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.
Related
Click Link for pic
Please help I am stuck in error after error
Need to create a spring data model and pass the test case
Spring data models are
#Entity
public class Cart {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer cartId;
private Double totalAmount;
#OneToOne
#JoinColumn(name = "userId")
private User user;
#OneToMany(mappedBy = "cart")
private List<CartProduct> cartProducts;
//getter and setter and constructor
}
#Entity
public class CartProduct {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer cpId;
#ManyToOne
#JoinColumn(name = "cartId")
private Cart cart;
#ManyToOne
#JoinColumn(name = "productId")
private Product product;
private Integer quantity = 1;
//getter and setter and constructor
}
#Entity
public class Category {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer categoryId;
private String categoryName;
//getter and setter and constructor
}
#Entity
public class Product {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer productId;
private String productName;
private Double price;
#ManyToOne
#JoinColumn(name ="userId")
private User seller;
#ManyToOne
#JoinColumn(name ="userId")
private Category category;
//getter and setter and constructor
}
The main issue is role and user can't able to create
many-to-many relations
#Entity
public class Role {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
Integer roleId;
String role;
#ManyToMany(mappedBy = "roles")
Set<User> users = new HashSet<>();
//getter setter and constructor
}
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer userId;
private String username;
private String password;
// Implement Roles
#ManyToMany
#JoinTable(name="user_Role",joinColumns = #JoinColumn(name="userId")
,inverseJoinColumns = #JoinColumn(name="roleId"))
private Set<Role> roles = new HashSet<Role>();
}
https://pastebin.com/T34SbwMy
the test case is in the link and can't able to pass the test case.
Thanks in advance.
I have 2 entities as below:
Course
#Entity
public class Course {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#OneToMany(mappedBy = "course", cascade = {CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.MERGE})
private List<Comment> comments;
Comment
#Entity
public class Comment {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String comment;
#ManyToOne(targetEntity = Course.class)
private Course course; //Error: 'Many To One' attribute type should not be 'Course'
I follow luv2code.com course but he use Spring MVC and it work just find, but when I do this in spring boot, it always show the error, please help me fix this!
Try something like this:
#Entity
public class Course {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#OneToMany(mappedBy = "course")
private List<Comment> comments;
And your comment entity:
#Entity
public class Comment {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String comment;
#ManyToOne(cascade = CascadeType.ALL)
private Course course;
#Entity
public class Course {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#OneToMany(cascade = CascadeType.ALL,
fetch = FetchType.LAZY,
orphanRemoval = true)
private List<Comment> comments = new ArrayList<Comment>();
#Entity
public class Comment {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String comment;
}
You don't to define ManyToOne Mapping in your comment Entity.
I have two entity with name of the article and article Category.
and they have one-to-many relationships.
I use #JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class,property = "id")
but I cant see data of article category(category_id) in spring data rest.
ArticleCategory.class
#Entity
#Table(name = "article_category")
#Getter
#Setter
public class ArticleCategory implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name = "category_name")
private String categoryName;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "articleCategory", fetch = FetchType.LAZY)
private Set<Article> articles = new HashSet<>();
}
Article.class
#Entity
#Table(name = "article")
#Getter
#Setter
#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id")
public class Article implements Serializable {
public Article() {
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "category_id", nullable = false)
private ArticleCategory articleCategory;
#Column(name = "title")
private String title;
#Column(name = "image_url")
private String image_url;
#Column(name = "short_description")
private String short_description;
#Column(name = "text")
private String text;
#Column(name = "keywords", nullable = true)
private String keywords;
#Column(name = "visit", nullable = false)
private int visit;
#Column(name = "code", nullable = false)
private UUID code;
#Column(name = "date_created")
#CreationTimestamp
private Date dateCreated;
#Column(name = "date_updated", nullable = false)
#UpdateTimestamp
private Date dateUpdated;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "user_id")
private User user;
public Article(String title, String image_url, String short_description, String text, String keywords, int visit, UUID code) {
this.title = title;
this.image_url = image_url;
this.short_description = short_description;
this.text = text;
this.keywords = keywords;
this.visit = visit;
this.code = code;
}
}
Article Repository
#CrossOrigin("http://localhost:4200")
#RepositoryRestResource(collectionResourceRel = "article", path = "article")
public interface ArticleRepository extends JpaRepository<Article,Long> {
Article findByCode(UUID uuid);
}
And this is output of spring data rest
enter image description here
That is exactly because you used #JsonManagedReference and #JsonBackReference. Keep in mind the following when using them:
#JsonManagedReference is the forward part of the relationship and is the one that gets serialized normally.
