In a spring mvc app using hibernate over MySQL, I am encountering problems when I try to create polymorphic subclasses that inherit their id from a BaseEntity. You can see my intended use when you read my AccessLog class below, which has properties of type BaseEntity. The actor_entity and target_entity properties should each be fillable with a variety of different types of entities, such as User, OutsideSystem, Document, etc., each of which inherit from BaseEntity.
How do I set this up in code?
Here is my current java:
#Entity
#Inheritance(strategy = InheritanceType.JOINED)
public class BaseEntity {
#Id
#GeneratedValue(strategy = GenerationType.TABLE)
protected Integer id;
//other stuff
}
#Entity
#Table(name="users")
public class User extends BaseEntity{
//other stuff
}
#Entity
#Table(name = "accesslogs")
public class AccessLog extends BaseEntity{
#ManyToOne
#JoinColumn(name = "actorentity_id")
private BaseEntity actor_entity;
#ManyToOne
#JoinColumn(name = "targetentity_id")
private BaseEntity target_entity;
#Column(name="action_code")
private String action;
}
Here is my current DDL:
CREATE TABLE IF NOT EXISTS baseentity(
id int(11) UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY
)engine=InnoDB;SHOW WARNINGS;
CREATE TABLE IF NOT EXISTS accesslogs(
id int(11) UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
actorentity_id int(11) UNSIGNED NOT NULL,
targetentity_id int(11) UNSIGNED NOT NULL,
action_code varchar(100),
access_date DATETIME
)engine=InnoDB;SHOW WARNINGS;
CREATE TABLE roles (
id int(11) UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
role varchar(20) NOT NULL
) ENGINE=InnoDB;
CREATE TABLE users (
id int(11) UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
login varchar(20) NOT NULL,
password varchar(20) NOT NULL
) ENGINE=InnoDB;
CREATE TABLE user_roles (
user_id int(11) UNSIGNED NOT NULL,
role_id int(11) UNSIGNED NOT NULL,
KEY user (user_id),
KEY role (role_id)
) ENGINE=InnoDB;
Why do you need BaseEntity annotate with Entity? You don't need to specify #Inheritance(strategy = InheritanceType.JOINED). BaseEntity should have #MappedSuperclass annotation
And you don't need to create baseentity table
Related
I'm new to JPA and trying to understand if there's a way to make an Entity where one column is coming from another table that is linked by a foreign key. For example, consider the following tables:
CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`email` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
);
CREATE TABLE `jobs` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11),
PRIMARY KEY (`id`),
CONSTRAINT `fk_jobs_users` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`)
);
Now I want to make an Entity for the "jobs" table that will include the user.email. I know I can do something like
#Entity
#Table(name = "jobs")
public class JobEntity {
#Id
#Column(name = "id")
private Long id;
#Column(name = "user_id")
private Long userId;
#Formula("(select user.email FROM user WHERE user.id = user_id)")
private String userEmail;
But I feel there's a way I can better leverage the foreign key relationship, but I'm not sure how. I was looking into #JoinColumn but was not seeing the result I wanted since the foreign key is a different column in my Entity. Is there a better way rather than using #Forula to do this?
I don't really understand this. I'm sure #JoinColumn can accomplish the behavior you're looking for.
I was looking into #JoinColumn but was not seeing the result I wanted since the foreign key is a different column in my Entity
Example:
#Entity
#Table(name = "jobs")
public class KronosFileEntity {
#Id
#Column(name = "id")
private Long id;
#ManyToOne
#JoinColumn(name = "user_id", referencedColumn = "id")
private User user;
}
Then you can access the email like job.getUser().getEmail()
Or add a convenience method if that helps
public String getUserEmail() {
return user.getEmail();
}
Then
job.getUserEmail()
In my db I have two tables which look like this:
CREATE TABLE IF NOT EXISTS `Lokal` (
`idLokal` int(11) NOT NULL AUTO_INCREMENT,
`Ocena_idOcena` int(11) NOT NULL,
PRIMARY KEY (`idLokal`,`Ocena_idOcena`),
KEY `fk_Lokal_Ocena_idx` (`Ocena_idOcena`)
)
CREATE TABLE IF NOT EXISTS `Ocena` (
`idOcena` int(11) NOT NULL AUTO_INCREMENT,
`Ocena` int(1) DEFAULT NULL,
PRIMARY KEY (`idOcena`)
)
I want to map my Lokal entity to this Ocena table using #SecondaryTable Hibernate annotation, what I managed to achieve is this:
#Entity
#Table(name="Lokal")
#SecondaryTable(name = "Ocena", pkJoinColumns=#PrimaryKeyJoinColumn(name="Ocena_idOcena"))
public class Lokal {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="idLokal")
private int id;
#Column(table="Ocena" ,name="idOcena")
private int rating;
//--Getters and Setters skipped--//
}
But all I get is an error saying:
ERROR: Unknown column 'this_1_.Ocena_idOcena' in 'on clause'
I think I'm misunderstanding the #SecondaryTable annotation, but this is my first Spring/Hibernate application so I'd be glad for any kind of help.
Try this:
#Entity
#Table(name="Lokal")
#SecondaryTable(name = "Ocena", pkJoinColumns=#PrimaryKeyJoinColumn(name="idOcena"))
public class Lokal {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="idLokal")
private int id;
#Column(table="Ocena" ,name="rating")
private int rating;
//--Getters and Setters skipped--//
}
I'm trying to find relevant JPA documentation, but having trouble finding anything that specifies if I am allowed to make an ElementCollection of an Entity. I know the typical use is to make an #ElementCollection of #Embeddable, but due to a Hibernate bug I encountered, I need to make my embeddable class into its own entity.
