I have an entity
#Entity
public class Book {
#Id
#Column(name = "book_id")
#SequenceGenerator(name = "book_book_id_seq", sequenceName = "book_book_id_seq", allocationSize = 1)
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "book_book_id_seq")
private Long id;
// getter, setter & other fields
}
with schema
CREATE TABLE book
(
book_id bigint NOT NULL DEFAULT nextval('book_book_id_seq'::regclass),
CONSTRAINT book_pkey PRIMARY KEY (book_id)
)
What I want to achieve is sometime I would like to use sequence/id generated by database, but sometime the data is created at other place and I would like to create with existing (manual) id.
I can't set the id manually with Spring Data JPA way (using CrudRepository) or JPA way (using EntityManager), but no issue with native query. Is this JPA limitation? Any workaround for my issue?
Book book01 = new Book();
bookRepo.save(book01); // Book with id 1 is created
Book book02 = new Book();
book02.setId(5555L);
bookRepo.save(book02); // Does not create book with id 5555, but 2
Query nativeQuery = entityManager.createNativeQuery("INSERT INTO book VALUES (6666);");
nativeQuery.executeUpdate(); // Book with id 6666 is created
Query nativeQuery02 = entityManager.createNativeQuery("INSERT INTO book DEFAULT VALUES;");
nativeQuery02.executeUpdate(); // Book with id 3 is created
I am using PostgreSQL 9.4, Hibernate 5 and Java 8.
On persist, if a field is annotated with #GeneratedValue, it will generate the ID with whatever strategy is specified. Then it will set value of the id field with the generated value. So if the id is manually set using setId() before persisting, this will just be overriden.
If you want, you can use em.persist for auto-generated IDs. Then use native SQL for manually setting the Id, since native SQLs will bypass whatever mapping you have on your entity.
Yes, by default Hibernate org.hibernate.id.SequenceGenerator always generate new id. What you should do is to override public Serializable generate(SessionImplementor session, Object obj) method, where if your obj (cast to your entity first) has id, then return the id, else get it from database sequence.
Related
We use a dockerized postgres database and have hibernate auto-generate the tables (using spring.jpa.hibernate.ddl-auto: create) for our integration tests. Using something like H2 is not an option because we do some database-specific operations in a few places, e.g. native SQL queries.
Is there any way to avoid id collisions when all entities use auto-incremented ids? Either by offsetting the start id or, better yet, having all tables use a shared sequence?
Schema is created when the docker container is launched, tables are created by Spring Data JPA/Hibernate
Example
Examples use kotlin syntax and assumes the "allopen"-plugin is applied for entities.
Sometimes we've had bugs where the wrong foreign key was used, e.g. something like this:
#Entity
class EntityOne(
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", nullable = false, columnDefinition = "SERIAL")
var id: Long,
)
#Entity
class EntityTwo(
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", nullable = false, columnDefinition = "SERIAL")
var id: Long,
)
#Entity
class JoinEntity(
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", nullable = false, columnDefinition = "SERIAL")
var id: Long,
#ManyToOne
#JoinColumn(name = "entity_one_id")
var entityOne: EntityOne,
#ManyToOne
#JoinColumn(name = "entity_two_id")
var entityTwo: EntityTwo,
)
#Repository
interface JoinEntityRepository : JpaRepository<JoinEntity, Long> {
//
// Bug here! Should be "WHERE entityOne.id = :entityOneId"
//
#Query("SELECT entityTwo FROM JoinEntity WHERE entityTwo.id = :entityOneId")
fun findEntityTwoByEntityOneId(entityOneId: Long): Collection<EntityTwo>
}
These bugs can in some circumstances be very hard to find because when the table is created, there may very well be an Entity2 with the same id as some Entity1, and so the query succeeds but the test fails somewhere down the line because while it is returning one or more Entity2, it's not the expected ones.
Even worse, depending on the scope of the test it may pass even if the wrong entity is fetched, or fail only when tests are run in a specific order (due to ids getting "out of sync"). So ideally it should fail to even find an entity when the wrong id is passed. But because the database structure is created from scratch and the ids are auto-incremented they always start at 1.
I found a solution to this.
In my resources/application.yml (in the test folder, you most likely do not want to do this in your main folder) I add spring.datasource.initialization-mode: always and a file data.sql.
