I'm trying to build a multi-language database, so I've used this database design as a approach for mine.
Now I've two problems/questions:
I want to retrieve all LocalizedEvent for a given language and given categoryId. How can I make a inner join over the LocalizedCategory table with Hibernate Criteria API?
With SQL I would make this statement to get all LocalizedEvent + LocalizedCategory:
SELECT * FROM event e
INNER JOIN
localized_event le ON (le.event_id = e.event_id)
INNER JOIN
localized_category lc ON (lc.category_id = e.category_id)
WHERE
le.locale = 'de' AND lc.locale = 'de'
My current approach looks like this without getting the LocalizedCategory (with Criteria API):
Criteria c = session.createCriteria(LocalizedEvent.class, "localizedEvent");
c.createAlias("localizedEvent.event", "event");
c.createAlias("event.category", "category");
c.add(Restrictions.eq("category.categoryId", categoryId));
c.add(Restrictions.eq("localizedEvent.locale", language));
I think my mapping is not 100% correct. The entity LocalizedEvent should have a property localizedCategory, but I don't want to save the ID of this localizedCategory (therefore I'm using the #Transient annotation) in the LocalizedEvent table, e.g. using a ManyToOne relation (joining LOC_CATEGORY_ID). But I think it's not possible to do this, isn't it? I would have to map this transient field to LocalizedEvent "manually", because Hibernate is not supporting this mapping (if I'm right).
(Using JDBC this property/mapping would cause no problems, because I can easily make my inner joins and assign the property localizedCategory to the LocalizedEvent in a RowMapper or so).
My entities looks like this:
Event
#Entity
#Table(name = "EVENT")
public class Event {
#Id
#GeneratedValue
#Column(name = "EVENT_ID", unique = true)
private Long eventId;
#Column(name = "DATE")
private Date date;
#OneToMany(mappedBy = "event")
private Set<LocalizedEvent> localizedEvents;
#ManyToOne
#JoinColumn(name = "CATEGORY_ID")
private Category category;
}
LocalizedEvent
#Entity
#Table(name = "LOCALIZED_EVENT")
public class LocalizedEvent {
#Id
#GeneratedValue
#Column(name = "LOC_EVENT_ID")
private Long locEventId;
#ManyToOne
#JoinColumn(name = "EVENT_ID")
private Event event;
#Transient
private LocalizedCategory localizedCategory;
#Column(name = "DESCRIPTION")
private String description;
#Column(name = "LOCALE")
private String locale;
}
Category
#Entity
#Table(name = "CATEGORY")
public class Category {
#Id
#GeneratedValue
#Column(name = "CATEGORY_ID", unique = true)
private Long categoryId;
#OneToMany(mappedBy = "category")
private Set<LocalizedCategory> localizedCategories;
#OneToMany(mappedBy = "category")
private Set<Event> events;
}
LocalizedCategory
#Entity
#Table(name = "LOCALIZED_CATEGORY")
public class LocalizedCategory {
#Id
#GeneratedValue
#Column(name = "LOC_CATEGORY_ID")
private Long locCategoryId;
#ManyToOne
#JoinColumn(name = "CATEGORY_ID")
private Category category;
#Column(name = "NAME")
private String name;
#Column(name = "LOCALE")
private String locale;
}
Related
I would like to use the Foreign key "MODEL_ID" to retrieve just one column "MODEL_NAME" from the TT_CARS table,
I tried the following code, that works but it returns the whole CARS object.
#JoinColumn(name = "MODEL_ID", referencedColumnName = "ID")
#ManyToOne(fetch = FetchType.EAGER)
private CARS cars;
Also I tried the code below, its also not working
#SecondaryTable(name = "TT_CARS", pkJoinColumns = #PrimaryKeyJoinColumn(name = "ID", referencedColumnName="MODEL_ID"))
Is there other way to retieve just the column (MODEL_NAME) using hibernate and JPA??
remarks: The modelName should be part of the Options class.
my code
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
#Entity
#Table(name = "TT_OPTIONS")
public class Options {
#Id
#Column(name = "ID")
private String id;
#NotNull
#Column(name = "DESCRIPTION", nullable = false)
private String description;
#Column(name = "MODEL_ID") // Foreign key
private Long modelId;
#Column(name = "MODEL_NAME", table = "TT_CARS") // this is the column name I would like to retrieve from the TT_CARS table
private String modelName;
// getters and setters
}
You can use #Formula. It is read-only calculated column that can be retrieved by the custom subquery. It does not present in the target table.
Defines a formula (derived value) which is a SQL fragment that acts as
a #Column alternative in most cases. Represents read-only state.
