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 ...
}
Related
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;
}
I have a simple object which I want save in DB. But for time it was necessary to change someone parameters. I drop my old table but when I turn on my program - Hibernate still create DB with old columns.
For example:
My old class looked like this :
#Entity
#Table(name = "Tests")
public class Test {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
private String description;
private boolean isFree;
private int status;
private String author;
private String section;
#OneToMany(mappedBy = "qTest", fetch = FetchType.LAZY, cascade = { CascadeType.ALL })
private List<Question> questions;
private String commentToAdmin;
...
and geters-seters
}
In table I have column "status" like INT.
But then I change this class parameter to String. Now my class looks like this:
#Entity
#Table(name = "Tests")
public class Test {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
private String description;
private boolean isFree;
#Column(name = "statusT")
private String status;
private String author;
private String section;
#OneToMany(mappedBy = "qTest", fetch = FetchType.LAZY, cascade = { CascadeType.ALL })
private List<Question> questions;
private String commentToAdmin;
And geters-setters
}
But after drop old table and restart my application column "status" still "INT" and his name "status" (not "statust").
Please help me understand why it's happening
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'm creating a MySQL database as followed :
database design
the Country and Province tables are pre-filled with data. I have the application running and can get stuff no problem, and also the join table person_has_address works when getting.
however, when I insert data using post I want to be able to set the ID of the province, and let spring data jpa just add that number to add_pro_id in the Address table. For example, when I post the following json:
{ "firstName":"bilbo", "lastName":"baggings", "address":{"street":"streetName", "streetNum":3, "zipcode":"1337GG", "city":"TheCity", "province":{"name":"aProvinceName"}} }
jpa should see that aProvinceName exists and grab that id and add that to add_pro_id.
Now it just insert aProvinceName as new value in province and add the new id to add_pro_id.
The person class:
#Entity
public class Person {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="per_id")
private int id;
#Column(name="per_name")
private String firstName;
#Column(name="per_surname")
private String lastName;
#Column(name="per_birth_date")
private String birthDate;
#Column(name="per_fax")
private String fax;
#Column(name="per_phone")
private String phone;
#Column(name="per_email")
private String email;
#OneToOne(optional = false, cascade = CascadeType.ALL)
#JoinTable(name="person_has_address", joinColumns = {#JoinColumn(name="pha_per_id", referencedColumnName = "per_id")}, inverseJoinColumns = {#JoinColumn(name="pha_add_id", referencedColumnName = "add_id")})
private Address address;
// getters and setters
This is the person repository:
#RepositoryRestResource(collectionResourceRel = "people", path = "people")
public interface PersonRepository extends PagingAndSortingRepository<Person, Long> {
List<Person> findByLastName(#Param("name") String name);
}
This is the address class:
#Entity
public class Address {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="add_id")
private int id;
#Column(name = "add_street")
private String street;
#Column(name="add_street_num")
private int streetNum;
#Column(name="add_zip")
private String zipcode;
#Column(name="add_city")
private String city;
#JoinColumn(name="add_pro_id", referencedColumnName = "pro_id")
#ManyToOne(optional=false, cascade = CascadeType.ALL)
private Province province;
// getters and setters
Province class:
#Entity
public class Province {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="pro_id")
private int id;
#Column(name="pro_name")
private String name;
#ManyToOne
#JoinColumn(name="pro_cou_id")
private Country country;
// getters and setters
And lastly country class:
#Entity
public class Country {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="cou_id", insertable = false, updatable = false)
private int id;
#Column(name="cou_name", insertable = false, updatable = false)
private String name;
// getters and setters
I've tried adding insertable = false and updatable = false, but the application then just inserts NULL values in my database. I've also tried working with #primarykeyjoins, but to no success.
if anyone knows how I should tackle this problem I would much appreciate it!
Thanks in advance.
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;