Is it possible that oracle table has a composite primary key oracle sequenceid +createtimestamp but the #Entity class we have just the #id (sequenceid) primary key ? Timestamp we are adding for the purpose of table partitions which we use for purging later. At the time of storing the entity we will add the timestamp value all the time. From the data point of view id alone is primary key for the record in this case. Can I create entity with primary key as id alone?
In this case you have to create composite primary key in # Entity class. You can as per below example
#Entity
#Table(name="RELEASE_PERSON")
#IdClass(ReleasePersonPK.class)
public class ReleasePerson implements Serializable {
#Column(name="ORDER_NO", nullable=false, precision=2)
private Integer orderNo;
#Id
#Column(name="RELEASE_ID", insertable=false,updatable=false)
private long releaseId;
#Id
#Column(name="PERSON_ID", insertable=false,updatable=false)
private long personId;
#ManyToOne
#JoinColumn(name = "PERSON_ID", referencedColumnName = "PERSON_ID")
private Person person;
#ManyToOne
#JoinColumn(name = "RELEASE_ID", referencedColumnName = "ID")
private Release release;
And your Id Class will be look like below
#Embeddable
public class ReleasePersonPK implements Serializable {
/**
*
*/
private static final long serialVersionUID = -6286499269052596345L;
private Person person;
private Release release;
In my example in ReleasePersone table we will have composite primary key from rRelease(ID) and Person (Person_id).
Let me know if you need anything else.
Ｔhe answer is yes. as you said that the id will be unique in the table, it's definitely ok that just put sequenceId as PK in the entity. If you don't use hibernate to create the table or update the columns of table, it doesn't care what actually in the database.
Related
I want to join column without object reference. is that possible?
I want to do foreign key without object reference like that
#Data
#Entity
#Table(name = "HRM_EMPLOYEE_SALARY_INCREMENT")
public class EmployeeSalaryIncrement implements Serializable {
private static final long serialVersionUID = 9132875688068247271L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name="ID")
private Integer id;
#Column(name = "REFERENCE_NO")
private String referenceNo;
#ManyToOne
#JoinColumn(name = "AUTHORITY", referencedColumnName = "id")
private Integer authority;
#ManyToOne
#JoinColumn(name = "PART_TWO_REGISTER_ID")
private Integer partTwoRegisterId;
#Column(name = "PART_TWO_ORDER_NO")
private String partTwoOrderNo;
#Column(name = "REMARKS")
private String remarks;
#Column(name = "HRM_TYPE")
private Integer hrmType;
}
If I found solve this problem, it will helpful for me.
Joining is not needed in this case. If you only need the foreign key value, then simply add the column as a #Column like any other:
#Data
#Entity
#Table(name = "HRM_EMPLOYEE_SALARY_INCREMENT")
public class EmployeeSalaryIncrement implements Serializable {
private static final long serialVersionUID = 9132875688068247271L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name="ID")
private Integer id;
#Column(name = "AUTHORITY")
private Integer authority;
// other fields
// ...
}
No, I don't think that you can join columns between two entities without adding the reference of one to the related entity. You will have to create one entity class corresponding to each of your relational database table and add the reference of one to the other to establish relation.
However, I understand that you may not need all the attributes from your related table based upon your use case, and only wish to select one column from it. You can do that either by only adding required attributes in your joined table entity class (if you are sure you won't need other attributes for that table anywhere else).
Or you can use custom queries using JPQL in your repository class which selects only the required attributes from the tables that you have joined.
I will show you an example of the second way:
//Say, this is your entity class where you wish to join other table to fetch only one attribute from the joined table-
#Entity
#Table(name = "TABLE1", schema = "SCHEMA1")
public class Table1 {
#Id
#Column(name = "ID")
private String id;
#Column(name = "TABLE2_COLUMN")
private String table2Column;
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "TABLE2_COLUMN1")
private Table2 table2; //refrence of the joined table entity object
}
// And this is the joined table entity class
#Entity
#Table(name = "TABLE2", schema = "SCHEMA1")
public class Table2 {
#Id
#Column(name = "ID")
private String id;
#Column(name = "TABLE2_COLUMN1")
private String table2Column1;
#Column(name = "TABLE2_COLUMN2")
private String table2Column2; // The column which we want to select from the joined table
}
In your repository class -
#Repository
public interface Table1Repository extends JpaRepository<Table1, String> {
#Query("SELECT t1 FROM Table1 t1 WHERE t1.id = :id")
public List<Table1> getTable1Rows(#Param("id") String id);
#Query("SELECT t1.table2.table2Column2 FROM Table1 t1 WHERE t1.id = :id")
public String getTable2Column2(#Param("id") String id);
}
Based upon the response from Markus Pscheidt below, I agree when he said there's no need to join the entities if you only need the attribute which is a foreign key. As foreign key is already present as an attribute in your entity (or table) you are working with.