I would like to maintain the entity's lifecycle to be controlled by the parent class. Consequently, I am hoping not to create any DAO/Repository for the new entity.
Although Hibernate allows this to occur (it properly generates the DDL), I have not actually tested persistence of the parent entity yet.
Additionally, I have not been able to find any way to specify the join column mapping to the new entity.
For example, given:
public class User {
#TableGenerator( name="UUIDGenerator", pkColumnValue="user_id", table="uuid_generator", allocationSize=1)
#Id
#GeneratedValue(strategy = GenerationType.TABLE, generator="UUIDGenerator")
#Column(name = "id")
private Long id;
/**
* Address
*/
#Valid
#ElementCollection(fetch=FetchType.LAZY)
#CollectionTable(name="user_address", joinColumns=#JoinColumn(name = "user_id", referencedColumnName = "id"))
#OrderColumn
private List<Address> address;
}
and
#Entity
public class Address {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private Long id;
/**
* Multiple street lines allowable
*/
#NotBlank
#ElementCollection(targetClass=String.class, fetch=FetchType.LAZY)
#CollectionTable( joinColumns=#JoinColumn(name = "address_id", referencedColumnName = "id"))
#OrderColumn
private List<String> street;
}
it generates the following MySQL tables:
CREATE TABLE `user` (
`id` bigint(20) NOT NULL,
PRIMARY KEY (`id`),
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `user_address` (
`user_id` bigint(20) NOT NULL,
`address` bigint(20) NOT NULL,
`address_order` int(11) NOT NULL,
PRIMARY KEY (`user_id`,`address_order`),
UNIQUE KEY `UK_m09f5sbmw3q9drll2qig9i07q` (`address`),
KEY `FK_m09f5sbmw3q9drll2qig9i07q` (`address`),
KEY `FK_kfu0161nvirkey6fwd6orucv7` (`user_id`),
CONSTRAINT `FK_kfu0161nvirkey6fwd6orucv7` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`),
CONSTRAINT `FK_m09f5sbmw3q9drll2qig9i07q` FOREIGN KEY (`address`) REFERENCES `address` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `address` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `address_street` (
`address_id` bigint(20) NOT NULL,
`street` varchar(255) DEFAULT NULL,
`street_order` int(11) NOT NULL,
PRIMARY KEY (`address_id`,`street_order`),
KEY `FK_jrcnrclixxqroefuqc7gjhoh` (`address_id`),
CONSTRAINT `FK_jrcnrclixxqroefuqc7gjhoh` FOREIGN KEY (`address_id`) REFERENCES `address` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
I'd like to find a way to change the field name for user_address.address. So far, the only way I can figure out how to do this is to make it a #OneToMany mapping and use a #JoinTable() definition. Is there no way from within #ElementCollection?
You cannot have an ElementCollection containing Entities, these are mutually exclusive concepts in JPA.
You can try a one-to-many or many-to-many depending on your needs. If you set fetching to eager and cascade all it should be fine.
I'm trying to run a simple example which is just a mapping with a table and to print all the values stored in it.
I'm getting all my fields well except my id.
Here is my table when i do an export on it
CREATE TABLE `adress` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`streetNumber` tinyint(4) DEFAULT NULL,
`street` varchar(45) DEFAULT NULL,
`city` varchar(45) DEFAULT NULL,
`zipCode` int(11) DEFAULT NULL,
`state` varchar(45) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1;
LOCK TABLES `adress` WRITE;
INSERT INTO `adress` VALUES (1,12,'Canada street','LOS ANGELES',441233,'California'),(2,54,'5th avenue','NEW YORK CITY',884769,'New York');
UNLOCK TABLES;
My Entity class :
#Entity
#Table(name = "adress")
#XmlRootElement
public class Adress implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#Column(name = "id")
private Integer id;
#Column(name = "streetNumber")
private Short streetNumber;
...
If i do a "findAll()" i'm able to get all my datas from the db.
But the id is null, all the other fields have their values
I have tried several stuff but i'm not going everywhere.
If someone can see where or about what is my mistake i'll appreciate a lot your help.
Thanks in advance
I have 2 tables:
CREATE TABLE `addr1` (
`id` int(11) DEFAULT NULL,
`addr2` varchar(20) DEFAULT NULL
) ENGINE=InnoDB;
CREATE TABLE `address` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`address` varchar(250) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB;
primary key of addr1 is set from address table. I created my entities using joined inheritance as
#Entity
#Table(name="addr1")
public class Addr1 extends Address {
#Column(name="addr2")
private String addr2;
// getters and setters follows
}
#Entity
#Table(name = "address")
#Inheritance(strategy=InheritanceType.JOINED)
public class Address implements Serializable {
#Id
#GeneratedValue
#Column(name = "id")
private int id;
#Column(name = "address", nullable = false, length = 250, insertable = true)
private String address;
// getters and setters follows
}
Now I have a row in address table with id 2. I want to inset a row in addr1 table with same id (2). I had tried
Address addr = em.getReference(Address.class, new Integer(4));
Addr1 addr1 = new Addr1(addr);
addr1.setAddr2("dsdsd");
em.persist(addr1);
but I am getting an error
javax.persistence.PersistenceException:
org.hibernate.PersistentObjectException: detached entity passed to
persist: Addr1
Please help me.
Regards,
Praveen
It's impossible. Inheritance implies a is-a relationship. Your entity instances can thus be either a bare Address, or an Addr1. And a Java object can't change its type. You can't take an object of type Object, and ask the JVM to change its type and make it an object of type String instead. It's the same here.
If you need to do that, then you should use composition, not inheritance: an Address can have an Addr1. And you should thus have a OneToOne association beteween Address and Addr1, instead of an inheritance relationship.