I have 2 tables:
#Entity
#Table
public class ProductEntity extends AbstractEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long productId;
#OneToMany(mappedBy = "product", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
private Set<ProductItemEntity> productItems;
}
#Entity
#Table
public class ProductItemEntity extends AbstractEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long itemId;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "PRODUCT_ID", nullable = false)
private ProductEntity product;
#Column(name="PRODUCT_RATE") // Unique
private Integer productRate;
}
I am trying to run a test where I am querying by productId and productRate, which is as follow:
#Query("SELECT p FROM ProductEntity p JOIN FETCH p.productItems pi WHERE p.productId = :productId AND pi.productRate = :rate ")
ProductEntity findByProductAndRate(#Param("productId") Long productId, #Param("rate") Integer rate);
I save a product and product item first. Then execute above method to get the product with product item. But I get null result.
Don't know if I am missing something. Any help would be appreciated.
Spring Boot
H2 (#DataJpaTest)
Related
I'm using Spring JPA and MySQL as the database. I have trouble with self-referencing its own entity.
I know the code below would do self-referencing, but it actually creates a new table to do so.
#Getter
#Entity
#NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Member extends BaseTimeEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "member_id")
private Long id;
#ManyToMany
#JoinColumn(name = "followings_id")
private List<Member> followings = new ArrayList<Member>();
#ManyToMany
#JoinColumn(name = "followers_id")
private List<Member> followers = new ArrayList<Member>();
#ManyToMany
#JoinColumn(name = "blocked_id")
private List<Member> blocked = new ArrayList<Member>();
...
}
Question: I'm wondering if I can do this in a single table(which would be the member table) without creating a new table to do many-to-many self-referencing.
It is possible,
Instead of using the #ManyToMany annotation, you can use the #OneToMany and #ManyToOne annotations to create the self-referencing relationship
#Getter
#Entity
#NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Member extends BaseTimeEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "member_id")
private Long id;
#OneToMany(mappedBy = "follower")
private List<Follow> followings = new ArrayList<>();
#OneToMany(mappedBy = "following")
private List<Follow> followers = new ArrayList<>();
#OneToMany(mappedBy = "blocker")
private List<Block> blocked = new ArrayList<>();
}
#Entity
#Getter
#NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Follow {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne
#JoinColumn(name = "follower_id")
private Member follower;
#ManyToOne
#JoinColumn(name = "following_id")
private Member following;
}
#Entity
#Getter
#NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Block {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne
#JoinColumn(name = "blocker_id")
private Member blocker;
#ManyToOne
#JoinColumn(name = "blocked_id")
private Member blocked;
}
Now Follow and Block entities represent the many-to-many relationships between Member entities and follower and following properties in the Follow entity represent the two sides of the many-to-many relationship, and the same is for blocked and blocker.
I have two table user(id,name) and user_mails(id,email,user_id) user to user_mails have one to many relation.
I have created following entity in spring boot
User
#Entity
#Table(name = "user")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private int id;
#Column(name = "name", nullable = false)
private String name;
#OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
private Set<UserMail> userMails =new HashSet<UserMail>(0);
//Getter setter and constructor
}
UserMail
#Entity
#Table(name = "user_mails")
public class UserMail {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#Column(name = "email", nullable = false)
private String name;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "user_id")
private User user;
It is showing following output on calling controller
[{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":
and more
I want to access all users with all mail ids also want to acces mail id with user details
What changes should I do to get proper result
I have a class called Tag:
#Entity
#Table(name = "tags")
public class Tag {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
},
mappedBy = "tags")
private Set<Post> posts = new HashSet<>();
...
}
And a class called Post
#Entity
#Table(name = "posts")
public class Post {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
})
#JoinTable(name = "post_tags",
joinColumns = { #JoinColumn(name = "post_id") },
inverseJoinColumns = { #JoinColumn(name = "tag_id") })
private Set<Tag> tags = new HashSet<>();
...
}
It creates another table named post_tags.
How can I write a Controller to access that table as it is not similar a repository?
Is there more easy and convenient way to implement ManyToMany relationship ?
My pom.xml
You don't need to access that relation table manually. You can load load all Tag entities, and then load all the referenced Post entities.
The relation table is enterily managed by your ORM frameork.
But, if you still want to access the relation table, you can use native queries in your Spring Data JPA repository, e.g.
#Query(value="select post_id, tag_id from post_tags", nativeQuery=true)
List<PostTag> loadPostTags();
PostTag class is not a jpa-managed entity and must match the structue of the returned table:
public class PostTag {
private long postId;
private long tagId;
// getter, setter
}
Use this way
#Entity
#Table(name = "tags")
public class Tag {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
#ManyToMany(cascade = CascadeType.ALL)
#JoinTable(name = "post_tags",
joinColumns = { #JoinColumn(name = "id") },
inverseJoinColumns = { #JoinColumn(name = "post_id") })
private Set<Post> posts = new HashSet<>();
...
