Error is:
at jdk.proxy2/jdk.proxy2.$Proxy106.save(Unknown Source) ~[na:na] at
com.example.OneToManyUniDirectional.service.concretes.AuthorManager.addAuthor(AuthorManager.java:50)
~[classes/:na] at
com.example.OneToManyUniDirectional.controller.AuthorController.addAuthors(AuthorController.java:21)
~[classes/:an]
I have no idead why this happening.
Author class:
public class Author {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name="name")
private String firstName;
#Column(name="surname")
private String lastName;
#OneToMany(cascade=CascadeType.MERGE,fetch = FetchType.EAGER)
private Set<Book> books=new HashSet<>();
}
Book Class:
public class Book {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String isbn;
#Column(name="book_name")
private String name;
}
addAuthor method
#Override
public void addAuthor(CreateAuthor createAuthor){
// Book book=new Book();
Author author=new Author();
author.setFirstName(createAuthor.getFirstName());
author.setLastName(createAuthor.getLastName());
if(this.bookRepository.findById(createAuthor.getBook().getId()).isPresent()){
UpdateBook updateBook=new UpdateBook();
updateBook.setName(createAuthor.getBook().getName());
updateBook.setIsbn(createAuthor.getBook().getIsbn());
this.bookService.updateBook(updateBook,createAuthor.getBook().getId());
}
else{
CreateBook createBook=new CreateBook();
createBook.setName(createAuthor.getBook().getName());
createBook.setIsbn(createAuthor.getBook().getIsbn());
this.bookService.addBook(createBook);
author.getBooks().add(createAuthor.getBook());
}
this.authorRepository.save(author);
}
Create Author:
#Data
#NoArgsConstructor
#AllArgsConstructor
public class CreateAuthor {
private String firstName;
private String lastName;
private Book book;
}
Controller
#PostMapping("/authors")
public void addAuthors(#RequestBody CreateAuthor createAuthor){
this.authorService.addAuthor(createAuthor);
}
Also create book and updateBook classes does not has id properties in it.
Related
I am getting this error .
Cannot call sendError() after the response has been committed
Can someone help me figure out why?.
#Entity
public class Product {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#OneToOne(
fetch = FetchType.LAZY,
cascade = CascadeType.ALL
)
#JoinColumn(name = "details_id")
private Details details;
//Getters and setters left out for brevity
}
#Entity
public class Details {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
private String description;
private float price;
private float discount;
#OneToOne(mappedBy = "details")
private Product product;
}
#RestController
public class ProductController {
#Autowired
ProductRepository productRepository;
#GetMapping("/getAllProducts")
public Iterable<Product> getAllProducts(){
return productRepository.findAll();
}
}
#RestController
public class DetialsController {
#Autowired
ProductRepository productRepository;
#Autowired
DetailsRepository detailsRepository;
#PostMapping("/details")
public Details addDetails(#RequestBody Details details) {
Product newProduct = new Product();
newProduct.setDetails(details);
productRepository.save(newProduct);
return detailsRepository.save(details);
}
}
I am able to make the POST call to /details; for adding details successfully. But when i make GET call to /getAllProducts, I am getting this error
Cannot call sendError() after the response has been committed
This is an issue with bidirectional relationships, as they hold references to each other, at deserialization, Jackson runs in an infinite loop. My first suggestion would be adding #JsonIgnore to one end of the relation.
#OneToOne(mappedBy = "details")
#JsonIgnore
private Product product;
Afterward, if that solved your issue, you can look over #JsonManagedReference/#JsonBackReference and #JsonIdentityInfo.
