I've got following two tables:
Customer
id
name
Order
id
product_name
customer_id
with a 1 to 1 relation
and java entities:
#Data
public class Customer{
#Id
private Long id;
private String name;
}
#Data
public class Order{
#Id
private Long id;
#Column("id")
private Customer customer; //i want to somehow map this
private String productName;
}
and a controller
#Controller
public class MyController{
//...
#GetMapping("/")
public String getmap(Model m){
System.out.println(repository.findAll()) //prints "nullrows" due to wrong sql statement
return "mytemplate";
}
}
my current issue is, that spring is executing following sql statement:
SELECT Order.id, Order.product_name, Customer.id, Customer.name
FROM Order LEFT OUTER JOIN Customer ON Customer.id = Order.id
what i actually want is to join on Customer.id = Order.customer_id while leaving the classes as they are i.e. the customer reference needs to stay in order.
i've tried every annotation that i could find so far and have made no progress.
EDIT:
I am not allowed to use jpa/hibernate
One workaround is to do the following:
#Data
public class Customer{
#Id
private Long id;
private String name;
}
#Data
public class Order{
#Id
private Long customerId;
private Long id;
#Column("id")
private Customer customer; //i want to somehow map this
private String productName;
}
causing this to automatically join on Customer.id = Order.customer_id
This does not look like a good fix however.
You can use #OneToOne and #JoinColumn annotations for your One-to-One relationship:
#Data
public class Customer{
#Id
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "order_id", referencedColumnName = "id")
private Order order;
}
#Data
public class Order{
#Id
#Column(name = "id")
private Long id;
#Column(name = "product_name")
private String productName;
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "customer_id", referencedColumnName = "id")
private Customer customer;
}
Related
I am doing an application where I need 2 entities: User and Car.
public class User{
private long id;
private String name;
}
public class Car{
private long id;
private User firstUser;
private User secondUser;
}
So my table cars_info info will contain
RENT(date), FIRST_USER(id), SECOND_USER(id)
How do I connect this using hibernate? I need unidirectional relation. I tried OneToOne, ManyToOne but neither of that works.
Check that you're properly naming the column on your CAR table vs the reference column on the USER table. Example below:
#Entity
#Table(name = "USER")
public class User {
#Id
#Column(name = "USER_ID")
private long id;
#Column(name = "NAME")
private String name;
}
#Entity
#Table(name = "CAR")
public class Car {
#Id
#Column(name = "CAR_ID")
private long id;
#ManyToOne
#JoinColumn(name = "FIRST_USER_ID", referencedColumnName = "USER_ID")
private User firstUser;
#ManyToOne
#JoinColumn(name = "SECOND_USER_ID", referencedColumnName = "USER_ID")
private User secondUser;
}
I am trying some hibernate.The following is the pojo I am using,
#Entity
#Table(name = "person")
public class Person {
#Id
#GeneratedValue
#Column(name = "person_id")
private long person_id;
#Column(name = "name")
private String name;
#Column(name = "Address")
private String Address;
#OneToMany(fetch = FetchType.EAGER, mappedBy = "person" )
private Set<Phone> phone;
//Getters ande Setters
}
#Entity
#Table(name = "phone")
public class Phone{
#Id
#GeneratedValue
#Column(name = "phone_id")
private long phone_id;
#Column(name = "name")
private String name;
#ManyToOne(cascade = CascadeType.MERGE,fetch = FetchType.EAGER)
#JoinColumn(name = "person_id")
private Person person ;
//Getters ande Setters
}
What I want is when I fetch a record from person and need corresponding all phone details. (Like Select * from person) I have around 1360 data in person and nearly double in phone. But for some reason error is thrown. I am not able to see full error stack . Below is the error I am getting.
at
com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:505)
~[jackson-databind-2.4.6.jar:2.4.6] at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:639)
~[jackson-databind-2.4.6.jar:2.4.6] at
com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
~[jackson-databind-2.4.6.jar:2.4.6] at
com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:505)
~[jackson-databind-2.4.6.jar:2.4.6] at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:639)
~[jackson-databind-2.4.6.jar:2.4.6] at
com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
~[jackson-databind-2.4.6.jar:2.4.6] at
com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
~[jackson-databind-2.4.6.jar:2.4.6] at
com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
~[jackson-databind-2.4.6.jar:2.4.6] at
.....
