In Spring MVC how to return JSON of multiple POJO classes

Question

I have a project in which I have multiple POJO classes.These classes are mapped with database using Hibernate.I want to return data from database in JSON.My code is:

@RequestMapping(value="{userid}",method=RequestMethod.GET)
public @ResponseBody List<IterationInfo> getIterationInfoInJSON(@PathVariable int userid) 
{
    Configuration con = new Configuration();
    con.configure("hibernate.cfg.xml");

    SessionFactory SF = con.buildSessionFactory();
    Session session= SF.openSession();
    Transaction TR = session.beginTransaction();
    Query query=session.createQuery("from IterationInfo");
    List<IterationInfo> listiterationinfo=query.list();
    session.close();

    SF.close();
    return listiterationinfo;
}

IterationInfo is a POJO class.List has the data from the query.But I want data from multiple Tables/POJO classes as a single JSON.I am able to return data from IterationInfo table.But how to return from multiple tables/POJO classes.

Answer 1

Create a wrapper dto containg all the data you need, for example:

class SomeResponseDto {
    private List<IterationInfo> iterationInfo;
    private List<AnotherPojoClass> anotherPojoClasses;
    // getters, setters
}

And now you can combine your data into single JSON object:

@RequestMapping(value="{userid}",method=RequestMethod.GET)
public @ResponseBody SomeResponseDto getIterationInfoInJSON(@PathVariable int userid) {
    // code
    SomeResponseDto dto = new SomeResponseDto();
    dto.setIterationInfos(listiterationinfo);
    dto.setAnotherPojoClasses(anotherPojoClasses);
    return dto;
}

Answer 2

Class A{ //POJO Class 1
  private String id;
  private String name;
  //Getter and setter methods
}
Class B{ //POJO Class 2
  private String id;
  private String name;
  //Getter and setter methods
}

Create object for the POJO classes.

@RequestMapping(value="{userid}",method=RequestMethod.GET)
public @ResponseBody List<Object> getIterationInfoInJSON(@PathVariable int userid) 
{
  A a=new A(); B b=new B();
  List<Object> ls=new List<Object>();
  ls.add(a);
  ls.add(b);
  return ls;
}