Calculations while looping through dataset

Question

Hi
I've just started using spry which I'm really enjoying. It's
a really great and powerful framework.
I have been able to display a dynamic region and its content
looping through the rows of the dataset.
My problem now is that according to the data in the data set,
I have to make some calculations for each row. I can't seem to find
a way to do it, and don't actually know if it is possible.
this is how my xml looks like:
var xmlStr = "<?xml version=\"1.0\"
encoding=\"iso-8859-1\"?> \
<portfolios> \
<portfolio id=\"12345\"> \
<portfolio_name>Test1</portfolio_name> \
<investment>500000.0000</investment> \
<current_value>513475.7260</current_value> \
</portfolio> \
<portfolio id=\"67890\"> \
<name>Test2</portfolio_name> \
<investment>100000.0000</investment> \
<current_value>103574.6610</current_value> \
</portfolio> \
</portfolios>";
var dsPortfolios = new Spry.Data.XMLDataSet(null,
"/portfolios/portfolio");
var xmlDOMDocument = Spry.Utils.stringToXMLDoc(xmlStr);
dsPortfolios.setDataFromDoc(xmlDOMDocument);
and the display for the data set:
<div spry:region="dsPortfolios"
class="SpryHiddenRegion">
<table>
<tr><th>Name</th><th>Investment</th><th>Current
Value</th><th>Gain</th><th">Pct
Gain</th</tr>
<tr spry:repeat="dsPortfolios">
<td>{name}</td><td>{investment}</td><td>{current_value}</td><td>GAIN_CALC</td><td>GAIN_PE RCENT</td>
</tr>
</table>
</div>
basically, where it says GAIN_CALC and GAIN_PERCENT in the
table, these should be calculation (i.e. GAIN_CALC = current_value
- investment and GAIN_PERCENT = ((current_value -
investment)*100)/investment )
can anybody help me there (if it's possible to do such things
of course)?
Thanks

Answer 1

If you register a post load observer on your data set, you
can perform the calculations on each row and add custom columns
that you can then refer to from your region as data references:
var ds = new Spry.Data.XMLDataSet("portfolios.xml",
"/portfolios/portfolio");
var obs = {};
obs.onPostLoad = function(notifier, data)
var rows = ds.getData();
for (var i = 0; rows && i < rows.length; i++)
var investment = parseFloat(rows[ i ][ "investment" ]);
var currentValue = parseFloat(rows[ i ][ "current_value" ]);
rows[ i ][ "gain_calc" ] = currentValue - investment;
rows[ i ][ "gain_percent" ] = ((currentValue -
investment)*100) / investment;
ds.addObserver(obs);
<div spry:region="dsPortfolios"
class="SpryHiddenRegion">
<table>
<tr><th>Name</th><th>Investment</th><th>Current
Value</th><th>Gain</th><th">Pct
Gain</th</tr>
<tr spry:repeat="dsPortfolios">
<td>{name}</td><td>{investment}</td><td>{current_value}</td><td>{gain_calc}</td><td>{gain_ percent}</td>
</tr>
</table>
</div>
--== Kin ==--