I was not able to post all error that I got
Using JsonManagedReference and JsonBackReference annotations may solve your problem.
While jackson trying to convert objects to json, visits objects and
their attributes. So if objects have bi-directional relations, for
jackson we need to think about cyclic dependencies. Jackson starts
serialize person and see the phone list and take a phone from list and
start serialize phone and sees person in phone and take person from
phone and start serilize it bla bla bla so this is an endless loop. If
jackson sees these annotations, stops and breaks the loop.
Give it a try as below code;
#Entity
#Table(name = "person")
public class Person {
#Id
#GeneratedValue
#Column(name = "person_id")
private long person_id;
#Column(name = "name")
private String name;
#Column(name = "Address")
private String Address;
#JsonManagedReference
#OneToMany(fetch = FetchType.EAGER, mappedBy = "person" )
private Set<Phone> phone;
// Getters and Setters
}
#Entity
#Table(name = "phone")
public class Phone{
#Id
#GeneratedValue
#Column(name = "phone_id")
private long phone_id;
#Column(name = "name")
private String name;
#ManyToOne(cascade = CascadeType.MERGE,fetch = FetchType.EAGER)
#JoinColumn(name = "person_id")
#JsonBackReference
private Person person;
// Getters and Setters
}
You can alternatively use #JsonIdentityInfo on classes
#Entity
#JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="#id")
#Table(name = "phone")
public class Phone {
}
#Entity
#JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="#id")
#Table(name = "person")
public class Person {
}
I was also getting the same error.
Using #JsonBackReference and #JsonManagedReference was still giving me error so I used #JsonIdentityInfo and it worked like a charm.
Below are my classes :-
BookModel :
#Data
#Entity
#Table(name = "book")
#JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="bookId")
public class BookModel implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "book_id")
private int bookId;
#Column(name="book_name")
private String bookName;
#Column(name="book_author")
private String bookAuthor;
#Column(name="book_publish_date")
private Date bookPublishDate;
#Column(name="book_price")
private double bookPrice;
#OneToMany(mappedBy = "book_model")
List<BookImagesModel> bookImagesModels;
//getters and setters
//default constructor
}
BookImagesModel :
#Data
#Entity
#Table(name = "book_images")
#JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="imageId")
public class BookImagesModel implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "image_id")
private long imageId;
#ManyToOne
#JoinColumn(name = "book_id")
private BookModel book_model;
#Column(name = "image_path")
private String imagePath;
//getters and setters
//default constructor
}
I used Mysql8 database with spring boot.
I can't make my foreign keys auto generate using hibernate and jpa with annotations. Everything seems ok, The entries are saved in database. All the date come from one form which, when submited creates an User object with ModelAttribute and then saves it in Database.
Here are my beans. Anything else i should add ?
#Entity
#Table(name="adress")
public class Adress implements Serializable {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="adress_id")
private Integer adressId;
#NotBlank(message="The city must be completed")
#Column(name="city")
#Size(min=5,max=30)
private String city;
#NotBlank(message="The street must be completed")
#Column(name="street")
#Size(min=5,max=30)
private String street;
#NotNull(message="The street number must be completed")
#NumberFormat
#Column(name="street_no")
private Integer streetNo;
#OneToOne
#JoinColumn(name="user_id")
private User user;}
and the other one:
#Entity
#Table(name="users")
public class User implements Serializable {
#Id
#Column(name="user_id")
#GeneratedValue(strategy=GenerationType.AUTO)
private Integer userId;
#NotBlank(message="Username can't be blank")
#Size(min=5,max=30)
#Column(name="username")
private String username;
#NotBlank(message="Password field can't be blank")
#Size(min=5,max=30)
#Column(name="password")
private String password;
#NumberFormat
#NotNull(message="Age field must not be blank")
#Column(name="age")
private Integer age;
#Column(name="message")
#Size(min=0,max=100)
private String message;
#Column(name="date")
#DateTimeFormat(pattern="dd/mm/yyyy")
private Date dateCreated;
#OneToOne(mappedBy="user",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
private Adress adress;
+getters and setters for them
public void save(T entity){
sessionFactory.getCurrentSession().save(entity);
}
If I understand you correctly and you're trying to get Hibernate to set the foreign key on your related record this might help. Try getting rid of mappedBy and instead specify the JoinColumn. This works for me on a one to many:
The order:
#Entity
#Table(name = "`order`")
public class Order implements Serializable {
#Id
#GeneratedValue
private Long id;
// Order columns...
