GetAndPostExampleOne

I think this embodies some ideas from GetAndPostToSamePage. I started from the smart form HOWTO. This is condensed to dodge structured text formatting. You can see the real-life version at http://www.sonoma-systems.com/resources/wine.htm .

<dtml-call "REQUEST.set(need_fullname,'')">
<dtml-call "REQUEST.set(need_email,'')">
<dtml-if "REQUEST.REQUEST_METHOD=='POST'">
  <dtml-comment>
  If we're here, the user has hit the submit button and we have
  form data to consider. Validate all fields and either process 
  the form or redisplay it.
  </dtml-comment>
  <dtml-call "REQUEST.set(finished,true)">
  <dtml-unless "fullname">
    <dtml-call "REQUEST.set(finished,false)">
    <dtml-call "REQUEST.set(need_fullname,&lt;b&gt;&lt;--&lt;/b&gt;&lt;i&gt; required&lt;/i&gt;)">
  </dtml-unless>
  <dtml-if "not email">
    <dtml-call "REQUEST.set(finished,false)">
    <dtml-call "REQUEST.set(need_email,&lt;b&gt;&lt;--&lt;/b&gt;&lt;i&gt; required&lt;/i&gt;)">
  <dtml-else>
    <dtml-call "REQUEST.set(e1,_.string.split(email,@))">
    <dtml-call "REQUEST.set(e2,_.string.split(e1[-1],.))">
    <dtml-unless "
                  _.len(e1) == 2 and 
                  _.len(e1[0]) > 0 and 
                  _.len(e2) >= 2 and
                  _.len(e2[0]) > 0 and 
                  _.len(e2[1]) > 0
                 ">
      <dtml-call "REQUEST.set(finished,false)">
      <dtml-call "REQUEST.set(need_email,&lt;b&gt;&lt;--&lt;/b&gt;&lt;i&gt; invalid email address ?&lt;/i&gt;)">
    </dtml-unless>
  </dtml-if>
  <dtml-if "REQUEST.finished == 'true'">
    <dtml-comment>
    we have all the data we need - process the form
    </dtml-comment>  
    <dtml-var form_done>
  <dtml-else>
    <dtml-comment>
    invalid data - redisplay the form
    </dtml-comment>
    <strong>Please address the problems indicated below:</strong>
    <dtml-var form_form>
  </dtml-if>
<dtml-else>
  <dtml-comment>
  no form data - display the form for the first time
  </dtml-comment>
  <dtml-var form_hdr>
  <dtml-var form_form>
</dtml-if>

form_hdr contains introductory content

form_form contains the actual form, something like this:

<form id="exampleform" action="exampleform" method="post">
<label for="fullname"><b>Full Name:</b></label>
<input type="text" id="fullname" name="fullname" value="&dtml.missing-fullname;" size="30" maxlength="60" tabindex=1>
<font color="red"><dtml-var need_fullname></font>
<br>
<label for="email"><b>Email:</b></label>
<input type="text" id="email" name="email" value="&dtml.missing-email;" size="30" maxlength="60" tabindex=2> 
<font color="red"><dtml-var need_email></font>
<br>
...

and form_done does the action and displays acknowledgement content. When managing a zope object you would redisplay the form along with the acknowledgement.