parse and map json using postman

Question

@Controller
public class StudentRegistrationController {

@RequestMapping(method = RequestMethod.POST, value="/register/reg")
@ResponseBody
StudentRegistrationReply registerStudent(@RequestBody Student student) {
    System.out.println("In registerStudent");
    StudentRegistrationReply stdregreply = new StudentRegistrationReply();           

    StudentRegistration.getInstance().add(student);

    //We are setting the below value just to reply a message back to the caller
    stdregreply.setId(student.getId());
    stdregreply.setName(student.getName());
    stdregreply.setAge(student.getAge());
    stdregreply.setRegistrationNumber(student.getRegistrationNumber());
    stdregreply.setPayment_detailsList(student.getPayment_detailsList());
    stdregreply.setRegistrationStatus("Successful");

    daocontroller.setStudentRegistration(stdregreply);
    return stdregreply;

}

}

trying to map the postman request to but getting null

json is like

{ 
    "id": 300,
    "name": "kukri",
    "age": 26,
    "registrationNumber": "54326",
    "Student_payment_details":
    {
      "pay": 50000,
      "date": "23061994",
      "phcounter": "SKB"
    }

}

Java classes

public class Student {
    private int id;
    private String name;
    private int age;
    private String registrationNumber;
    private Student_payment_details payment_detailsList; //getter and setter
}

Answer 1

1. Using Lombok as my getter/setters, you can ignore it and write your own getters/setters
2. There is issue with the body of your request, you should pass key in json as java variable name, you are passing Student_payment_details instead of payment_detailsList
3. Getters and Setters should be with respect to your variable name.

Request url:

curl -X POST \
  http://localhost:8080/register/reg \
  -H 'Content-Type: application/json' \
  -H 'cache-control: no-cache' \
  -d '{
  "id": 300,
  "name": "kukri",
  "age": 26,
  "registrationNumber": "54326",
  "payment_detailsList": {
    "pay": 50000,
    "date": "23061994",
    "phcounter": "SKB"
  }
}'

Java Dtos:

import lombok.Data;

@Data
public class Student_payment_details {
    int pay;
    String date;
    String phcounter;
}

import lombok.Data;

@Data
public class Student {
    private int id;
    private String name;
    private int age;
    private String registrationNumber;
    private Student_payment_details payment_detailsList; //getter and setter
}

Following image shows the content of a student variable populated inside the controller

Note: I do not know your use case but as a general suggestion, please follow 1 type of naming convention,snake_case or camelCase.
In java mostly used is camelCase.
Also naming of the variable should be similar to the class type,
here variable payment_detailsList is of type Student_payment_details which leads to confusion, if you want JSON variable name to be different then you can use as

 @JsonProperty("payment_detailsList")
 private Student_payment_details student_payment_details;