You can also look over this link for more insight
You can use this :
#Entity
public class Product {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#JsonBackReference(value = "details_id")
#OneToOne(
fetch = FetchType.LAZY,
cascade = CascadeType.ALL
)
#JoinColumn(name = "details_id")
private Details details;
//Getters and setters left out for brevity
}
#Entity
public class Details {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
private String description;
private float price;
private float discount;
#JsonManagedReference(value = "details")
#OneToOne(mappedBy = "details",,cascade=CascadeType.ALL)
private Product product;
}
I have a Post entity
#Entity
public class Post {
#Id
private UUID id;
#NotNull
private String title;
#NotNull
private String content;
#NotNull
private String identifier;
#NotNull
private String category;
#NotNull
#Column(name = "created_at")
private Date createdAt;
#NotNull
#Column(name = "updated_at")
private Date updatedAt;
public Post (){
}
public Post (String title, String content, String category){
this.title = title;
this.content = content;
this.category = category;
}
// rest of the getters and setters
}
And this is my Comment entity:
#Entity
public class Comment {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private UUID id;
#NotNull
private String name;
#NotNull
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer identifier;
#NotNull
private String email;
#NotNull
private String content;
#NotNull
#ManyToOne
#JoinColumn(name = "post_id")
private Post postId;
#NotNull
#Column(name = "created_at")
private Date createdAt;
public Comment() {
}
public Comment(String name, String email, String content){
this.name = name;
this.email = email;
this.content = content;
}
}
And this is my post controller:
#RestController
#RequestMapping("/posts")
public class PostController {
private String getIdentifier(String str){
return String.join("-", str.split(" "));
}
#Autowired
private PostService postService;
#RequestMapping(value = "", method = {GET, HEAD})
public List<Post> getAllPosts(){
return postService.getAllPosts();
}
#RequestMapping(value = "", method = {POST, OPTIONS})
public Post addNewPost(#RequestBody Post post){
post.setId(UUID.randomUUID());
post.setIdentifier(this.getIdentifier(post.getTitle()));
post.setCreatedAt(new Date());
post.setUpdatedAt(new Date());
return postService.savePost(post);
}
#RequestMapping(value = "/{id}", method = {GET, HEAD})
public Post getOnePost(#PathVariable UUID id){
return postService.getOne(id);
}
#RequestMapping(value = "/{id}", method = DELETE)
public void deleteOnePost(#PathVariable UUID id){
postService.deleteOnePost(id);
}
}
My question is how do I fetch all the comments for each individual post, whenever I fetch all the posts?
Sorry, I come from a NoSQL background, so this is a bit daunting at first.
What you need to do is to create a bidirectional #OneToMany association from the Post to Comments:
add a field in Post class
#OneToMany(
mappedBy = "postId",
cascade = CascadeType.ALL
)
private List<Comments> comments = new ArrayList<>();
From now on, when you get Post from the database, Comments will be fetched at the same time.
Working on my spring mvc project I face following issu:
I have UnitAppUser, VStanAppUser and RjuAppUser entity classes which extend User entity. User entity stores some general informations. Rest of inheritant entities stores the references to the particular entities (UnitAppUser has a field Unit type, VStanAppUser has a VStan type so on).
Here is my parent User entity
#Entity
#Inheritance(strategy=InheritanceType.JOINED)
#Table(name="app_user")
public class User implements Serializable {
/**
*
*/
private static final long serialVersionUID = 6628717324563396999L;
#Id #GeneratedValue(strategy=GenerationType.IDENTITY)
private Integer id;
#NotEmpty
#Column(name="SSO_ID", unique=true, nullable=false)
private String ssoId;
#NotEmpty
#Column(name="PASSWORD", nullable=false)
private String password;
#NotEmpty
#Column(name="FIRST_NAME", nullable=false)
private String firstName;
#NotEmpty
#Column(name="LAST_NAME", nullable=false)
private String lastName;
#NotEmpty
#Column(name="EMAIL", nullable=false)
private String email;
}
Here's my child classes:
#Entity
#Table(name = "unit_app_user")
public class UnitAppUser extends User implements Serializable {
#JoinColumn(name = "UNITWORK", referencedColumnName = "ID")
#ManyToOne(optional = false)
private UnitDepart unitdepart;
public UnitDepart getWorkat() {
return unitdepart;
}
public void setWorkat(UnitDepart unitdepart) {
this.unitdepart = unitdepart;
}
}
#Entity
#Table(name="rju_app_user")
public class RjuAppUser extends User implements Serializable{
#JoinColumn(name = "workrju", referencedColumnName = "id")
#ManyToOne(optional = false)
private Rju rju;
public Rju getWorkat() {
return rju;
}
public void setWorkat(Rju rju) {
this.rju = rju;
}
}
and finally my VStan entity:
#Entity
#Table(name="vstan_app_user")
public class VstanAppUser extends User implements Serializable{
#JoinColumn(name = "WORKSTATION", referencedColumnName = "kod")
#ManyToOne(optional = false)
private Vstan vstan;
public Vstan getWorkat() {
return vstan;
}
public void setWorkat(Vstan vstan) {
this.vstan = vstan;
}
}
How to write generic dao and service to get specific entity?
