.

        strict_parsing: flag indicating what to do with parsing errors.
            If false (the default), errors are silently ignored.
            If true, errors raise a ValueError exception.

Answer 3

Even if you're using wsgi based frameworks like django or bottle, you're using same <input> names for each field - cgi formdict does not eliminate empty fields, there are no empty fields in the first place. you should give different name attribute for each user.