[Zope] Using batch variables in expressions

[Phillip J. Eby]

At 05:14 PM 10/26/99 -0500, Ben Glazer wrote:
>I want to verify that certain fields in a form have been entered.  Here's a
>code snippet I've tried to use:
>
><dtml-let required="('first', 'last', 'email')">
>	<dtml-in required>
>		   <dtml-var sequence-item> exists
>		</dtml-if>
>	</dtml-in>
></dtml-let>
>
>
>Naturally, I get an error when this is executed, since Python interprets
>"sequence-item" in the dtml-if as subtracting item from sequence.  I thought
><dtml-var sequence-item> might work, but apparently that sort of thing is
>not allowed in an expression.
>
>Is there a way to access the value of sequence-item in an expression?  If
>not, how could I go about verifying that form fields are entered correctly?

Use:

		<dtml-if expr="REQUEST.form[_['sequence-item']]">


>As a side note, is there any good reason that sequence-item isn't spelled
>sequence_item?  Just curious...

There are some reasons, but "good" is a relative question.  One reason is
that it makes it easier for the special mapping object created by the "in"
tag to recognize special variables.

This question is probably becoming a FAQ that should be included in DTML docs.