Example:
#Entity
#Table(name = "TT_OPTIONS")
public class Options {
#Id
#Column(name = "ID")
private Long id;
#Column(name = "DESCRIPTION", nullable = false)
private String description;
#Column(name = "MODEL_ID")
private Long modelId;
#Formula("(select TT_CARS.MODEL_NAME from TT_CARS where TT_CARS.ID = MODEL_ID)")
private String modelNameFormula;
}
#Entity
#Table(name = "TT_CARS")
public class Cars {
#Id
#Column(name = "ID")
private Long id;
#Column(name = "MODEL_NAME")
private String modelName;
}
Hibernate generated native query:
select
options0_.id as id1_4_0_,
options0_.description as descript2_4_0_,
options0_.model_id as model_id3_4_0_,
(select
TT_CARS.MODEL_NAME
from
TT_CARS
where
TT_CARS.ID = options0_.MODEL_ID) as formula1_0_
from
tt_options options0_
where
options0_.id=?
#SecondaryTable designed for #OneToOne relationship to map multiple tables to the same entity. It will not work for the #ManyToOne relationship.
I'm working on a Spring-Boot project with a H2 database. I have two entities Portfolio and Report, and there is a many-to-many association between the two.
I want those entities to be audited, so I followed this tutorial to audit through an AuditorAware interface with custom fields.
The two entities are well audited, the columns are created in the database. However, the join table portfolio_reports is not audited. How can I audit the join table as well ?
Portfolio.java
#Entity
#Table(name = "portfolio")
public class Portfolio extends Auditable<String> implements Serializable {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name = "name")
#Unique
private String name;
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.PERSIST)
#JoinTable(name = "portfolio_report", joinColumns = #JoinColumn(name = "portfolio_id"), inverseJoinColumns = #JoinColumn(name = "report_id"))
private List<Report> reports;
// Getters and setters
}
Report.java
#Entity
#Table(name = "report")
public class Report extends Auditable<String> implements Serializable {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name = "axioma_id")
private Long axiomaId;
#Column(name = "name")
private String name;
#AuditJoinTable
#ManyToMany(mappedBy = "reports", cascade = CascadeType.PERSIST, fetch = FetchType.LAZY)
private List<Portfolio> portfolios;
// Getters and setters
}
Auditable.java
#MappedSuperclass
#EntityListeners(AuditingEntityListener.class)
public abstract class Auditable<U> {
#Version
#Column(name = "version_no")
protected Long versionNo;
#CreatedDate
#Temporal(TemporalType.TIMESTAMP)
#Column(name = "created_date")
protected Date createdDate;
#LastModifiedDate
#Temporal(TemporalType.TIMESTAMP)
#Column(name = "modified_date")
protected Date modifiedDate;
}
AuditorAwareImpl.java
public class AuditorAwareImpl implements AuditorAware<String> {
#Override
public Optional<String> getCurrentAuditor() {
return Optional.of("Admin");
}
}
PersistenceConfiguration.java
#Configuration
#EnableJpaAuditing(auditorAwareRef = "auditorAware")
public class PersistenceConfiguration {
#Bean
public AuditorAware<String> auditorAware() {
return new AuditorAwareImpl();
}
}
Problem:
Clearly here Auditable should add some column to your intermediate table that maintains relation between Portfolio and Report and that table is created behind the scene and you don't have access to that table in your program. Only hibernate can use that table to maintain relation between your entities and do join operation.
Solution:
Here you should make Join table that maintain Many to Many relation between Portfolio and Report explicit so that you can have entity like PortfolioReport in your program that can extends from Auditable. Please read the following post to see how to do that: The best way to map a many-to-many association with extra columns when using JPA and Hibernate
I am looking to create a DAO which represents a join of two tables with Java Hibernate. Here is the SQL I'd like to represent (Postgres 9.6 incase that matters):
SELECT tableOneValue, tableTwoValue
FROM table_one, table_two
WHERE table_one_filter = 2 AND table_one_id = table_two_id;
These tables have a OneToOne relationship.
Table1.java
#Entity
#Data
#Table(name="table_one")
public class TableOneDao implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "table_one_id")
private int tableOneId;
#Column(name = "table_one_value")
private String tableOneValue;
#Column(name = "table_one_filter")
private int tableOneFilter;
}
Table2.java
#Entity
#Data
#Table(name="table_two")
public class TableTwoDao implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "table_twp_id")
private int tableTwpId;
#Column(name = "table_two_value")
private String tableTwoValue;
}
I'm very new to hibernate so maybe this isn't the right way to think with it. What I would love to do is define a SomeDao class where I can do: daoManager.findAll(SomeDao.class, Pair.of("tableOneFilter", 2));
This would return a List<SomeDao> where we get all the rows that satisfy tableOneFilter == 2.
You need to use the #OneToOne and #JoinColumn annotation.
Pay special attention to the userDetail attribute mapping.
For example, the user class:
#Entity
#Table(name = "USERS")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "USR_ID")
private long id;
#Column(name = "USERNAME", nullable = false, unique = true)
private String username;
#Column(name = "PASSWORD")
private String password;
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name="USR_DET_ID")
private UserDetail userDetail;
// Add Constructor, Setter and Getter methods
}
And this user details class:
#Entity
#Table(name = "USER_DETAILS")
public class UserDetail {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "USR_DET_ID")
private long id;
#Column(name = "FIRST_NAME")
private String firstName;
#Column(name = "LAST_NAME")
private String lastName;
#Column(name = "EMAIL")
private String email;
#Column(name = "DBO")
private LocalDate dob;
// Add Constructor, Setter and Getter methods
}
Check the full code here.
