How to avoid using a lots of ternary operators for translation of value to text - jasper-reports

Question

I am using JasperReports to create some reports of a Django web application.
Let's say that I have a model that has an id and a value. This value is a Django choice so I end up in my database with only the keys and not the values (the values are in my code). To make it more clear for people that don't use Django, I end up with something like that in my database:
id value
1 'GD'
2 'VG'
3 'VG'
4 'VG'
5 'GD'
6 'AV'
7 'GD'
8 'AV'
I want to display Good instead of 'GD', Average instead of 'AV' and Very Good instead of VG in my report. I know that this can be done with two equally not desirable to me options:
Create a new table in my database that has key - value and join that in the JR query. I really hate this because I'd need to create around 10 such tables.
Use the ternary operator to display the correct value:
field.equals("GD")?"Good":(field.equals("AV")?"Average":(field.equals("VG")?"Very good":"-"))
I also hate this because it would be very complicated if I had, for instance, 10 key-value pairs.
My ideal solution would be to define a dictionary (HashMap) variable in my report that would contain all the key value pairs and then just do a DICTIONARY.get(field) to represent the field value. Can this be done ? Can you possibly propose another, better solution?
Please don't tell me to alter my database design, I know that some people won't like but it perfect for my needs.

Answer 1

You can solve this issue with help of Java. For example, the Guava library can help us in solving this task.
Using report's parameter
We can add the parameter of java.util.Map type and use it for extracting the value by the key (it can be the value field from your sample)
The sample:
<?xml version="1.0" encoding="UTF-8"?>
<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="using_map" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="e566b23d-ca97-472e-9cc3-8073573f4537">
<import value="com.google.common.collect.*"/>
<import value="com.google.common.base.*"/>
<parameter name="values" class="java.util.Map" isForPrompting="false">
<defaultValueExpression><![CDATA[new ImmutableMap.Builder<String, String>().put("GD", "Good").put("AV", "Average").build()]]></defaultValueExpression>
</parameter>
<queryString>
<![CDATA[]]>
</queryString>
<field name="id" class="java.lang.String"/>
<field name="value" class="java.lang.String"/>
<columnHeader>
<band height="20">
<staticText>
<reportElement uuid="f23f6abc-cd9b-4415-a591-cb7a51ad0392" x="0" y="0" width="100" height="20"/>
<box>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement textAlignment="Center" verticalAlignment="Middle">
<font isBold="true" isItalic="true" isUnderline="false"/>
</textElement>
<text><![CDATA[Id]]></text>
</staticText>
<staticText>
<reportElement uuid="f23f6abc-cd9b-4415-a591-cb7a51ad0392" x="100" y="0" width="100" height="20"/>
<box>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement textAlignment="Center" verticalAlignment="Middle">
<font isBold="true" isItalic="true" isUnderline="false"/>
</textElement>
<text><![CDATA[Value]]></text>
</staticText>
<staticText>
<reportElement uuid="f23f6abc-cd9b-4415-a591-cb7a51ad0392" x="200" y="0" width="100" height="20"/>
<box>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement textAlignment="Center" verticalAlignment="Middle">
<font isBold="true" isItalic="true" isUnderline="false"/>
</textElement>
<text><![CDATA[Value from Map]]></text>
</staticText>
</band>
</columnHeader>
<detail>
<band height="20" splitType="Stretch">
<textField>
<reportElement uuid="8eb8bbef-430b-4ad1-b592-000fe7ccce9f" x="0" y="0" width="100" height="20"/>
<box leftPadding="10">
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement/>
<textFieldExpression><![CDATA[$F{id}]]></textFieldExpression>
</textField>
<textField>
<reportElement uuid="8eb8bbef-430b-4ad1-b592-000fe7ccce9f" x="100" y="0" width="100" height="20"/>
<box leftPadding="10">
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement/>
<textFieldExpression><![CDATA[$F{value}]]></textFieldExpression>
</textField>
<textField>
<reportElement uuid="8eb8bbef-430b-4ad1-b592-000fe7ccce9f" x="200" y="0" width="100" height="20"/>
<box leftPadding="10">
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement/>
<textFieldExpression><![CDATA[$P{values}.get($F{value})]]></textFieldExpression>
</textField>
</band>
</detail>
</jasperReport>
In this sample we use ImmutableMap.Builder class for creating and filling the Map.
The result will be (via iReport preview):
As you can see that the third columns contains null value for values that are not in Map.
Note: Don't forget to add Guava library to classpath.
Using scriptlet
You can do the same with help of Scriptlets.
You can write the simple Java class with static method, for example for getting value from the Map.
Using internationalization mechanism
May be the simplest way is to use report's internationalization support.
You can attach the properties file with values to your report.
The sample of jrxml:
<?xml version="1.0" encoding="UTF-8"?>
<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="localization" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" resourceBundle="marks" uuid="a5d74b61-8d62-41ac-b874-76d6f40da79e">
<queryString>
<![CDATA[]]>
</queryString>
<field name="id" class="java.lang.String"/>
<field name="value" class="java.lang.String"/>
<columnHeader>
<band height="20">
<staticText>
<reportElement uuid="f23f6abc-cd9b-4415-a591-cb7a51ad0392" x="0" y="0" width="100" height="20"/>
<box>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement textAlignment="Center" verticalAlignment="Middle">
<font isBold="true" isItalic="true" isUnderline="false"/>
</textElement>
<text><![CDATA[Id]]></text>
</staticText>
<staticText>
<reportElement uuid="f23f6abc-cd9b-4415-a591-cb7a51ad0392" x="100" y="0" width="100" height="20"/>
<box>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement textAlignment="Center" verticalAlignment="Middle">
<font isBold="true" isItalic="true" isUnderline="false"/>
</textElement>
<text><![CDATA[Value]]></text>
</staticText>
<staticText>
<reportElement uuid="f23f6abc-cd9b-4415-a591-cb7a51ad0392" x="200" y="0" width="114" height="20"/>
<box>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement textAlignment="Center" verticalAlignment="Middle">
<font isBold="true" isItalic="true" isUnderline="false"/>
</textElement>
<text><![CDATA[Value from Properties]]></text>
</staticText>
</band>
</columnHeader>
<detail>
<band height="20" splitType="Stretch">
<textField>
<reportElement uuid="8eb8bbef-430b-4ad1-b592-000fe7ccce9f" x="0" y="0" width="100" height="20"/>
<box leftPadding="10">
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement/>
<textFieldExpression><![CDATA[$F{id}]]></textFieldExpression>
</textField>
<textField>
<reportElement uuid="8eb8bbef-430b-4ad1-b592-000fe7ccce9f" x="100" y="0" width="100" height="20"/>
<box leftPadding="10">
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement/>
<textFieldExpression><![CDATA[$F{value}]]></textFieldExpression>
</textField>
<textField>
<reportElement uuid="8eb8bbef-430b-4ad1-b592-000fe7ccce9f" x="200" y="0" width="114" height="20"/>
<box leftPadding="10">
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement/>
<textFieldExpression><![CDATA[str($F{value})]]></textFieldExpression>
</textField>
</band>
</detail>
</jasperReport>
The marks.properties file:
GD=Good
AV=Average
VG=Very Good
And the result will be (with iReport preview):
I've used the str() method and the $R{} syntax.