How to use spring Repository without @Id?

Question

I'm using spring CrudRepository throughout my application. Now I want to also create one for an @Entity that does not have an @Id. Is that possible at all?

//probably ID is always required?
public interface Repository<T, ID extends Serializable>

do you mean that your entity doesn't have an id at all or it is some kind of embedded structure? Could you show your entity code? — S. Pauk, Apr 10 '15 at 12:54
if your entities in your database don't have a PRIMARY KEY (ID), then you've got bigger problems. — EpicPandaForce, Apr 10 '15 at 12:57
@bpa.mdl it's simply not possible, as stated in the accepted answer. — membersound, Feb 22 '19 at 21:14

S. Pauk · Accepted Answer · 2016-01-29T12:38:13.813

41

JPA requires that every entity has an ID. So no, entity w/o an ID is not allowed.

Every JPA entity must have a primary key.

from JPA spec

You may want to read more about how JPA handles a case when there's no id on the DB side from here (see 'No Primary Key').

edited Jan 29 '16 at 12:38

answered Apr 10 '15 at 12:49

S. Pauk

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use all of the columns as the id does't work in hibernate if any column is null – KennyXu Nov 08 '18 at 06:45

epox · Answer 2 · 2022-12-16T00:23:51.217

Use @IdClass (composite key)

Yes, this is possible. This approach can be used when you read from a DB view. The below example demonstrates how to mark all (2, in the given example) columns as the composite ID:

import java.io.Serializable;
import lombok.Data;          // auto-generates  AllArgs contractor, getters/setters, equals, and hashcode 

@Data
@Entity
@IdClass(MyEntity.class)                         // <--this is the extra annotation to add
@Table(name = "my_table")
public class MyEntity implements Serializable{   // <--this is the extra interface to add
  @Id                                            // annotate each column with @Id
  private String column1;

  @Id                                            // annotate each column with @Id
  private String column2;
}

The above MyEntity uses the full record state as the key:
--so, in addition to @EqualsAndHashcode, do flag the class with Serializable interface;
--annotate each field with @ID
In your <T, ID> repository say the ID is your full (entity) class:

interface MyEntityRepo extends CrudRepository<MyEntity, MyEntity> {
                                                        // ^^^the full record is the ID

How to use spring Repository without @Id?

3 Answers3

Use @IdClass (composite key)

Linked