How to create JasperReports bar chart using JSON data?

Question

I have a report that is populated with JSON data. I'm now trying to figure out how to structure my JSON so that I can display some data in a pie chart. Can anyone provide an example of how I can use JSON data in a pie chart?

Answer 1

I figured it out! I needed to include a subDataset element defining my queryString:

<subDataset name="pieDataSet" whenResourceMissingType="Empty" uuid="6e90f719-ceb8-4ecd-9d24-4aa8e07f8e74">
    <parameter name="chartData" class="java.lang.String"/>
<queryString>
        <![CDATA[chartData]]>
</queryString>
    <field name="name" class="java.lang.String">
        <fieldDescription><![CDATA[name]]></fieldDescription>
    </field>
    <field name="value" class="java.lang.Integer">
        <fieldDescription><![CDATA[value]]></fieldDescription>
    </field>
</subDataset>

And then reference the subDataset in the pieChart element using a dataset and datasetRun element like this:

<pieChart>
    <chart isShowLegend="true" evaluationTime="Report">
        <reportElement x="50" y="0" width="200" height="200" uuid="6c0f07b9-47c5-4a3c-a06a-62b4acda0050"/>
        <box>
            <pen lineWidth="1.0"/>
        </box>
        <chartTitle position="Top">
            <titleExpression><![CDATA["My Pie chart"]]></titleExpression>
        </chartTitle>
        <chartSubtitle/>
        <chartLegend/>
    </chart>
    <pieDataset>
        <dataset>
            <datasetRun subDataset="pieDataSet" uuid="b115e88a-5865-4354-a765-6f629141fef5">
                <dataSourceExpression><![CDATA[((net.sf.jasperreports.engine.data.JsonDataSource)$P{REPORT_DATA_SOURCE}).subDataSource("chartData")]]></dataSourceExpression>
            </datasetRun>
        </dataset>
        <keyExpression><![CDATA[$F{name}]]></keyExpression>
        <valueExpression><![CDATA[$F{value}]]></valueExpression>
    </pieDataset>
    <piePlot>
        <plot/>
        <itemLabel/>
    </piePlot>
</pieChart>