How to deal with XML Schema choice elements in XForms

Hi,

 I am new to OPS and XForms, currently I have what feels like a massive learning curve. One sticking point that I have is how to represent an XML schema choice in XForms. If somebody could point me in the right direction I would be very gratefull.

An axample of what I mean can be seen in the following schema fragment:

...
<complexType>
   <choice>
      <element name="argument">
         <complexType>
            <sequence>
               <element name="name" type="string"></element>
               <element name="type" type="task:input-type"></element>
               <element name="tag" type="string" nillable="true"></element>
               <element name="position" type="short"></element>
               <element name="value" type="task:value"></element>
             </sequence>
         </complexType>
      </element>
      <element name="param">
         <complexType>
            <sequence>
               <element name="name" type="string"></element>
               <element name="value" type="task:value"></element>
            </sequence>
         </complexType>
      </element>
   </choice>
</complexType>
...

Regards,

Neal Johnston-Ward



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Indeed, that raises some issues, such as what your
instance will look like.  It might be that you need
to have two instances, one for each choice, and depending
on a computed value or user selection, inputs become
"relevant" or not.

How would you or the user determine which choice
to present?

--Hank


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Sent: Thursday, June 08, 2006 1:48 PM
Subject: [ops-users] How to deal with XML Schema choice elements in XForms


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Neal,

 > One sticking point that I have is how to represent an XML schema
 > choice in XForms. If somebody could point me in the right direction
 > I would be very gratefull.

So your instance could look like:

<foo>
   <bar/>
   <argument>
     <!-- etc. -->
   </argument>
</foo>

or:

<foo>
   <bar/>
   <param>
     <!-- etc. -->
   </param>
</foo>

If you already *have* such an XForms isntance, then handling the
choice in the XForms controls is very easy:

<xforms:group ref="argument">
     <!-- Controls for the content of the argument element -->
</xforms:group>
<xforms:group ref="param">
     <!-- Controls for the content of the argument element -->
</xforms:group>

If one of the groups points to a non-existing node, then that group
simply won't display as it is considered non-relevant.

Now if you want to *create* such an instance, it is again not that
difficult. Create two files containing prototypes for the data you
want to create:

argument-template.xml:

<argument>
   <!-- etc. -->
</argument>

param-template.xml:

<param>
   <!-- etc. -->
</param>

Then refer to these files in your XForms model:

<xforms:instance id="argument-template-instance"
src="argument-template.xml"/>
<xforms:instance id="param-template-instance" src="param-template.xml"/>

Then at the time you want to actually insert either <argument> or
<param> elements in your instance, execute the following actions:

<xforms:insert nodeset="bar" at="1" position="after"
                origin="instance('argument-template-instance')"/>

or:

<xforms:insert nodeset="bar" at="1" position="after"
                origin="instance('param-template-instance')"/>

Now exactly when you perform such insertion is up to you: you may have
"Add Argument" and "Add Param" buttons (xforms:trigger), for example.

I hope this helps.

-Erik

 > An axample of what I mean can be seen in the following schema fragment:
 >
 > ...
 > <complexType>
 >    <choice>
 >       <element name="argument">
 >          <complexType>
 >             <sequence>
 >                <element name="name" type="string"></element>
 >                <element name="type" type="task:input-type"></element>
 >                <element name="tag" type="string"
nillable="true"></element>
 >                <element name="position" type="short"></element>
 >                <element name="value" type="task:value"></element>
 >              </sequence>
 >          </complexType>
 >       </element>
 >       <element name="param">
 >          <complexType>
 >             <sequence>
 >                <element name="name" type="string"></element>
 >                <element name="value" type="task:value"></element>
 >             </sequence>
 >          </complexType>
 >       </element>
 >    </choice>
 > </complexType>
 > ...
 >
 > Regards,
 >
 > Neal Johnston-Ward

--
Orbeon - XForms Everywhere:
http://www.orbeon.com/blog/



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