How to group properly excel data source with rowspan? - excel

Question

From my understanding, <groupExpression> tag will be the one that decides whether a new group will be created or not, if there's a change to the element inside <groupExpression>, a new group will be created.
I want my report to look similar to my Excel data source (refer below) hence I want to group the ID and Name in the Excel file. In my jasperReport.jrxml (refer below), my <groupExpression> for Group1 is the ID column of my Excel File. But when I preview the report (refer below), the ID and Name column is not grouped, instead, there's a null string.
How to properly group them and eliminate the null string?
Excel datasource:
jasperReport.jrxml
<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.2.0.final using JasperReports Library version 6.2.0 -->
<!-- 2016-01-26T15:33:41 -->
<jasperReport xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports http://jasperreports.sourceforge.net/xsd/jasperreport.xsd" name="FirstJasperReport" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="8b8832df-588e-4202-826e-a6b3efcbd22b">
<property name="com.jaspersoft.studio.data.defaultdataadapter" value="ExcelDataBase"/>
<queryString>
<![CDATA[]]>
</queryString>
<field name="ID" class="java.lang.Integer"/>
<field name="Name" class="java.lang.String"/>
<field name="Title" class="java.lang.String"/>
<field name="Balance" class="java.lang.Integer"/>
<variable name="Balance1" class="java.lang.Integer" resetType="Group" resetGroup="Group1" calculation="Count">
<variableExpression><![CDATA[$F{Balance}]]></variableExpression>
</variable>
<variable name="Balance2" class="java.lang.Integer" resetType="Group" resetGroup="Group1" calculation="Sum">
<variableExpression><![CDATA[$F{Balance}]]></variableExpression>
</variable>
<group name="Group1">
<groupExpression><![CDATA[$F{ID}]]></groupExpression>
<groupHeader>
<band height="30">
<rectangle>
<reportElement x="0" y="0" width="400" height="30" backcolor="#DEFCF2" uuid="de6c2f8d-afa6-45b4-b40e-574f2e07057e"/>
</rectangle>
<textField>
<reportElement x="0" y="0" width="100" height="30" uuid="c028645d-9b29-42d3-b91e-d47f15a5b44a"/>
<textFieldExpression><![CDATA[$F{ID}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="100" y="0" width="100" height="30" uuid="85d2844f-ef91-47a1-9223-c6943a25fe4d"/>
<textFieldExpression><![CDATA[$F{Name}]]></textFieldExpression>
</textField>
</band>
</groupHeader>
......
Preview result:
How to make title1 and title2 appear under the group test1, without the null string (similar to the Excel source file)?

Answer 1

The problem is that the excel datasource is passing $F{ID}==null for second record. This generates the null group (as you can see also the name is null).
The easiest way to fix it is to not use rowspan in excel (include all data in the excel sheet).
If this is not possible you need to save the first $F{ID} value and return this if $F{ID}==null
Example
<variable name="First_ID" class="java.lang.Integer" resetType="Group" resetGroup="Group1" calculation="First">
<variableExpression><![CDATA[$F{ID}]]></variableExpression>
</variable>
In group return variable $V{First_ID} if $F{ID}==null
<group name="Group1">
<groupExpression><![CDATA[$F{ID}==null?$V{First_ID}:$F{ID}]]></groupExpression>
... your groupHeader ....
</group>