From inside a post processor, there is only one way to discover the dimensions and levels that the user initially selected (most likely in an MDX query): you introspect the location evaluated by the post processor.
Here is a small post processor example (it is designed to run in the ActivePivot Sandbox application). The post processor defines a contextual dimension, the time dimension in this example. If the user has expanded the time dimension, then the evaluated location will have a depth of at least 2 (depth 1 means only the AllMember is selected for that dimension). Then you can decide to return a different measure or calculation based on that knowledge.
/*
* (C) Quartet FS 2010
* ALL RIGHTS RESERVED. This material is the CONFIDENTIAL and PROPRIETARY
* property of Quartet Financial Systems Limited. Any unauthorized use,
* reproduction or transfer of this material is strictly prohibited
*/
package com.quartetfs.pivot.sandbox.postprocessor.impl;
import java.util.Properties;
import com.quartetfs.biz.pivot.IActivePivot;
import com.quartetfs.biz.pivot.ILocation;
import com.quartetfs.biz.pivot.impl.Util;
import com.quartetfs.biz.pivot.postprocessing.impl.ABasicPostProcessor;
import com.quartetfs.fwk.QuartetException;
import com.quartetfs.fwk.QuartetExtendedPluginValue;
/**
*
* @author Quartet FS
*
*/
@QuartetExtendedPluginValue(
interfaceName = "com.quartetfs.biz.pivot.postprocessing.IPostProcessor",
key = ContextualPostProcessor.PLUGIN_TYPE
)
public class ContextualPostProcessor extends ABasicPostProcessor<Double> {
/** serialVersionUID */
private static final long serialVersionUID = 4484708084267009957L;
/** Plugin key */
static final String PLUGIN_TYPE = "CTX";
/** Ordinal of the time dimension */
protected int timeDimensionOrdinal = -1;
/** Constructor */
public ContextualPostProcessor(String name, IActivePivot pivot) {
super(name, pivot);
}
@Override
public String getType() { return PLUGIN_TYPE; }
@Override
public void init(Properties properties) throws QuartetException {
super.init(properties);
// Store the ordinal of the time dimension
timeDimensionOrdinal = Util.findDimension(pivot.getDimensions(), "TimeBucket");
}
@Override
protected Double doEvaluation(ILocation location, Object[] underlyingMeasures) throws QuartetException {
if(location.getLevelDepth(timeDimensionOrdinal - 1) > 1) {
return (Double) underlyingMeasures[0];
} else {
return (Double) underlyingMeasures[1];
}
}
}
Here is how you can declare the post processor in the cube description:
<measure name="ctx" isIntrospectionMeasure="false">
<!-- This post processor dynamically buckets an underlying measure -->
<!-- It works together with a dynamic bucket dimension. -->
<postProcessor pluginKey="CTX">
<properties>
<entry key="id" value="SUM" />
<entry key="underlyingMeasures" value="pv.SUM,pnl.SUM" />
</properties>
</postProcessor>
</measure>