Aggregate instances when performing submission

> Hi,
>
> If you have an XForms model containing two (or more) data instances, what is
> the recommended way to then perform an XML submission which requires bits of
> data from both instances?
>
> For example,
>
> <xf:instance id="alpha">
>   <alpha>
>       Some data...
>   </alpha>
> </xf:instance>
>
> <xf:instance id="beta">
>   <beta>
>       Some more data...
>   </beta>
> </xf:instance>
>
> <xf:instance id="result">
>   <result>
>       Some data...
>   </result>
> </xf:instance>
>
> As far as I am aware the submission mechanism only allows you to reference
> data from a single instance e.g.
>
> <xf:submission id="do-alpha" method="post" resource="alpha"
> ref="instance('alpha')" replace="instance" instance="resullt"/>
>
>
> Therefore when you need to process data from two separate instances I
> believe it is necessary to copy data from one instance to the other thus
> duplicating data. This is really awkward and gets messy very quickly.
>
> Is there an easier way to do this? For example is there a way to aggregate
> the data from multiple instances when you submit? For example something
> like:
>
> <xf:submission id="do-alpha-beta" method="post" resource="alpha-beta"
> ref="aggregate('data', instance('alpha'), instance('beta'))"
> replace="instance" instance="resullt"/>
>
> This approach doesn't work at the moment, but would seem to be a nice way of
> creating the required instance data on-the-fly.
>
> One other alternative I could think of would be to aggregate the data
> sources when the page is constructed, but this is just pushing the problem
> to the XPL rather than the XForm code.
>
>
> Any thoughts on this would be much appreciated.
>
> Regards,
> Neil
>
>
>
>
> --
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>
>
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>

> Hi Erik,
>
> Thanks for this suggestion. This seems to be along the right lines, but
> unfortunately the xxforms:element() function throws an exception when passed
> more than two arguments e.g.
>
> 2011-10-26 09:51:58,970 ERROR XFormsServer  - xforms-submit-error - setting
> throwable {throwable: "org.orbeon.saxon.trans.XPathException: XPath syntax
> error at char 39 in {...lement('result', $form, $data}:
>    Cannot find a matching 3-argument function named
> {http://orbeon.org/oxf/xml/xforms}element()
>        at
> org.orbeon.saxon.expr.ExpressionParser.grumble(ExpressionParser.java:149)
>        at
> org.orbeon.saxon.expr.ExpressionParser.parseFunctionCall(ExpressionParser.java:1852)
>
> It is tantalisingly close to being a solution though, as when you just pass
> in two arguments it does behave as you would expect e.g. passes an instance
> to the pipeline comprising a root element name and a child element.
>
> Am I missing a technique to make the xxforms:element function accept a third
> argument to create a composite element? Or is this a feature that you think
> could be added to Orbeon Forms relatively easily?
>
>
>
> Regards,
> Neil
>
>
>
>
>
> --
> View this message in context: http://orbeon-forms-ops-users.24843.n4.nabble.com/Aggregate-instances-when-performing-submission-tp3936413p3939913.html
> Sent from the Orbeon Forms (ops-users) mailing list archive at Nabble.com.
>
>
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>
>