How To: Generating Table Report via JSON data-source in Jasper Report

Recently, I got a chance to generate reports using JSON data source in Jasper Report via Java Spring application. As I was newbie in Jasper Report; I tried to find out tutorials to get started with JSON data source and populate JSON data in table. I thought it will be smooth but its not; you need to do some configuration in JRXML to populate the data fields. In this How - To, I will try to explain how to setup JSON data source and pull data field in iReport (Jasper Report - Report Designer Tool) and then generate a table.

 Note: For Java 8 users, refer this link to open iReport http://stackoverflow.com/questions/23902977/ireport-not-starting-using-jre-8

First we create static JSON file student.json:
[{"name" : "ABC", "age" : 23, "address" : "11 street", "taking_hostel" : "No"},{"name" : "DEF", "age" : 22, "address" : "1 street", "taking_hostel" : "Yes"},{"name" : "GHI", "age" : 25, "address" : "153 street", "taking_hostel" : "No"},{"name" : "JKL", "age" : 23, "address" : "141 street", "taking_hostel" : "Yes"},{"name" : "MNO", "age" : 25, "address" : "121 street", "taking_hostel" : "Yes"},{"name" : "QPR", "age" : 25, "address" : "21 street", "taking_hostel" : "No"},{"name" : "STU", "age" : 26, "address" : "31 street", "taking_hostel" : "No"},{"name" : "VWX", "age" : 23, "address" : "11 street", "taking_hostel" : "No"},{"name" : "YZA", "age" : 23, "address" : "10 street", "taking_hostel" : "No"}]

Now we create JSON data source in iReport:
Click on to setup a JSON data source. Give the name of data source and browse to above created JSON file and test the connection.

Click on save to save the changes and select JSON data source in

Now we create report template:
Select File > New > Report (Side Navigation) > Blank A4 Landscape
Give the name of report template, I named it as test.jrxml. After clicking on finish various options of  report designer will open.

Now we pull JSON data in iReport:
If you click on DB pull icon  which you will find here:

In Report query tab (opens by default) select query language JSON and click on "Read Fields"; you will get a message "You must insert a valid query first" and on "Preview data" you will not see any data.
That's the problem with iReport JSON datasource, it is not pulling JSON data by default.For that we need to do a below configuration in XML above the <background> tag:

1. <queryString language="json">
2. <![CDATA[]]>
3. </queryString>
4. <field name="name" class="java.lang.String">
5. <fieldDescription><![CDATA[name]]></fieldDescription>
6. </field>
7. <field name="age" class="java.lang.Integer">
8. <fieldDescription><![CDATA[age]]></fieldDescription>
9. </field>
10. <field name="address" class="java.lang.String">
11. <fieldDescription><![CDATA[address]]></fieldDescription>
12. </field>
13. <field name="taking_hostel" class="java.lang.String">
14. <fieldDescription><![CDATA[taking_hostel]]></fieldDescription>
15. </field>

Now, if you click again on DB pull icon, you should see fields and JSON data.

Now we create a new data set for table:
In Report Inspector, right click on template name you will get a option of "Add Dataset". It will open a New Dataset dialog box.

1. Provide the dataset name and check radio button of "Create new dataset from a connection or datasource". 
2. In step 2 select JSON datasource. 
3. In step 3 you will find Fields empty.(It's okay we will fix that later)
4. Click on Finish and new dataset will be created.  

To fix the issue on step 3, we need to put below code in JRXML:

1. In JRXML you will find below tag or search for dataset name which you have created in previous step.
   <subDataset name="New Dataset 1" uuid="27346b8c-b84e-453c-a586-ba7a7293056e"/>
2. In this sub data set we need to put fields of our JSON
3. Update the sub data set with below code:
   
   1. <subDataset name="New Dataset 1" uuid="27346b8c-b84e-453c-a586-ba7a7293056e">
   2. <queryString language="json">
   3. <![CDATA[]]>
   4. </queryString>
   5. <field name="name" class="java.lang.String">
   6. <fieldDescription><![CDATA[name]]></fieldDescription>
   7. </field>
   8. <field name="age" class="java.lang.Integer">
   9. <fieldDescription><![CDATA[age]]></fieldDescription>
   10. </field>
   11. <field name="address" class="java.lang.String">
   12. <fieldDescription><![CDATA[address]]></fieldDescription>
   13. </field>
   14. <field name="taking_hostel" class="java.lang.String">
   15. <fieldDescription><![CDATA[taking_hostel]]></fieldDescription>
   16. </field>
   17. </subDataset>

Now we create a table:

1. To create a table, drag "Table" from Palette to Detail 1 band.
2. It will open a dialog box and will ask you to select the data set. I have selected "New Dataset 1" and click on next.
3. Select all the fields.
4. In connection step, select "Use a JRDatasource expression" and put $P{REPORT_DATA_SOURCE} in text box.
5. In "Table Style"  select appropriate table header. I have selected only "Add Column Header".
6. Click on finish to complete the table configuration. 

Now expand the table band in detail 1 band in designer tab.On click on preview you should able to see the table filled with JSON data.

To use this template in java code, right click on template name in Report Inspector, goto properties and select language as java.

Initially we created a static JSON file to replicate the desire column names in report; we can put dynamic data in this template via Java Spring application.

Hope this helps.