Re: [Xsltforms-support] refreshing the screen while performing a submission - why does this not work?

[Alain C. <ala...@ag...>]

As a possible workaround, you might try to insert the text, before the 
submission being effectively sent, at the event "xforms-submit-serialize".

Thank you for your feedback!

--Alain

Le 20/06/2016 à 20:32, C. M. Sperberg-McQueen a écrit :
> I have a form that performs a query against a database back end,
> shows the results, and keeps the search box open so the user can
> issue a new search.
>
>    http://tlrr.blackmesatech.com/2016/01/balbus.xhtml
>
> (Useful searches: "Alfenus", "Balbus" for fast searches, "Cicero" for a
> slower one.)
>
> In the current version of the form, nothing visual happens when
> the user issues a new search; if the search is slow, the user can think
> "something went wrong, the browser didn't notice the click, I'll
> click again".  So I'd like the Search button to clear the old results,
> display the text "Query in progress ..." in some way (ideally in the
> work area where the results used to be), and issue the query submission
> to the back end.
>
> A first cut made the trigger look like this:
>
>        <xf:trigger>
> 	<xf:label>Search</xf:label>
> 	<xf:action ev:event="DOMActivate">
> 	  <xf:delete nodeset="instance('results')/child::node()"/>
> 	  <xf:insert context="instance('results')" origin="instance('ui')/query-in-progress"/>
> 	  <xf:setvalue ref="instance('q')/startpos" value="1"/>
> 	  <xf:send submission="send-query"/>
> 	</xf:action>
>        </xf:trigger>
>
> And I added the 'Query in progress ...' display this way:
>
>      <xf:group ref="instance('results')/query-in-progress">
>        <p>Query in progress ...</p>
>      </xf:group>
>
> (It should be noted that the send-query submission replaces the
> 'results' instance entirely, so the empty 'query-in-progress' element
> there goes away when the results of the query are returned.)
>
> The trigger and group just shown, however, do not in fact make
> the old results disappear or the text "Query in progress ..." appear;
> there no change to the display until the results of the query come back.
>
> Consulting the spec, I see that my problem is apparently described
> in the section on 'deferred updates', near the beginning of section 10:
>
>> Deferred Updates: Sequences of one or more XForms Actions have a deferred effect on XForms model and user interface processing. Implementations are free to use any strategy to accomplish deferred updates, but the end result must be as follows: Instance data changes performed by a set of actions do not result in immediate computation dependency rebuilding, recalculation, revalidate and form control refreshing until the termination of the outermost action handler, as described here.
> OK, I think I can see the point of that rule.
>
> Later on in the same section, however, it says
>
>> Actions that directly invoke rebuild, recalculate, revalidate, or refresh always have an immediate effect, and clear the corresponding deferred update flag. The XForms Actions in this category are:
>>
>> rebuild
>> recalculate
>> revalidate
>> refresh
> So I tried inserting first one, then a different one, and finally all four of these actions
> into my trigger:
>
>        <xf:trigger>
> 	<xf:label>Search</xf:label>
> 	<xf:action ev:event="DOMActivate">
> 	  <!--* <xf:message level="ephemeral">Query in progress</xf:message> *-->
> 	  <xf:delete nodeset="instance('results')/child::node()"/>
> 	  <xf:insert context="instance('results')" origin="instance('ui')/query-in-progress"/>
>
> 	  <xf:rebuild/>
> 	  <xf:recalculate/>
> 	  <xf:revalidate/>
> 	  <xf:refresh/>
>
> 	  <xf:setvalue ref="instance('q')/startpos" value="1"/>
> 	  <xf:send submission="send-query"/>
> 	</xf:action>
>        </xf:trigger>
>
> The result is that the behavior is still unchanged.  Have I misunderstood the spec?
> Am I doing something wrong?
>
> How can I cause a single button press to (a) clear the results and display a 'be patient'
> message, and (b) perform a submission which will automatically clear that be-patient
> message when the results come back?
>
> Thanks for any help.
>