I am trying to create a Hotel Room relationship where in post call I am trying to pass rooms array . Hoping to save the room in controller .
The problem i am facing right now is when i call /newhotel, a hotel is saved and it's associated rooms get saved. But those rooms have their hotel_id NULL. Why the association was not created at the time of saving the room ?
public class Hotel {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
#OneToMany(mappedBy = "hotel", cascade = CascadeType.ALL)
private List<Room> rooms;
}
public class Room {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne
#JoinColumn(name = "hotel_id")
private Hotel hotel;
#Enumerated(EnumType.STRING)
private RoomType roomType;
}
#RestController
public class HotelController {
#Autowired
HotelRepository hotelRepository;
#Autowired
RoomRepository roomRepository;
#CrossOrigin
#PostMapping(value = "/newhotel")
public Hotel addHotel(#RequestBody Hotel hotel) {
return hotelRepository.save(hotel);
}
}
Below is my post call request body :
{
"name" : "hotel1",
"rooms" : [
{
"roomType" : "SingleBed"
}
]
}
Related
I need to fetch names of all students who have enrolled for the courses.
Url:-/students/{course1}/{course2}
Eg /students/java/oracle
How to write controller, service and repository in rest api.
Entity:-
Student
Integer Id,String name and list coursenames
What about?
#Controller
#RequestMapping("/students")
public class StudentController {
#Autowired
private StudentService studentService;
// /students/java,oracle
#GetMapping(value="/{courses}")
#ResponseBody
public String getStudents(#PathVariable String[] courses) {
return studentService.getStudents(courses);
}
}
Student
#Entity
#Table(name = "student")
public class StudentDao {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
#OneToMany(fetch = FetchType.EAGER)
#Fetch(value = FetchMode.SUBSELECT)
#JoinColumn(name = "id", referencedColumnName = "id")
private List<CourseDao> course;
}
Course
#Entity
#Table(name = "course")
public class CourseDao {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
}
In my opinion it is bad rest design. I'll create POST endpoint with body, which contains array with course Id's and find students by course id's.
If the parameters are optional or an array you shouldn't use a path variable but use a request parameter.
I have two simple classes Student and Course. I am trying to set up many to many relationship between these classes. I want to use additional table whose PRIMARY KEY is the combination of the primary keys of student and course tables (student_id and course_id).
The student class:
#Entity
#Table(name = "student")
#Getter
#Setter
#AllArgsConstructor
#NoArgsConstructor
public class Student {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Column(name = "name")
private String name;
#Column(name = "surname")
private String surname;
#OneToMany(mappedBy = "student")
private Set<CourseStudent> courses;
}
The course class:
#Entity
#Table(name = "course")
public class Course {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String courseName;
#OneToMany(mappedBy = "course")
Set<CourseStudent> students;
}
The entity that stores the relationship between course and the student:
#Entity
#NoArgsConstructor
#Data
public class CourseStudent {
#EmbeddedId
CourseStudentKey id;
#ManyToOne
#MapsId("studentId")
#JoinColumn(name = "student_id")
Student student;
#ManyToOne
#MapsId("courseId")
#JoinColumn(name = "course_id")
Course course;
public CourseStudent(Student student, Course course) {
this.student = student;
this.course = course;
this.rating = 0;
}
int rating;
}
Attention: Since I want to have additional features in this entity (for example, storing the rating of the students for courses), I don't want to use #JoinTable idea that we implement in the Student class.
Since I have multiple attributes in the primary key of CourseStudent entity, I used the following class
#Embeddable
#Data
public class CourseStudentKey implements Serializable {
#Column(name = "student_id")
Long studentId;
#Column(name = "course_id")
Long courseId;
}
I have the following POST request to insert the student into a course:
#PostMapping("/insert/students/{studentId}/courses/{courseId}")
public CourseStudent insertStudentIntoCourse(#PathVariable(value = "studentId") Long studentId,
#PathVariable(value = "courseId") Long courseId) {
if (!studentRepository.existsById(studentId)) {
throw new ResourceNotFoundException("Student id " + studentId + " not found");
}
if (!courseRepository.existsById(courseId)) {
throw new ResourceNotFoundException("Course id " + courseId + " not found");
}
CourseStudent courseStudent = new CourseStudent(
studentRepository.findById(studentId).get(),
courseRepository.findById(courseId).get()
);
return courseStudentRepository.save(courseStudent);
}
I have manually added Student and the Course into my local database and send this request by using Postman.
http://localhost:8080/insert/students/1/courses/1
However, I get the following error:
{
"timestamp": "2022-08-04T12:33:18.547+00:00",
"status": 500,
"error": "Internal Server Error",
"path": "/insert/students/1/courses/1"
}
In the console, I get NullPointerException. What is the thing I am doing wrong here?
