Hibernate how to return Json value? - spring

Question

Hi I have this controller method that returns a list of customers and displays it using a model.
#Controller
public class timesheetController
{
#Autowired
private CustomerDAO customerDAO;
#GetMapping("/getCustomers")
public String getCustomers(Model view)
{
//get customers from dao
List<Customer> results = customerDAO.getCustomers();
//add the customers to the model
view.addAttribute("customers", results);
return "list-customers";
}
}
However I would like to return the list as a json to get an output like
{
"Customer_Code": T77A,
"Customer_Name": CustomerName1
},
{
"Customer_Code": T77B,
"Customer_Name": CustomerName2
}
I tried just returning the list as follows
#Controller
public class timesheetController
{
#Autowired
private CustomerDAO customerDAO;
#GetMapping("/getCustomers")
public List<Customer> getCustomers()
{
//get customers from dao
List<Customer> results = customerDAO.getCustomers();
return results;
}
}
but then I get this error as it seems to be expecting a view. How can I return the desired json output?

Answer 1

well you are trying to call getCustomers.jsp. What you want, instead, is not a JSP page but a JSON response. So you should make an AJAX call (by using JQuery or other framework or native JS)
So what I would do is change your Controller class in this way:
#Controller
public class timesheetController
{
#Autowired
private CustomerDAO customerDAO;
#GetMapping("/getCustomers", consumes = MediaType.APPLICATION_JSON_UTF8_VALUE, produces = {MediaType.APPLICATION_JSON_UTF8_VALUE })
public ResponseEntity<List<Customer>> getCustomers()
{
List<Customer> payload = customerDAO.getCustomers();
return ResponseEntity
.ok()
.contentType(MediaType.APPLICATION_JSON_UTF8)
.body(payload);
}
}
Then I would make the JSON call (I'm using JQuery in this example):
var baseUrl = YOUR_WEB_APP_CONTEXT/getCustomers;
$.ajax({
type: "GET",
url: baseUrl,
success: function(data) {
//All OK.. you should have the JSON response
},
error: function() {
//Something was wrong; you chould check
}
});