jasper reports - Subreport variable always return null

Question

I need to put a variable in the master report which value came from a subreport. I followed instructions from the web, but I've always got null. For testing, I put "18" in the expression of subreport variable, but returns null.

Can someone help me? I will put the JRXML below.

I created a variable var1 in master report:

1. Name: var1
2. Calculation: System
3. Reset type: Report
4. Increment type: None

In the subreport, I created the variable returnValue

1. Calculation: No Calculation Function
2. Expression: 18
3. Increment type: None
4. Reset type: Report

In the master, I configured the return value:

1. From Variable: returnValue
2. To Variable: var1
3. Calculation Type: Nothing

Following the two xml files

---

MASTER

<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.6.0.final using JasperReports Library version 4.0.2  -->
<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="master" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
    <property name="com.jaspersoft.studio.data.defaultdataadapter" value="One Empty Record"/>
    <variable name="var1" class="java.lang.Integer" calculation="System"/>
    <title>
        <band height="79" splitType="Stretch">
            <staticText>
                <reportElement x="153" y="26" width="100" height="30"/>
                <text><![CDATA[MASTER]]></text>
            </staticText>
        </band>
    </title>
    <summary>
        <band height="246" splitType="Stretch">
            <subreport>
                <reportElement x="80" y="10" width="360" height="50"/>
                <connectionExpression><![CDATA[$P{REPORT_CONNECTION}]]></connectionExpression>
                <returnValue subreportVariable="returnValue" toVariable="var1"/>
                <subreportExpression><![CDATA["sub1.jasper"]]></subreportExpression>
            </subreport>
            <textField>
                <reportElement x="149" y="147" width="100" height="30"/>
                <textFieldExpression><![CDATA[$V{var1}]]></textFieldExpression>
            </textField>
        </band>
    </summary>
</jasperReport>

---

SUBREPORT

<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.6.0.final using JasperReports Library version 4.0.2  -->
<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="sub1" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
    <variable name="returnValue" class="java.lang.Integer">
        <variableExpression><![CDATA[18]]></variableExpression>
    </variable>
    <title>
        <band height="79" splitType="Stretch">
            <staticText>
                <reportElement x="212" y="24" width="100" height="30"/>
                <text><![CDATA[SUB 1]]></text>
            </staticText>
        </band>
    </title>
</jasperReport>

Answer 1

1. One problem is that the sub report is never getting executed since its main dataset does not return any row. So change the When No Data Type of sub report from <NULL> to All Sections No Detail -

2. Secondly the variable returnValue in Sub report have Reset type as None -

3. Finally the variable var1 rendered using TextField should have Evaluation Time as Report -

Below are updated JRXMLs -

MASTER

<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.15.0.final using JasperReports Library version 6.15.0-dd49bfb94918336b8321d5507193f0169ead4e95  -->
<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="master" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="d1a326d7-0db4-41f6-9791-6c0abc454731">
    <property name="com.jaspersoft.studio.data.defaultdataadapter" value="One Empty Record"/>
    <variable name="var1" class="java.lang.Integer" calculation="System"/>
    <title>
        <band height="79" splitType="Stretch">
            <staticText>
                <reportElement x="153" y="26" width="100" height="30" uuid="ccc1c45e-e056-4a8e-8adc-cebefd388bc9"/>
                <text><![CDATA[MASTER]]></text>
            </staticText>
        </band>
    </title>
    <summary>
        <band height="246" splitType="Stretch">
            <subreport>
                <reportElement x="80" y="10" width="360" height="50" uuid="e251bfe7-5e81-4b79-9bc6-5f0e6c1d9555"/>
                <connectionExpression><![CDATA[$P{REPORT_CONNECTION}]]></connectionExpression>
                <returnValue subreportVariable="returnValue" toVariable="var1"/>
                <subreportExpression><![CDATA["sub.jasper"]]></subreportExpression>
            </subreport>
            <textField evaluationTime="Report">
                <reportElement x="149" y="147" width="100" height="30" uuid="24c3289e-f7a5-4137-9254-1fa2605f6741"/>
                <textFieldExpression><![CDATA[$V{var1}]]></textFieldExpression>
            </textField>
        </band>
    </summary>
</jasperReport>

SUBREPORT

<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.15.0.final using JasperReports Library version 6.15.0-dd49bfb94918336b8321d5507193f0169ead4e95  -->
<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="sub1" pageWidth="595" pageHeight="842" whenNoDataType="AllSectionsNoDetail" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="97bfa906-b658-45f6-aff8-3bfa505251b3">
    <variable name="returnValue" class="java.lang.Integer" resetType="None">
        <variableExpression><![CDATA[18]]></variableExpression>
    </variable>
    <title>
        <band height="79" splitType="Stretch">
            <staticText>
                <reportElement x="212" y="24" width="100" height="30" uuid="9332a235-2823-4b53-b6f8-0a7c56d58aee"/>
                <text><![CDATA[SUB 1]]></text>
            </staticText>
        </band>
    </title>
</jasperReport>