As a result I should have something like this
userService.findBySSOId("somessoId").getWorkat() //should return UnitDepart, Rju or VStan
Post class
one to many mapping
Composite primary key using id
I am getting null pointer exception when I make get request for getting comments
#Entity
#Table(name = "posts")
public class Post {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#NotNull
#Size(max = 100)
#Column(unique = true)
private String title;
#NotNull
#Size(max = 250)
private String description;
#NotNull
#Lob
private String content;
#NotNull
#Temporal(TemporalType.TIMESTAMP)
#Column(name = "posted_at")
private Date postedAt = new Date();
#NotNull
#Temporal(TemporalType.TIMESTAMP)
#Column(name = "last_updated_at")
private Date lastUpdatedAt = new Date();
#OneToMany(cascade = CascadeType.ALL,
fetch = FetchType.LAZY,
mappedBy = "post")
private Set<Comment> comments = new HashSet<>();
public Post() {
}
public Post(String title, String description, String content) {
this.title = title;
this.description = description;
this.content = content;
}
//getters and setters
}
Comment class
many to one mapping with composite primary keys using #Idclass
#Entity
#IdClass(CommentId.class)
#Table(name = "comments")
public class Comment {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#NotNull
#Lob
private String text;
#Id
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "post_id", nullable = false)
private Post post;
public Comment() {
}
public Comment(String text) {
this.text = text;
}
//getters and setters
}
Id class
CommentId
public class CommentId implements Serializable {
private static final long serialVersionUID = 1L;
private Post post;
private Long id;
public CommentId(Post post, Long id) {
super();
this.post = post;
this.id = id;
}
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result+ ((post == null) ? 0 : post.hashCode());
result = prime * result ;
return result;
}
public boolean equals(Object object) {
if (object instanceof CommentId) {
CommentId pk = (CommentId)object;
return id.equals(pk.id) && post == pk.post;
} else {
return false;
}
}
//getters and setters
}
repositories
PostRepository
CommentRepository
#Repository
public interface PostRepository extends JpaRepository<Post, Long> {
}
#Repository
public interface CommentRepository extends JpaRepository<Comment, Long>
{
}
Controller class get request and I am using mysql database
#RestController
#RequestMapping("/demo")
public class Controller {
#Autowired
PostRepository ps;
CommentRepository cs;
#GetMapping("/post")
public List<Post> getAll(){
return ps.findAll();
}
#GetMapping("/comment")
public List<Comment> getAllcom(){
return cs.findAll();
}
}
Database Tables
post
tag
ref_post_tag
post and tag has a Many-to-Many relationship
Entities
Post
#Entity
#Table(name = "post")
public class Post implements Serializable{
private static final long serialVersionUID = 1783734013146305964L;
public enum Status {
DRAFT, REMOVED, LIVE;
}
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.AUTO)
private String id;
#Column(name = "title")
private String title;
#Column(name = "create_time")
private LocalDateTime createTime;
#Column(name = "update_time")
private LocalDateTime updateTime;
#Column(name = "content")
private String content;
#Column(name = "status")
#Enumerated(EnumType.STRING)
private Status status;
#ManyToMany
#JoinTable(
name = "ref_post_tag",
joinColumns = #JoinColumn(name="post_id",referencedColumnName = "id"), inverseJoinColumns = #JoinColumn(name="tag_id", referencedColumnName = "id"))
private List<Tag> tagList;
...
}
Tag
#Entity
#Table(name="tag")
public class Tag implements Serializable{
private static final long serialVersionUID = -7015657012681544984L;
#Id
#Column(name="id")
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
#Column(name="name")
private String name;
#Column(name="description")
private String description;
#ManyToMany(mappedBy = "tagList")
private List<Post> postList;
public Integer getId() {
return id;
}
...
}
Tag Repo
public interface TagRepo extends CrudRepository<Tag, Integer>{
}
service implementation
#Service
public class TagServiceImpl implements TagService{
#Autowired
private TagRepo tagRepo;
#Override
public void addTag(Tag tag) {
tagRepo.save(tag);
}
#Override
public Tag getTag(Integer id) {
Tag tag = tagRepo.findOne(id);
return tag;
}
#Override
public List<Tag> findAllTags() {
return CollectionUtil.toArrayList(tagRepo.findAll());
}
}
sample test (Updated)
#RunWith(SpringJUnit4ClassRunner.class)
#SpringApplicationConfiguration(classes = TestContextConfiguration.class)
#Transactional
public abstract class ServiceTest {
}
public class TagServiceTest extends ServiceTest{
#Autowired
private TagService tagService;
#Autowired
private TagRepo tagRepo;
#Test
#Transactional
public void addTag() throws Exception {
Tag tag = new Tag();
tag.setName("new tag");
tag.setDescription("this is a new tag");
tagService.addTag(tag);
Tag tagCreated = tagRepo.findOne(tag.getId());
assertNotNull(tagCreated);
assertEquals(tagCreated.getName(), tag.getName());
}
#Test
public void getTag() throws Exception {
Tag tag = tagService.getTag(1); // tag "java" has an ID of "1"
assertNotNull(tag);
assertEquals(tag.getName(), "java");
assertEquals(143,tag.getPostList().size()); // 143 posts under tag "java"
}
}
Question
The sample test case passes. It means that the postList in fetched Tag is also eagerly fetched and filled.
Is Spring data repository's methods eagerly fetching by default?
If yes, what is the best way to change this to lazy fetching?