The contents of data.sql are as follows:
DROP SEQUENCE IF EXISTS test_shared_sequence;
CREATE SEQUENCE test_shared_sequence;
ALTER TABLE entity_one ALTER COLUMN id SET DEFAULT nextval('test_shared_sequence');
ALTER TABLE entity_two ALTER COLUMN id SET DEFAULT nextval('test_shared_sequence');
After Spring has auto-generated the tables (using spring.jpa.hibernate.ddl-auto: create) it will run whatever is in this script, and the script will change all tables to auto-generate ids based on the same sequence, meaning that no two entities will ever have the same id regardless of which table they're stored in, and as such any query that looks in the wrong table for an id will fail consistently.
I'm trying to use Map in Spring Data JPA to handle the relationship to store records of equipment quantity.
I followed this guide to create the entity.
Meeting{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "meeting_id", updatable = false)
#JsonIgnore
private int id;
#ElementCollection
#MapKeyColumn(name = "equipment_type")
#MapKeyEnumerated(EnumType.STRING)
private Map<EquipmentType, Integer> equipment = new HashMap<>();
}
EquipmentType is an Enum.
This is the table for the property:
CREATE TABLE IF NOT EXISTS meeting_equipment (
meeting_id INTEGER NOT NULL REFERENCES meeting (meeting_id),
equipment_type VARCHAR(10) NOT NULL,
quantity INTEGER NOT NULL DEFAULT 0
);
Once I try to create a meeting entity, I get error ERROR:column "meeting_meeting_id" of relation "meeting_equipment" does not exist
May I know what's the problem here?
Your table meeting_equipment does not match what JPA is expecting.
It has a column meeting_id but your JPA implementation expects meeting_meeting_id
Either rename the column to the expected meeting_meeting_id or configure your mapping to use the current column name. I think this might do the trick:
#JoinTable(joinColumns={#JoinColumn(name="meeting_id")}
Of course, you probably can create your own naming strategy if you have many cases like this and want to keep your column names as they are.
I'm trying to use entities with a MySQL ndbcluster table. This table type doesn't allow foreign keys, but up until now it hasn't been a problem with my entities.
However, I have run into a bit of a problem, when I try to load an entity using the EntityManager's createNativeQuery method. I need to use this method due to my inability to do this: How to make a CriteriaBuilder join with a custom "on" condition?
My MySQL table looks like this:
CREATE TABLE `category` (
`id` SMALLINT(6) NOT NULL AUTO_INCREMENT,
`category_id` SMALLINT(6) NULL DEFAULT NULL,
PRIMARY KEY (`id`),
INDEX `category_id` (`category_id`)
)
COLLATE='utf8_general_ci'
ENGINE=ndbcluster
ROW_FORMAT=DEFAULT
If I change the table engine to innodb, and add foreign keys, the createNativeQuery method works fine.
My entity class looks like this:
#Entity
#Table(name = "category")
public class Category implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#Column(name = "id")
private Short id;
#OneToMany(mappedBy = "categoryId")
private List<Category> categoryList;
#JoinColumn(name = "category_id", referencedColumnName = "id")
#ManyToOne
private Category categoryId;
public Category() {
}
// getters and setters
}
Even without foreign keys, this entity works fine when I use the CriteriaBuilder for a query, but unfortunately not everything is possible with the CriteriaBuilder.
I get an error when I call getResultList on a Query object created with createNativeQuery. I don't know if this is a bug, or if something should be added to my entity class to make this work.
The error says:
Exception [EclipseLink-6044] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.QueryException
Exception Description: The primary key read from the row [ArrayRecord(
=> 2519
=> 2463
=> Tools)] during the execution of the query was detected to be null. Primary keys must not contain null.
Query: ReadAllQuery(referenceClass=Category sql="select * from `category`")
at org.eclipse.persistence.exceptions.QueryException.nullPrimaryKeyInBuildingObject(QueryException.java:895)
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:584)
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:560)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.buildObject(ObjectLevelReadQuery.java:717)
at org.eclipse.persistence.queries.ReadAllQuery.registerResultInUnitOfWork(ReadAllQuery.java:769)
...
My table contains 1 row, where id=1 and category_id=null, so there are no primary keys with a null-value, despite what the error says. If I remove that row or set category_id=1, I don't get an error.
Need help, please.
Managed to make it work by switching from EclipseLink (JPA 2.0) to OpenJPA (JPA 2.0). Seems like there is a bug somewhere in EclipseLink 2.3.2 and/or GlassFish 3.1.2.2.
I've used EclipseLink (JPA 2.0) in another project of mine, using a slightly different version Netbeans + GlassFish 3.1.1, where I used createNativeQuery on an entity class for a non-relational myisam table. This never caused any problem. It really must be a bug.
But problem solved. Bye, bye EclipseLink, hello OpenJPA.