*#Entity
#Table(name = "model_data")
public class ModelData {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne
#JoinColumn(name = "diagram_id")
private DiagramEntity diagram;
//Getter Setter
}
#Entity
#Table(name = "diagram")
public class DiagramEntity {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#JsonProperty(value = "class")
private String aciklama;
#OneToMany(mappedBy = "diagram")
private Set<ModelData> modelData;
//Getter Setter
}*
DiagramEntity has manytoone relation with modeldata entity. Then I post
*{
"modelData": [
{
"diagram": null,
}
],
}*
via postman, DiagramEntity id is automatically updated but I cannot assign id to modelData entity and cannot save to database. what should I do?
I find solution for my problem. I streamed every object and mapped to my entities in the my controller class.
public DiagramEntityDto saveOrUpdate(#RequestBody DiagramEntityDto dto) {
try {
dto.getModelData().stream().map(a ->
this.modelDataService.saveOrUpdate(a)).collect(Collectors.toSet());
return this.diagramService.saveOrUpdate(dto);
} catch (Exception e) {
System.out.println(e.getMessage());
}
return null;
}
I have created two Entities namely Teacher and Detail, the code snippet is shown below
Teacher.java
#Entity
#Table(name = "teacher")
public class Teacher implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private long id;
#Column(name = "name")
private String name;
#Column(name = "age")
private int age;
#OneToOne(mappedBy = "teacher", cascade = CascadeType.ALL)
private Detail detail;
public Teacher() {
}
public Teacher(String name, int age) {
this.name = name;
this.age = age;
}
//getter and setter
}
Detail.java
#Entity
#Table(name = "detail")
public class Detail implements Serializable {
#Id
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "id")
private Teacher teacher;
#Column(name = "subjects")
private String subjects;
public Detail() {
}
public Detail(String subjects) {
this.subjects = subjects;
}
//getter and setter
}
I am trying to achieve one to one mapping with the shared primary key concept
but when i execute the controller, only Teacher table is updating with the value
try {
Teacher teacher=new Teacher("xyz",23);
Detail detail=new Detail("Java,c,c++");
teacher.setDetail(detail);
session.beginTransaction();
session.save(teacher);
session.getTransaction().commit();
model.addAttribute("added", "data inserted");
session.close();
}
After executing only Teacher table is updated with the specified values.Detail table is still showing empty
It does not work exactly like that. You still need the id field in your Detail, so add:
#Id
private long id;
to your Deatail class.
And - as comment suggests - replace the #Id annotation in field Teacher to #MapsId. This way the id of Teacher is mapped to the id of Detail BUT ONLY if you also set the teacher to the detail - you always need to set both sides of relationship - like:
teacher.setDetail(detail);
detail.setTeacher(teacher);
I have 2 tables 'orders' and 'orderlines' and used bidirectional OneToMany mapping.When i save the order, record is successfully inserted into table 'orders'.But my 'orderlines' table is empty.No record is inserted.
This is the save operation code in Controller.
#RequestMapping(value = "ordersuccess", method = RequestMethod.POST)
public String processOrder(#ModelAttribute("order") Order order,
#ModelAttribute("cart") Cart cart,
BindingResult result) {
if (!result.hasErrors()) {
Set<OrderLine> orderLines = new HashSet<OrderLine>();
for(CartLine c : cart.getCartLines()) {
OrderLine line = new OrderLine();
line.setOrder(order);
line.setProduct(c.getProduct());
line.setProductPrice(c.getProduct().getPrice());
line.setTotalPrice(c.getPrice());
orderLines.add(line);
order.setOrderLines(orderLines);
}
orderService.save(order);
orderLineService.save(orderLine);
}
return "ordersuccess";
}
Can someone point me what wrong i am doing.
EDIT:
OrderLine.java
public class OrderLine {
#Id
#GeneratedValue
#Column(name="orderline_id")
private int orderline_id;
#ManyToOne
#JoinColumn(name = "order_id")
private Order order;
#ManyToOne(targetEntity = Product.class,
cascade = CascadeType.ALL,
fetch = FetchType.LAZY)
#JoinTable(
name="products",
joinColumns=#JoinColumn(name="product_id")
)
private Product product;
)
Order.java
public class Order {
#Id
#GeneratedValue
#Column(name="id")
private int id;
#OneToMany(mappedBy = "order")
private Set<OrderLine> orderLines;
//getter/setter
The orderLines object is created:
Set<OrderLine> orderLines = new HashSet<OrderLine>();
You then add lines to it:
orderLines.add(line);
But it never attributed to an order or sent to the service layer.
Also the OrderLine.product mapping should be like this
public class OrderLine {
#Id
#GeneratedValue
#Column(name="orderline_id")
private int orderline_id;
#ManyToOne
#JoinColumn(name = "order_id")
private Order order;
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "product_id")
private Product product;
}
and Order.orderLines should have a cascade:
public class Order {
#Id
#GeneratedValue
#Column(name="id")
private int id;
#OneToMany(mappedBy = "order", cascade = CascadeType.ALL)
private Set<OrderLine> orderLines;
}
You then need to save the orderLines:
order.setOrderLines(orderLines);
and save the order:
orderService.save(order);
When order is saved it will cascade the orderlines and the associated product too.
If you have bidirectional associations don't forget to set both sides.