If you need to fetch any other column apart from foreign key, then you may use JPQL to fetch the exact column that you wish to select.
I have read about the use of #MapsId and #PrimaryKeyJoinColumn annotations, which sounds like a great options. I have two tables (UserList and UserInformation) which have a child, parent relationship, respectively; both classes below are abbreviated to just include the relevant columns. UserInformation's primary key value is always null and does not take the value of its parent column.
User Class
#Entity
#Data
#Table(name = "user_list")
public class UserList {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
// List of foreign keys connecting different entities
#OneToOne(mappedBy = "user")
#MapsId("id")
private UserInformation userInfo;
}
UserInformation Class
#Entity
#Data
#Table(name = "user_information")
public class UserInformation implements Serializable {
#Id
private Integer userId;
#OneToOne
private UserList user;
}
I would prefer to not use an intermediary class if possible. I'm not tied to MapsId or even this implementation if there is a better solution.
Thanks!
The question is not very clear to me, but I think you could improve the following in the modeling of the entity:
The #column annotation can only be omitted when the class parameter is called exactly the same as the database column, taking into account the table name nomenclature, could it be that the column is user_id ?, if so the id parameter should be :
#Id
#column(name="USER_ID")
private Integer userId;
In the user entity being id, it will match the DB ID field so the #column annotation is not necessary
I have a postgres database and I am trying to make a simple REST service with Spring Boot. I have a problem with jpa ManytoMany relationship.
Person Entity:
#Entity
#Table(name = "person", schema = "persons")
public class Person implements Serializable {
#Id
#GeneratedValue(strategy= GenerationType.IDENTITY)
private Integer id;
#Column(nullable = false)
private String name;
#Column(nullable = false)
private String email;
#Column
private Integer age;
#ManyToOne
#JoinColumn(name = "country_id", referencedColumnName = "id")
private Country countryOfBirth;
#ManyToMany
#JoinTable(
name="persons_countries_residence",
joinColumns=#JoinColumn(name="person_id", referencedColumnName="id"),
inverseJoinColumns=#JoinColumn(name="country_id", referencedColumnName="id"))
private List<Country> countriesOfResidence;
// getters and setters and to String method overriden
}
Country Entity:
#Entity
#Table(name = "country", schema = "persons")
public class Country implements Serializable {
#Id
#GeneratedValue(strategy= GenerationType.IDENTITY)
private Integer id;
#Column(name = "country_name")
private String name;
#Column(name = "country_code")
private String code;
// getters and setters and to String method overriden
}
The postgres schema is the following:
Person Table:
CREATE TABLE persons.person
(
id serial NOT NULL,
name character varying(50) NOT NULL,
email character varying(40) NOT NULL,
age integer,
country_id serial NOT NULL,
CONSTRAINT id PRIMARY KEY (id),
CONSTRAINT country_id FOREIGN KEY (id)
REFERENCES persons.country (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)
Country table:
CREATE TABLE persons.country
(
id serial NOT NULL,
country_name character varying(45) NOT NULL,
country_code character varying(10) NOT NULL,
CONSTRAINT country_id PRIMARY KEY (id)
)
Join table:
CREATE TABLE persons.persons_countries_residence
(
person_id integer NOT NULL,
country_id integer NOT NULL,
CONSTRAINT person_country_id PRIMARY KEY (person_id, country_id),
CONSTRAINT persons_countries_residence_country_id_fkey FOREIGN KEY (country_id)
REFERENCES persons.country (id) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE NO ACTION,
CONSTRAINT persons_countries_residence_person_id_fkey FOREIGN KEY (person_id)
REFERENCES persons.person (id) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE CASCADE
)
When i make an HTTP method call, I don't get the Countries of residence.
Service code:
#RequestMapping(method = RequestMethod.GET, produces = {MediaType.APPLICATION_JSON_VALUE, MediaType.APPLICATION_XML_VALUE})
public List<Person> getAllPersons() {
retutn jpaPersonRepository.findAll();
}
Any help appreciated.