#JsonBackReference is the back part of the relationship and it will be omitted from serialization.
The serialized Article object does not contain a reference to the ArticleCategory object.
If you want to have any ArticleCategory data when serializing Article you can either use #JsonIdentityInfo so that one of the properties is serialized (in this case I've chosen id for both):
#Entity
#Table(name = "article")
#Getter
#Setter
#JsonIdentityInfo(
generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id")
public class Article implements Serializable{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "category_id", nullable = false)
private ArticleCategory articleCategory;
}
#Entity
#Table(name = "article_category")
#Getter
#Setter
#JsonIdentityInfo(
generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id")
public class ArticleCategory implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name = "category_name")
private String categoryName;
#OneToMany(cascade = CascadeType.ALL,mappedBy = "articleCategory" ,fetch = FetchType.LAZY)
private Set<Article> articles=new HashSet<>();
}
If you are only interested in categoryId another possibility would be to use #JsonIgnore on private Set<Article> articles property so that it is not serialized:
#Entity
#Table(name = "article_category")
#Getter
#Setter
public class ArticleCategory implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name = "category_name")
private String categoryName;
#JsonIgnore
#OneToMany(cascade = CascadeType.ALL,mappedBy = "articleCategory" ,fetch = FetchType.LAZY)
private Set<Article> articles=new HashSet<>();
}
If none of those suits your needs you might need to implement your own custom serializer. You can read more about all those options at https://www.baeldung.com/jackson-bidirectional-relationships-and-infinite-recursion.
I solved the problem using the controller
And that's why #JsonManageRefrence and #JsonBackRefrence do not work
I replaced the lazy load with the eager load in both entity
#ManyToOne(fetch = FetchType.Eager)
#JoinColumn(name = "user_id")
#JsonManageRefrence
private User user;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "articleCategory",
fetch = FetchType.Eager)
#JsonBackRefrence
private Set<Article> articles = new HashSet<>();
and then add a controller
package com.example.demo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
#RestController
#RequestMapping("/getAllArticle")
public class MyController {
private ArticleRepository articleRepository;
// you must do constructor injection
#GetMapping("/getAllArticle")
public List<Article> allArticle()
{
return articleRepository.findAll();
}
}
I use OneToOne in the spring data JPA and I want to delete a record from the Address table without touching the user. But I can't.
If I remove User, in this case Address is removed, that's good.
But how can you delete an Address without touching the User?
https://github.com/myTestPercon/TestCascade
User.Java
#Entity
#Table(name = "user", schema = "testCascade")
public class User implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
#OneToOne(mappedBy = "user", cascade = CascadeType.ALL)
private Address address;
// Getter and Setter ...
}
Address.java
#Entity
#Table(name = "address", schema = "testCascade")
public class Address implements Serializable {
#Id
private Long id;
#Column(name = "city")
private String city;
#OneToOne
#MapsId
#JoinColumn(name = "id")
private User user;
// Getter and Setter ...
}
DeleteController.java
#Controller
public class DeleteController {
#Autowired
ServiceJpa serviceJpa;
#GetMapping(value = "/deleteAddressById")
public String deleteAddressById () {
serviceJpa.deleteAddressById(4L);
return "redirect:/home";
}
}
You got your mapping wrong thats all is the problem .
try the below and see
User.java
#Entity
#Table(name = "user", schema = "testCascade")
public class User implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
#OneToOne(cascade=CascadeType.ALL)
#JoinColumn(name="foriegn key column in user table for address example.. address_id")
private Address address;
// Getter and Setter ...
}
Address.java
#Entity
#Table(name = "address", schema = "testCascade")
public class Address implements Serializable {
#Id
private Long id;
#Column(name = "city")
private String city;
//name of the address variable in your user class
#OneToOne(mappedBy="address",
cascade={CascadeType.DETACH, CascadeType.MERGE, CascadeType.PERSIST,
CascadeType.REFRESH})
private User user;
// Getter and Setter ...
}
In order to solve this problem, you need to read the hibernate Documentation Hibernate Example 162, Example 163, Example 164.
And also I recommend to look at this is Using #PrimaryKeyJoinColumn annotation in spring data jpa
This helped me in solving this problem.
