Posted by ncrofts on
URL: https://discuss.orbeon.com/Aggregate-instances-when-performing-submission-tp3936413.html

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