Here is a JPA query which will work with your existing entity structure with the latest version of hibernate.
SELECT t1.tableOneValue, t2.tableTwoValue
FROM TableOneDao AS t1 JOIN TableTwoDao AS t2 ON t1.table_one_id = t2.table_two_id
WHERE t1.table_one_filter = ?
You can write a JPQL statement which is much better. Here is the sample solution:
SELECT NEW com.test.package.dao(t1.valueOne, t2.valueTwo)
FROM table_one t1 JOIN table_two t2
WHERE t1.filter = 2 AND t1.id = t2.id;
Please refer to this link and jump to the section where it mentions Result Classes (Constructor Expressions). Hope it helps. Thanks.
I'm using hibernate-core:3.3.1.GA
I have three mappings:
class PlayerAccount:
#Entity
#Table(name = "player_account")
public class PlayerAccount {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private int id;
#ManyToOne(targetEntity = Player.class, fetch = FetchType.EAGER)
#JoinColumn(name="player_id")
private Player player;
//GET, SET
}
class PlayerAchievements:
#Entity
#Table(name="player_achievement")
public class PlayerAchievement {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private int id;
#ManyToOne(targetEntity = Player.class, fetch = FetchType.EAGER)
#JoinColumn(name = "player_id")
private Player player;
//GET, SET
}
and class Player
#Entity
#Table(name = "player")
#Inheritance(strategy = InheritanceType.JOINED)
public class Player {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private int id;
#Column(name = "ps_id")
private String psId;
#Column(name = "login")
private String login;
#Column(name = "password")
private String password;
#Column(name = "email")
private String email;
//GET, SET
}
Issue:
When I try to write a simple criteria query like the following:
Criteria criteria = getSession().createCriteria(PlayerAccount.class);
criteria.add(Restrictions.eq("playerId", playerId));
criteria.list();
The resulting sql-query contains joins have the following view:
SELECT
-- columns to select
FROM player_account this_
LEFT OUTER JOIN player player2_
ON this_.player_id=player2_.id
LEFT OUTER JOIN external_partner_player player2_1_
ON player2_.id=player2_1_.player_id
LEFT OUTER JOIN player_achievement achievemen3_
ON player2_.id=achievemen3_.player_id
WHERE player_id = 2362189
The thing is player_achievements may contain more than one row with the same player_id value. Since we probably have a duplicated result in that criteria query. How to fix that using hibernate whithout the writing an sql-query?
Because the Fetch Types are eager. That means that you always want the entities loaded when you load the main entity.
You can use FetchType.LAZY for best perform. Here explains better: https://howtoprogramwithjava.com/hibernate-eager-vs-lazy-fetch-type/
You need to do SELECT DISTINCT, like this:
criteria.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
I use hibernate and spring-data. There are two tables with many-to-many relationship.
#Entity
#Table(name = "FirstEntity")
public class FirstEntity {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "first_entity_id")
private Long id;
#Column(name = "first_entiry_name")
private String name;
/* getters and setters are below*/
}
#Entity
#Table(name = "SecondEntity")
public class SecondEntity {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "second_entity_id")
private Long id;
#Column(name = "second_entiry_name")
private String name;
#Column(name = "second_entiry_desc")
private String description;
/* getters and setters are below*/
}
And entity for cross-reference table.
#Entity
#Table(name = "FirstSecondEntity")
public class FirstSecondEntity {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "first_second_entity_id")
private Long id;
#Column(name = "first_entity_id")
private Long firstEntityId;
#Column(name = "second_entity_id")
private Long secondEntityId;
/* getters and setters are below*/
}
I need SELECT like this
SELECT FirstEntity.name, SecondEntity.name, SecondEntity.description FROM SecondEntity INNER JOIN FirstSecondEntity ON SecondEntity.id = FirstSecondEntity.secondEntityId INNER JOIN User ON FirstEntity.id = FirstSecondEntity.firstEntityId
i.e. I need all records from cross-reference table where instead of ids there is actual info from entities.
Inserting this query into #Query annotation in my CrudRepository-extended class doesn't work because of
ERROR [main][org.hibernate.hql.internal.ast.ErrorCounter] Path expected for join!
So I need your help.
Your join table is all screwed up. In this case, you actually don't even need the join table as a hibernate mapping:
In Second Entity add the following list:
#ManyToMany(fetch = FetchType.LAZY)
#JoinTable(name = "FirstSecondEntity",
joinColumns = {
#JoinColumn(name = "first_entity_id",
nullable = false,
updatable = false) },
inverseJoinColumns = {
#JoinColumn(name = "second_entity_id",
nullable = false,
updatable = false) },
)
private List<FirstEntity> firstEntities;
In FirstEntity add the following list:
#ManyToMany(fetch = FetchType.LAZY,
mappedBy = "firstEntities")
private List<SecondEntity> secondEntities;