Maybe, you need to specify a schema name in the join table name:
#JoinTable(
name="persons_countries_residence", schema="persons",
joinColumns=#JoinColumn(name="person_id", referencedColumnName="id"),
inverseJoinColumns=#JoinColumn(name="country_id", referencedColumnName="id"))
Update your Country class code like :
#Entity
#Table(name = "country", schema = "persons")
public class Country implements Serializable {
#Id
#GeneratedValue(strategy= GenerationType.IDENTITY)
private Integer id;
#Column(name = "country_name")
private String name;
#Column(name = "country_code")
private String code;
#ManyToMany(mappedBy = "countriesOfResidence")
private List<Person> persons;
// getters and setters and to String method overriden
}
Although a ManyToMany relationship is always bi-directional on the
database, the object model can choose if it will be mapped in both
directions, and in which direction it will be mapped in. If you choose
to map the relationship in both directions, then one direction must be
defined as the owner and the other must use the mappedBy attribute to
define its mapping. This also avoids having to duplicate the JoinTable
information in both places.
Do you mean that the country list is null? #ManyToMany associations are lazily loaded by default, you need to enable eager-fetching for it to work straight away.
#ManyToMany(fetch = FetchType.EAGER)
The solution is this:
#ManyToMany
#JoinTable(
name="persons_countries_residence", schema = "persons",
joinColumns=#JoinColumn(name="person_id", referencedColumnName="id"),
inverseJoinColumns=#JoinColumn(name="country_id", referencedColumnName="id"))
private List<Country> countriesOfResidence;
The schema had to be specified at the #JoinTable annotation as well.
I have two tables. I want to make between them relationship, but the thing is that the child table connects to an attribute in a parent node, which is not a PK. How can I assign a non-PK field as a FK for a table?
Here are the tables. User Information:
#Entity
#Table(name="user")
public class userinformation implements Serializable {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="USER_ID")
private int uID;
#Column(name="LIB_ID")
private String libID;
//Other attributes
}
Lib Information
#Entity
#Table(name="libinfo")
public class Auth {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name="AUTH_ID")
private int authID;
#Column(name="LIB_ID")
private String lib_ID;
//Other attributes
}
They both should be linked through libID (surely unique). Any idea how to implement it correctly?
Given:
class User {
#Column(name = "lib_id")
private String libID;
}
you must map the Auth entity as:
class Auth {
#JoinColumn(name = "lib_id", referencedColumnName = "lib_id")
#ManyToOne
private User user;
}
Basically, referencedColumnName is used to inform the JPA provider that it should use a column other than the primary key column of the referenced entity (which is used by default with #ManyToOne mappings).
I have following entities, I am in doubt about the design design like should DRIVING_LICENSE table contain foreign key PERSON_ID or PERSON table should have LICENSE_NUMBER as foreign key from DRIVING_LICENSE table?
If PERSON table has LICENSE_NUMBER then PERSON table will be child table and DRIVING_LICENSE will be parent table, so it implies that when a driving license is deleted then the person should be deleted.
On the other way if DRIVING_LICENSE will have a PERSON_ID then in uni directional one to one relationship in hibernate we will not be able to have a reference of DrivingLicense instead we will have a reference of Person in DrivingLicense, but most of the time it requires that we access Person not DrivingLicense.
Above two are my main doubts? What is the correct choice and what are its pros and cons?
DrivingLicense.java
#Entity
#Table(name = "DRIVING_LICENSE")
public class DrivingLicense {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "LICENSE_NUMBER")
private int licenseNumber;
#Column(name = "DATE_OF_ISSUE")
private Date dateOfIssue;
#OneToOne
#JoinColumn(name = "PERSON_ID")
private Person person;
}
and
Person.java
#Entity
#Table(name = "PERSON")
public class Person {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "PERSON_ID")
private int personId;
#Column(name = "PERSON_NAME", nullable = false, length = 30)
private String personName;
#OneToOne(mappedBy = "person", cascade = CascadeType.ALL)
private DrivingLicense drivingLicense;
}
Drivers License should contain a NOT NULL foreign key to person with a unique constraint and here's why:
Every License must be associated with a person.
A person may have zero or one license associated with them.
Since the license must be associated with a person but a person does not need to have a license, the foreign key should be held by the license table.
The unique constraint on the foreign key will enforce the one-to-one relationship. Without it you'd have a one-to-many relationship.