Forum: Rails Spinoffs (closed, excessive spam) dynamically change frequency in periodicalUpdater

Hello All,

I've seen this topic but it seems no one has post a response.  I'm
using periodicalUpdater to display live content queried from a
database.  Sometimes the result can be thousands of rows and before it
finishes processing (displaying as a visual indicator) all the data,
the next request is sent to the server. I'd like to have a
periodicalUpdater whose frequency can be set bases on the size of the
result set.  I've tried to set

onSuccess: function() {
this.frequency = dataSize * 5;
}

While this does change this.frequency, but when I tried to

alert(this.frequency) in subsequent onCreate callback, it remains the
value the PU is initialized with. (and the PU updates according to the
initial frequency).

Is there a way to change frequency in the exposed onSuccess or
onCreate call back?  Or how can I pass the dataSize to the
updateComplete in prototype.js, if that's the way to go?

Thanks for your time.
Debbie

Just changing the frequency property wouldn't cause the refresh rate to
change.  It's set up with a setInterval() call which is implemented in 
the
browser.  I'd either monkey patch PeriodicalUpdater to do a 
clearInterval()
followed by setInterval() with the new value, or just shut down the PU 
and
start up a new one.

-Fred

On Fri, Jun 13, 2008 at 12:51 PM, Debbie <liu9471@gmail.com> wrote:

>
> Hello All,
>
> I've seen this topic but it seems no one has post a response.  I'm
> using periodicalUpdater to display live content queried from a
> database.  Sometimes the result can be thousands of rows and before it
> finishes processing (displaying as a visual indicator) all the data,
> the next request is sent to the server. I'd like to have a
> periodicalUpdater whose frequency can be set bases on the size of the
> result set.  I've tried to set


--
Science answers questions; philosophy questions answers.

Thanks Fred.

I've followed the second option and it worked.  Below is my code, in
case someone will find it helpful:

var updateCounter = 0;
function createUpdater(freq)
{
    updater = new Ajax.PeriodicalUpdater("ajaxDIV", "Tickets.jsp", {
        frequency: freq,
        evalScripts: true,
        onCreate: function()
        {
                // change update frequency when data size changes, and
after the initial load
            if (updateCounter != 0 && dataSize != this.frequency / 5)
            {
                alert("data size changed. frequency new: " + dataSize
* 5 + " old: " + this.frequency)
                updateCounter = 0;
                updater = createUpdater(dataSize * 5);
                this.updater.stop();
            }
        },
        onSuccess: function()
        {
            updateCounter ++;
        },
        parameters: Form.serialize($("form"))
    }
            )
            ;
    return updater;
}

Hmm, I'm not quite sure how this works. :)  You appear to be referring 
to
two different updaters (updater and this.updater), but they actually 
refer
to the same object because the function is unbound, and updater is a 
global.

And sadly, I was wrong the whole time, PeriodicalUpdater doesn't use a
setInterval(), but a delayed function call.  You can change the 
frequency
value at any time by calling updater.frequency = newValue.

Sorry for the wild goose chase, but you learned something right? ;-) 
(Like,
don't trust people who post to mailing lists?)

-Fred

On Wed, Jun 25, 2008 at 12:28 PM, Debbie <liu9471@gmail.com> wrote:

>        frequency: freq,
>                updater = createUpdater(dataSize * 5);
>            ;
>    return updater;
> }


--
Science answers questions; philosophy questions answers.