#OneToMany(cascade = CascadeType.ALL)
#JoinColumn(name = "order_id")
private Set<Item> items;
}
The item:
#Entity
#Table(name = "item")
public class Item implements Serializable {
#Id
#GeneratedValue
private Long id;
// Item columns...
#ManyToOne(optional = false)
#JoinColumn(name = "order_id", referencedColumnName = "id", nullable = false)
private Order order;
}
in adress class
#OneToOne(mappedBy="adress")
private User user;
and in user class
#OneToOne(cascade=CascadeType.ALL,fetch=FetchType.EAGER,optional=false)
#PrimaryKeyJoinColumn
private Adress adress;
I want to make a friend system via hibernate, and I need to check user-friend's corresponding time when this user had related to other.
I hope table columns like following code:
table 1:
int id;
String name;
table 2:
int user_id;
int friend_id;
Date startdate;
POJO code:
public class User {
private int id;
private String name;
private Map<User,Date> friends;
}
I think you need nothing more then JPA. Something like this:
#Entity
#Table(name = "users")
public class User implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column
private String name;
#ElementCollection(fetch = FetchType.EAGER)
#CollectionTable(name = "friendship", joinColumns = #JoinColumn(name = "user_id"))
#MapKeyColumn(name = "friend_id")
#Column(name = "start_date")
private Map<Long, Date> friendshipMap;
... getters/setters ...
}
I have the following two classes, one ReqCandAssociation can have many Comments and it is mapped like so. I need to figure out a way that when I delete a ReqCandAssociation it deletes all of its associated comments. Thanks
#Entity
#Table(name = "candidate_jobReq")
public class ReqCandAssociation implements Serializable {
#Id
private Integer candidateId;
#Id
private Integer jobId;
#Column(name = "reqStatus")
private String reqStatus;
#ManyToOne
#PrimaryKeyJoinColumn(name="candidateId", referencedColumnName="id")
private Candidate candidate;
#ManyToOne
#PrimaryKeyJoinColumn(name="jobId", referencedColumnName="id")
private JobReq jobReq;
public ReqCandAssociation(){
}
Second class
#Entity
#Table(name="comment")
public class Comment {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
private Integer id;
#Column(name="commentText")
private String commentText;
#Column(name="commentDate")
private Date commentDate;
#ManyToOne
#PrimaryKeyJoinColumn(name="reqCandAssociationId", referencedColumnName="id")
private ReqCandAssociation reqCandAssociation;
#ManyToOne
#PrimaryKeyJoinColumn(name="userId", referencedColumnName="id")
private User user;
Change this to the following, i'm making it bidirectional mapping.
#Entity
#Table(name = "candidate_jobReq")
public class ReqCandAssociation implements Serializable {
#Id
private Integer candidateId;
#Id
private Integer jobId;
#Column(name = "reqStatus")
private String reqStatus;
#OneToMany(cascade = { CascadeType.ALL }) //this is added here.
#JoinColumn(name ="reqCandAssociationId")
private Set<Comment> comments;
-----
Readup more on the cascade options. All cascade types are all|none|save-update|delete|all-delete-orphan|delete-orphan
The cascade all will delete all the comments associated to this class.