The issue is case sensitivity. In MySQL your column "id" will be defined in the database as "ID" unless you quote it. If you switch your mappings to upper case it should fix the issue (i.e. "ID").
You could also quote the column name ("'id'")
or set the persistence unit property,
"eclipselink.jpa.uppercase-column-names"="true"
I am using JPA in my application. In one of the table, I have not used primary key (I know its a bad design).
Now the generated entity is as mentioned below :
#Entity
#Table(name="INTI_SCHEME_TOKEN")
public class IntiSchemeToken implements Serializable {
private static final long serialVersionUID = 1L;
#Column(name="CREATED_BY")
private String createdBy;
#Temporal( TemporalType.DATE)
#Column(name="CREATED_ON")
private Date createdOn;
#Column(name="SCH_ID")
private BigDecimal schId;
#Column(name="TOKEN_ID")
private BigDecimal tokenId;
public IntiSchemeToken() {
}
public String getCreatedBy() {
return this.createdBy;
}
public void setCreatedBy(String createdBy) {
this.createdBy = createdBy;
}
public Date getCreatedOn() {
return this.createdOn;
}
public void setCreatedOn(Date createdOn) {
this.createdOn = createdOn;
}
public BigDecimal getSchId() {
return this.schId;
}
public void setSchId(BigDecimal schId) {
this.schId = schId;
}
public BigDecimal getTokenId() {
return this.tokenId;
}
public void setTokenId(BigDecimal tokenId) {
this.tokenId = tokenId;
}
}
Here In my project, eclipse IDE shows ERROR mark(RED colored cross) on this class and the error is "The entity has no primary key attribute defined".
Can anyone tell me, How to create an entity without primary key ?
Thanks.
You can't. An entity MUST have a unique, immutable ID. It doesn't have to be defined as a primary key in the database, but the field or set of fields must uniquely identify the row, and its value may not change.
So, if one field in your entity, or one set of fields in your entity, satisfies these criteria, make it (or them) the ID of the entity. For example, if there is no way that a user can create two instances in the same day, you could make [createdOn, createdBy] the ID of the entity.
Of course this is a bad solution, and you should really change your schema and add an autogenerated, single-column ID in the entity.
If your Primary Key(PK) is a managed super class which is inherited in an entity class then you will have to include the mapped super class name in the persistence.xml file.
Look at the bug report:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=361042
If you need to define a class without primary key, then you should mark that class as an Embeddable class. Otherwise you should give the primary key for all entities you are defining.
You can turn off (change) validation that was added.
Go to workspace preferences 'Java Persistence->JPA->Errors/Warnings' next 'Type' and change 'Entity has no primary key' to 'Warnning'.
In addition to http://en.wikibooks.org/wiki/Java_Persistence/Identity_and_Sequencing#No_Primary_Key you can use some build-in columns like ROWID in Oracle:
Oracle legacy table without good PK: How to Hibernate?
but with care:
http://www.orafaq.com/wiki/ROWID
Entity frameworks doesn't work for all kind of data (like statistical data which was used for analysis not for querying).
Another solution without Hibernate
If
- you don't have PK on the table
- there is a logical combination of columns that could be PK (not necessary if you can use some kind of rowid)
-- but some of the columns are NULLable so you really can't create PK because of DB limitation
- and you can't modify the table structure (would break insert/select statements with no explicitly listed columns at legacy code)
then you can try the following trick
- create view at database with virtual column that has value of concatenated logical key columns ('A='||a||'B='||'C='c..) or rowid
- create your JPA entity class by this view
- mark the virtual column with #Id annotation
That's it. Update/delete data operations are also possible (not insert) but I wouldn't use them if the virtual key column is not made of rowid (to avoid full scan searches by the DB table)
P.S. The same idea is partly described at the linked question.
You need to create primary key ,If not found any eligible field then create auto increment Id.
CREATE TABLE fin_home_loan (
ID int NOT NULL AUTO_INCREMENT,
PRIMARY KEY (ID));
Just add fake id field.
In Postgres:
#Id
#Column(name="ctid")
String id;
In Oracle:
#Id
#Column(name="ROWID")
String rowid;
I'm currently creating some POJOs to connect to an existing database called User. The database already has a userid that I would like to use. However the framework creates an id field that it appends to the end of the table. How can I specify that the framework should use the pre-existing userid field and not create a new one?
You can use #AttributeOverride:
#Entity
#AttributeOverride(name = "id", column = #Column(name = "userid"))
public class User extends Model { ... }
To define your own primary key, have your models extend GenericModel instead of model and annotate your primary key with #Id. The model class enhances the generic model with an autogenerated id.
class User extends GenericModel{
#Id
Long userid;
}