Dealing with optional attributes

Hi,

I have an instance:

<xf:instance id="resource">
  <resource>
    <contributor ident=""/>
  </resource>
</xf:instance>

where the ident attribute is optional according to the schema. However,
if it takes a value then there is a pattern it must match so I add a bind:

<xf:bind nodeset="instance('resource')/contributor/@ident"
constraint="matches(., pattern)"/>

The control is then just:

<xf:input ref="instance('resource')/contributor/@ident"/>

Now if the user does not specify a value then the ident attribute takes
on the empty value which is illegal according to the schema since it
does not match the pattern so: <contributor ident=""/> is illegal but
<contributor /> is fine. But if I remove the ident attribute from the
instance then the control does not appear.

Is there any way of having a loose binding so that if a value is
specified, it has to agree with the constraint but if one is not
specified then the attribute is not submitted. There is nothing that it
can be made relevant on.

    Cheers,
     
    Matthew



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Is it possible to use an <xf:trigger>, and not an <xf:submit>,
so that you can take an <xf:action> to <xf:setvalue> the
relevant attribute of your instance when (just before) it
is submitted?

And your submission would need to use the relevant="true",
the default, to prune the element out.

Just a guess,
Hank
UCSB

----- Original Message -----
From: "Matthew Graham" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, April 17, 2007 2:42 PM
Subject: [ops-users] Dealing with optional attributes


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Matthew,

There is no concept of "lazy" binding of a control to a yet-to-exist
attribute in XForms.

For that kind of use case, you probably need to have a trigger (which
can display as a nice "+" icon) that allows inserting the attribute with
xforms:insert when it is missing. Once the attribute is visible, your
xforms:select1 will show and allow selecting a valid value of the attribute.

To remove the attribute, you can use a trigger as well ("-") that
removes the attribute with xforms:delete, or you can decide to
automatically remove the attribute when the user select a special value
in the xforms:select1.

This would be a nice little example to have ;-)

-Erik

Matthew Graham wrote:
--
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http://www.orbeon.com/



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Hi Mathew,
    Please find as attachment a sample test case I created from my understanding. Hope the attached sample is self explanatory and serves your requirement. Try it in the xforms-sandbox.

Thanks
Joseph Lawrence
Stabilix Solutions

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