XForms Essentials

Name

action

Synopsis

This element is a wrapper for other XForms Actions. It contains child elements that are executed in sequence.

action can be used like this:

<action ev:event="DOMActivate">
  <setvalue ref="email/contact" value="email/admin"/>
  <message level="ephemeral">Synchronized email addresses</message>
</action>

Note

One concept that comes into play in more advanced XForms scenarios is what the specification calls "deferred updates.” This feature is intended to reduce the potentially expensive computation that can occur through an XForms Action, as changes to the instance data can trigger a display refresh, a recalculation, a revalidation, or a reconstruction of the dependencies.

Deferred updates occur only through the action container element. It can be thought of as a switch that temporarily turns off the expensive processing, handles the child elements, and then catches up on any processing that still needs to be done. In this way, for instance, a series of insert actions, when placed inside an action element, wouldn’t require a full recalculation for each insert—just one to ensure consistency at the end.

Deferred updates apply to insert, delete, and setvalue.

Warning

Because of the way the XML Events defaulting works, placing ev:event attributes on XForms Action elements inside action will have no effect. Instead, the attribute should be placed on the action element itself—the XForms Actions as child elements will still run within the context of the action.