Problem with action on event:xforms-change

Hallo,

I have a problem with xf:action. I make my own control, and I have an instance:

<xf:model>
    <xf:instance id="src"><value/></xf:instance>
</xf:model>

This instance is created to hold name of control from main instance, which is observer of my action:

<xf:action ev:event="xforms-value-changed" ev:observer="xxf:instance('fr-form-instance')/*/*[name() = saxon:evaluate(instance('src'))]">
    <xf:send ev:event="DOMActivate" submission=".." />
</xf:action>

Unfortunately it doesn't work. There is no effect after change input which is associated with instance('src'). What I'm doing wrong?

regards, Tom

Event observers are static, not dynamic, so you cannot use an XPath expressions as an observer.

What you can do is observe *around* all your controls, and then filter with a condition. Something like:

<xf:action
  ev:event="xforms-value-changed"
  ev:observer="my-group-around-controls"
  if="some condition here but I am not sure which condition is yours">
    <xf:send submission="id of your submission"/>
</xf:action>

-Erik

Thanks for response!

I think, that condition is something like:
xxf:instance('fr-form-instance')/*/*[name() = saxon:evaluate(instance('src'))] isChanged

but how can I write this in xforms

Hi Tom,

What you were trying to do in your first example in this thread looked like listening on a "value changed" event on a node in an instance. But XForms doesn't work this way: xforms-value-changed comes from the control whose value has changed, not the node in the instance.

In instance('src') you have the name of the element in the instance, e.g. first-name, because the element is <first-name/>. Is the form created with Form Builder? If it is, then the id of the control will be first-name-control, i.e. the name with the -control postfix. So you should be able to do the test with something like:

    if="event('xxf:targetid') = concat(instance('src'), '-control')"

While looking for a solution, you might want first to put not if="...", and have an <xf:message> to see if the event handler is called, at all, and then when it is, make it show the value of event('xxf:targetid') and instance('src') to check they are what you expect.

Alex

Thank You! I'm going to try this solution

regards