Bug 146548 [regression]Data type convert in chart data binding doesn't work.
Description: Data type convert in chart data binding doesn't work. Steps to reproduce: 1. New sample data source and dataset from OFFICES. 2. Insert a chart, bind it to dataset 3. Edit data binding to change officecode from string type to integer type 4. Drag officecode to y-series Expected result: No errors. Actual result: Unable to use a text data to render a numerical/datetime axis. org.eclipse.birt.chart.exception.ChartException at: org.eclipse.birt.chart.factory.Generator.build(Generator.java:985) org.eclipse.birt.chart.ui.swt.wizard.internal.ChartPreviewPainter.updateBuffer(ChartPreviewPainter.java:152) org.eclipse.birt.chart.ui.swt.wizard.internal.ChartPreviewPainter.renderModel(ChartPreviewPainter.java:333) org.eclipse.birt.chart.ui.swt.wizard.TaskSelectData.doLivePreview(TaskSelectData.java:1043) org.eclipse.birt.chart.ui.swt.wizard.TaskSelectData.changeTask(TaskSelectData.java:984) org.eclipse.birt.chart.ui.swt.wizard.ChartAdapter.notifyChanged(ChartAdapter.java:68) org.eclipse.emf.common.notify.impl.BasicNotifierImpl.eNotify
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/expression/ExprEvaluateUtil.java
return exprValue;
	}
	
	/**
	 * @param expr
	 * @param odiResult
	 * @param scope
	 * @return
	 * @throws DataException
	 */
	public static Object evaluateCompiledExpression( CompiledExpression expr,
			IResultIterator odiResult, Scriptable scope ) throws DataException
	{
		
		
		if ( expr instanceof ColumnReferenceExpression )
		{
			
			ColumnReferenceExpression colref = (ColumnReferenceExpression) expr;
			if ( colref.isIndexed( ) )
			{
				int idx = colref.getColumnindex( );
				
				if ( idx == 0 )
					return new Integer( odiResult.getCurrentResultIndex( ) );
				else if ( odiResult.getCurrentResult( ) != null )
					return odiResult.getCurrentResult( )
							.getFieldValue( idx );
				else
					return null;