Bug 124629 Use Top/Bottom n in a field containing null value inside will cause DataException.
Description: Use Top/Bottom n in a field containing null value inside will cause DataException. Steps to reproduce: 1. New a data source and dataset 2. Add a filter on a field, set operator to top 5 3. Click Preview Result. Result: A BIRT exception occurred. Plug-in Provider:Eclipse.org Plug-in Name:BIRT Data Engine Plug-in ID:org.eclipse.birt.data Version:2.0.0 Error Code:data.engine.DataConversionError Error Message:An error happened in data type conversion. Can not convert the value of {NULL_VALUE_!@#$%^&} to Double type.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/script/NEvaluator.java
package org.eclipse.birt.data.engine.script;
import org.eclipse.birt.core.data.DataTypeUtil;
import org.eclipse.birt.core.exception.BirtException;
import org.eclipse.birt.data.engine.api.IConditionalExpression;
import org.eclipse.birt.data.engine.api.IScriptExpression;
import org.eclipse.birt.data.engine.core.DataException;
import org.eclipse.birt.data.engine.i18n.ResourceConstants;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.Scriptable;
/**
 * The implementation of this class is used to evaluate TopN/BottomN expressions 
 * @author lzhu
 *
 */
public abstract class NEvaluator