Thursday, August 27, 2009

APEX and Google Visualizations: Create sub-zero dashboards

APEX is cool, Google is cool, Google Visualizations are even cooler. So the combination the coolest technologies available is sub-zero!
A Google Visualization needs can get it's data programmatically by using javascript: create a DataTable object and use addColumn to define the columns and addRows to define the rows. But a Visualization can also be fed with a JSON object. So I created a package prodcure that reads a sql query and spits out a JSON string in the format Google likes. This procedure is called by an APEX On Demand Application Process.
In every APEX page the necessary Google Visualization packages are loaded by calling google.load with some packages, like this:

google.load('visualization', '1', {packages :[ 'geomap', 'intensitymap', 'map' ]});
(The google.load function is loaded in the template by referencing a javascript file http://www.google.com/jsapi).
Every chart is defined as an HTML Region. The source of that Region contains a SQL Statement embedded in a DIV.

<div id="geomap">select 'US-'||cust_state state, sum(order_total) OrderTotal
from demo_customers c, demo_orders o
where o.customer_id = c.customer_id
group by cust_state</div>
In the Region Footer the JSON string is pulled using a getData function. That function calls the PL/SQL JSON-generator procedure that fetches the SQL query from the APEX Repository. Subsequently two simple calls are enough to replacing the SQL query with the Google chart.

<script type="text/javascript">
$s('geomap',null)
var data = getData('#REGION_ID#');
var geomap = new google.visualization.GeoMap($x('geomap'));
var options = {};
options['region'] = 'US';
options['width'] = '300px';
options['height'] = '300px';
geomap.draw(data, options);
</script>
On the Google Visualization website the expected data (number of columns and type) are described for every type of chart. By just entering a SQL Statement that corresponds with the Google specs, I can produce any Google Visualization within seconds (once the SQL is correct ;-) )!
You can experience the APEX-Google Visualization live on apex.oracle.com.

Why would you use Google Visualizations (apart from "just because we can")? If your needs are fulfilled using the standard APEX / AnyChart stuff, there is no need. But there are some charts, especially the animated, time related, charts that are sooo cool and AnyCharts doesn't contain all the charts Google does (and vice versa). And I guess the number of Google Visualizations will grow, as everyone can add gadgets to that library.
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