invoke action after completion of page load

[the_cthulhu]

hi there!
I'm having some problems with the following scenario:
There's a backing bean that generates the data that should be displayed in some DataGrid. As this computation takes some time and blocks the page from beeing loaded I tried to display some ...loading... info and after completion of the message replace it with the datatable.
At the moment i'm doing this using the following code:

<a4j:poll
id="userRecommendationPoll" interval="1"
action="#{userRecBox.evaluate}"
enabled="#{userRecBox.resultCount==0}"
reRender="userRecommendationResult" />

The evaluate action computes the data for the DataGrid with id userRecommendationResult. The method doesn't return the data but some boolean without purpose to complete the ajax-request-cyclw.
Is there a better way to do this, as using a4j:poll tends to be problematic if there are no results after completion. Optimal solution would be something like

<a4j:invoke action="#{userRecBox.evaluate}" reRender="userRecommendationResult" />

that rerenders the DataGrid after result of evaluate is returned.
Regards,
Florian

[daniel.soneira]

You could try a combination of jQuery (onReady) calling an a4j:jsFunction that triggers the loading of the data - with an aj4:status onstart showing some "loading" div - hiding it in onstop again.

So your page would show up - when the DOM is built (rich:jQuery timing="onload") you invoke your data loading function (a4j:jsFunction) as an AJAX request - while that function is working in the background you display some status information (a4j:status onstart / onstop)

[the_cthulhu]

that sounds like a more elegant approach without the possbility of being DDOSed by the users because of the poll not beeing disabled.
I tried the following:

<rich:jQuery timing="onload" query="eval()"></rich:jQuery>
 <h:form>
 <a4j:jsFunction name="eval" action="#{userRecBox.evaluate()}" reRender="userRecommendationResult">
 </a4j:jsFunction>
 </h:form>

this leads to the strange error:

An Error Occurred:
Property 'evaluate' not found on type de.nightcrawler.session.box.userRecommendation.UserRecBox_$$_javassist_3

My first thought was that the action is not called properly but some property. I created a delegate Method "getEvaluate()" in userRecBox but this changes nothing.
Some idea?

[the_cthulhu]

problem solved!
sorry, I tinkered with the old poll code and jsut commented it out, but it was still parsed I think ;)

[the_cthulhu]

very strange behviour ;)
So, the above code works perfectly, but only für the jsFunction eval. This overrides the javascript eval function that is called in the generated jQuery:

jQuery(document).ready(function() {
var selector = 'page';
 try {
selector = eval("");
 } catch (e) {}
jQuery(selector).eval();

So the actual method invocation is done in line 4 and not in the last line.
Any clues how to solve this problem?

[daniel.soneira]

Naming a JS function "eval" is somewhat dangerous, as it is already a function standard Javascript function.

I would go for another name [I'll use "youreval" in the example below]

The problem here is that you didn't use a jQuery API function name (like "each", "toggle", ...) in the "query" argument.

Try something like this:

<rich:jQuery selector="document" timing="onload" query="each(function () {youreval();})"/>

This will invoke the inline callback function for every element that matches your selector (which should be your document - so only invoked once).

[the_cthulhu]

Great, Thank you!
I wasn't accustomed to jQuery so I didn't have this great idea.
Works fine, thank you very much!