Re: [Xsltforms-support] refreshing the screen while performing a submission - why does this not wor
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Re: [Xsltforms-support] refreshing the screen while performing a submission - why does this not work?
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From: C. M. Sperberg-M. <cm...@bl...> - 2016-07-05 19:24:37
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On Jun 28, 2016, at 1:37 PM, Alain Couthures wrote:
> 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 the suggestion. I have now finally had the opportunity
to try it. For the record, this form of the submission did not work:
<xf:submission id="send-query" resource="./balbus.php" method="get" replace="instance" instance="results">
<xf:delete ev:event="xforms-submit" nodeset="instance('results')/child::node()"/>
<xf:insert ev:event="xforms-submit-serialize" context="instance('results')" origin="instance('ui')/query-in-progress"/>
</xf:submission>
(The use of different events on the delete and insert was an attempt
to force them to happen in a particular order. Using xforms-submit-serialize
on both didn't work, either.)
But when the submission takes this form, I got the desired behavior (the old results
vanish and the text 'Query in progress' appears instead):
<xf:submission id="send-query" resource="./balbus.php" method="get" replace="instance" instance="results">
<xf:setnode ev:event="xforms-submit-serialize" ref="instance('results')" inner="serialize(instance('ui')/query-in-progress)"/>
</xf:submission>
I do not understand why setnode should work when insert + delete
does not (and if anyone reading this understands why, I'll be glad of
an explanation), but for the moment I'm happy, and I record this
outcome for the sake of anyone who finds this thread while trying to
solve a similar problem.
Michael
>
> 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.
>>
>
>
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--
****************************************************************
* C. M. Sperberg-McQueen, Black Mesa Technologies LLC
* http://www.blackmesatech.com
* http://cmsmcq.com/mib
* http://balisage.net
****************************************************************
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