[Zope] dtml-if and checkboxes

[Jim Penny]

On Fri, Oct 04, 2002 at 04:15:01PM -0400, Hires, Russell (CAP, CARD) wrote:
> Hey All,
> 
> I'm experimenting with zope again, playing with the REQUEST object and form
> objects. In my latest delimma, I've got the following snippet:
> 
> <dtml-if expr="check_box == ('on')">
> The check box is checked!
> </dtml-if>
> 
> What I don't get: if the checkbox is checked in the form, then this works,
> and I get the output. If it isn't checked, then I get an error saying that
> the checkbox ("check_box" in the form) isn't defined. This is borne out as
> well by <dtml-var expr="REQUEST.form">, which shows a text box's name and
> the value that it holds (whether it holds a value or not), and the
> checkbox's name and value ('on'), when it's checked. If it isn't checked, it
> isn't there at all. So, I guess I'm going to have to look to see whether
> it's there or not, right? How would I do that?

This is how HTML works.  Rather bad design.

You want something like:
<dtml-if expr="REQUEST.has_key('check_box') and check_box == 'on'">
  Checked!
</dtml-if>

Note that the second part is completely redundant.

<dtml-if expr="REQUEST.has_key('check_box')">
  Checked!
</dtml-if>

Does the same thing.

In ZPT, this looks like
<span tal:condition="python:request.has_key('check_box')">Checked!</span>

Or, more probably
<input type="checkbox" name="check_box"
       tal:attributes="checked request/check_box|nothing" />


Jim Penny


> 
> Thanks for the help!
> 
> Russell
> 
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