Bug 416703 Mongodb : Display correctly the Number data type
data/org.eclipse.birt.data.oda.mongodb/src/org/eclipse/birt/data/oda/mongodb/impl/MDbResultSet.java
*/
	public String getString( int index ) throws OdaException
	{
        return getString( findFieldName(index) );
	}
	/*
	 * @see org.eclipse.datatools.connectivity.oda.IResultSet#getString(java.lang.String)
	 */
	public String getString( String columnName ) throws OdaException
	{
	    Object columnValue = getFieldValue( columnName );
	    if( columnValue instanceof String )
	        return (String)columnValue;
        if( columnValue instanceof List && ! (columnValue instanceof BasicDBList) )
        {
            
            List<?> fromList = (List<?>)columnValue;
            if( ! fromList.isEmpty() )
            {
                BasicDBList fieldValuesList = new BasicDBList();
                for( int index=0; index < fromList.size(); index++ )
                {
                    fieldValuesList.put( index, fromList.get(index) );
                }
                fieldValuesList.markAsPartialObject();
                return fieldValuesList.toString();  
            }
        }
	    return columnValue != null ? columnValue.toString() : null;
	}