And also you need to specify the parameter orphanRemoval = true
User.java
#Entity(name = "User")
#Table(name = "user", schema = "testother")
public class User implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
#OneToOne(mappedBy = "user", cascade = CascadeType.ALL, orphanRemoval = true)
private Address address;
public void addAddress(Address address) {
address.setUser( this );
this.address = address;
}
public void removeAddress() {
if ( address != null ) {
address.setUser( null );
this.address = null;
}
}
// Getter and Setter
}
Address.java
#Entity(name = "Address")
#Table(name = "address", schema = "testother")
public class Address implements Serializable {
#Id
private Long id;
#Column(name = "city")
private String city;
#OneToOne
#MapsId
#JoinColumn(name = "id")
private User user;
// Getter and Setter
}
DeleteController .java
#Controller
public class DeleteController {
#Autowired
ServiceJpa serviceJpa;
#GetMapping(value = "/deleteUser")
public String deleteUser () {
User user = serviceJpa.findUserById(2L).get();
user.removeAddress();
serviceJpa.saveUser(user);
return "/deleteUser";
}
}
Or make a custom SQL query.
#Repository
public interface DeleteAddress extends JpaRepository<Address, Long> {
#Modifying
#Query("delete from Address b where b.id=:id")
void deleteBooks(#Param("id") Long id);
}
public class Address {
#Id
private Long id;
#MapsId
#JoinColumn(name = "id")
private User user;
}
Rename #JoinColumn(name = "id") to #JoinColumn(name = "user_id")
You can't say that the column that will point to user will be the id of the Address
I'm starting to learn Spring Java Framework . I created some Enity to join 2 Model like my Database. And now I want to insert to Join Table by JpaRepository. What i have to do?
This is my Code (Please fix help me me if something is not right)
Model Users_RoomId to define Composite Primary Key
#Embeddable
public class Users_RoomId implements Serializable {
private static final long serialVersionUID = 1L;
#Column(name = "ID_room", nullable = false)
private String idRoom;
#Column(name = "user_id", nullable = false)
private int idUser;
}
Model Users_Room to join 2 Model Users and Room
#Entity
#Table(name ="bookroom")
public class Users_Room {
#EmbeddedId
private Users_RoomId usersroomId;
#ManyToOne
#MapsId("idRoom")
private Room room;
#ManyToOne
#MapsId("idUser")
private Users users;
#Column(name = "Bookday")
private String bookday;
Model Users and Room I used annotation #OneToMany
Model Users
#Entity
#Table(name = "users")
public class Users implements Serializable{
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "user_id", nullable = false)
private int id;
#Column(name = "name", nullable = false)
private String name;
#Column(name = "email")
private String email;
#Column(name = "pass")
private String pass;
#Column(name = "role")
private int role;
#OneToMany(mappedBy = "users")
private List<Users_Room> user;
Model Room
#Entity
#Table(name ="room")
public class Room implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "ID_room", nullable = false)
private String id;
#Column(name = "name_room", nullable = false)
private String name;
#Column(name = "Description")
private String describe;
#ManyToOne
#JoinColumn(name = "ID_status")
private Status status;
#Column(name = "room_image")
private String image;
public Room() {
super();
}
#ManyToOne
#JoinColumn(name = "ID_kind")
private KindRoom kind;
#OneToMany(mappedBy = "room")
private List<Users_Room> rooms;
This is my database
So I don't know how to insert a new bookroom with iduser,idroom and bookday with JPA repository.. It'necessary to write Query in JPARepository or We just need to use method save() to insert data
Thanks everyone
I had same problem and solved with following code. I used method save() to insert data. Following code is 'createRoom' method in 'RoomService.java'.
RoomService.java
private final RoomRepository roomRepository;
private final UserRoomRepository userRoomRepository;
private final UserRepository userRepository;
public RoomService(RoomRepository roomRepository, UserRoomRepository userRoomRepository, UserRepository userRepository) {
this.roomRepository = roomRepository;
this.userRoomRepository = userRoomRepository;
this.userRepository = userRepository;
}
#Transactional
public RoomDto createRoom(Long userId, Long chattingUserId) {
Room room = roomRepository.save(new Room());
room.addUserRoom(userRepository.findById(userId).orElseThrow(()->new NoSuchElementException("No User")));
room.addUserRoom(userRepository.findById(chattingUserId).orElseThrow(()->new NoSuchElementException("No User")));
userRoomRepository.save(new UserRoom(userRepository.findById(userId).orElseThrow(()->new NoSuchElementException("No User")),room));
userRoomRepository.save(new UserRoom(userRepository.findById(chattingUserId).orElseThrow(()->new NoSuchElementException("No User")),room));
RoomDto roomDto = RoomDto.of(room);
return roomDto;
}