}
#Entity
#Table(name = "posts")
public class Post {
#Id
#Column(name = "post_id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long postId;
...
}
I have three tables:
1) book: id (primary), name
2) shop: code (unique, not primary), name
3) book_shop: book_id, shop_id (code), price
I want to get shops in book like
book.getShop();
How to link this entities?
I tried:
#Data
#NoArgsConstructor
#Entity
#Table(name = "book", schema = "example")
#EntityListeners(AuditingEntityListener.class)
public class Book {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
#OneToMany(mappedBy = "book", cascade = CascadeType.ALL, orphanRemoval = true)
private Set<BookShop> bookShop;
}
.
#Data
#NoArgsConstructor
#Entity
#Table(name = "shop", schema = "example")
#EntityListeners(AuditingEntityListener.class)
public class Shop {
#Id
private int code;
private String name;
#OneToMany(mappedBy = "shop", cascade = CascadeType.ALL, orphanRemoval = true)
private Set<BookShop> bookShop;
}
.
#Data
#NoArgsConstructor
#Entity
#Table(name = "book_shop", schema = "example")
public class BookShop implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Id
#ManyToOne
#JoinColumn(name = "book_id")
private Book book;
#Id
#ManyToOne
#JoinColumn(name = "shop_id")
private Shop shop;
#Column(name = "price")
private int fromDate;
}
This code return empty set: Book book = bookRepostiory.getById(1).get().getBookShop()
Try the many to many mapping implement like as below remove your book_shop table,
add this code to shop entity,
#ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.PERSIST)
#JoinTable(name = "book_shop",
joinColumns = {#JoinColumn(name = "book_id", nullable = false)},
inverseJoinColumns = {#JoinColumn(name = "shop_id", nullable = false)})
private Set<Book> bookList = null;
add this code to book entity,
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL,
mappedBy ="bookList")
private Set<Shop> shopList=null;
if any issue inform!!
I would suggest, first - initialize the set in the entity
private Set<BookShop> bookShop = new HashSet<>();
Second, add fetch = FetchType.EAGER to your association, for e.g.
#OneToMany(fetch = FetchType.EAGER, mappedBy = "book", cascade = CascadeType.ALL)
I have an unidirectional OneToMany JPA entity mapping in my (Spring Framework + Spring Data + Hibernate JPA) project. Entity classes are like in the following code.(I have removed irrelevant class members for brevity).
#Entity
#Table(name = "employees")
class Employee{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Integer id;
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
#JoinColumn(name = "employee_id")
private List<DepartmentAssignment> departmentAssignments = new ArrayList<>();
}
#Entity
#Table(name = "department_assignments")
class DepartmentAssignment{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Integer id;
#NotNull
#Column(name = "employee_id")
private Integer employeeId;
#NotNull
#Column(name = "department_id")
private Integer departmentId;
}
#Entity
#Table(name = "departments")
class Department{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Integer id;
}
And, in one of my service classes have a method to remove a DepartmentAssignment from an Employee like below.
public Employee deleteDepartmentAssignment(Integer empId, Integer deptAssignmentId) {
Employee employee = employeeRepository.findOne(empId);
if(employee != null) {
for ( DepartmentAssignment da : employee.getDepartmentAssignments()) {
if(da.getId().equals(deptAssignmentId)) {
employee.getDepartmentAssignments().remove(da);
employee = employeeRepository.save(employee);
break;
}
}
}
return employee;
}
However, calling above methods gives me an error: org.hibernate.exception.ConstraintViolationException ,and in the SQL log, I can see Column 'employee_id' cannot be null error for the last SQL statement of the transaction.
Can anybody tell me what I'm doing wrong here and how to get it fixed?
You don't need to add
#NotNull
#Column(name = "employee_id")
private Integer employeeId;
to the Employee, if you use #JoinColumn(name = "employee_id"). Try to remove it.
You can try the following, not sure why you use the plain id in the object. Thats not object relational mapping.
For more details see Hibernate triggering constraint violations using orphanRemoval
#Entity
#Table(name = "employees")
class Employee{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "employee", orphanRemoval = true)
private List<DepartmentAssignment> departmentAssignments = new ArrayList<>();
}
#Entity
#Table(name = "department_assignments")
class DepartmentAssignment{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#ManyToOne(optional=false)
private Employee employee;
#ManyToOne(optional=false)
private Department department;
}
#Entity
#Table(name = "departments")
class Department{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
}
You must look .hbm.xml file and you should mapping your Entity in this file and
you can look this example
http://www.mkyong.com/hibernate/hibernate-one-to-many-relationship-example/
I hope it will be useful for you.
try removing
cascade = CascadeType.ALL
but im not 100% sure..