Hibernate auto increment ID and a composite key

Question

I am using hibernate version 5.2.4 and postgresql v 9.4 and trying a create an annotated class which will help me build a table as below:

ID | client_name | company_name  |  email      
---+-------------+----------------------------
 1 |    bob      |    smith's    |
 2 |    mark     |  JK warehouse |

Where in 'ID' should be auto-incremented value and a composite key with client_name and company_name. The composite keys are not referencing from any table.

I was able to achieve this partially with @EmbeddedId and the @Embeddable as follows:

@Embeddable
public class ClientId implements Serializable {

    @Column(name = "client_name")
    private String clientName;

    @Column(name = "company_name")
    private String companyName;

....
}

@Entity(name = "ClientDetails")
@Table(name = "clientdetails")
public class ClientDetails {

    @EmbeddedId
    private ClientId id;

    private String email;

...}

Which results in table as follows:

     Column    |          Type          | Modifiers | Storage  
--------------+------------------------+-----------+----------
 client_name  | character varying(255) | not null  | extended 
 company_name | character varying(255) | not null  | extended 
 email        | character varying(255) |           | extended

but not able to incorporate the auto increment ID column. Also I tried using @Idclass and was not successful. I tried to google and found other scenario where the requirement was either to contain the Id within embeddable class or had reference to other tables, so finally decided to post here for help.

Many thanks.

Update: I managed to create a composite key using @IdClass and an Id with @GeneratedValue as follows:

@Entity
@Table(name = "clientdetails")
@IdClass(ClientId.class)
public class ClientDetails {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", updatable = false, nullable = false)
    private Long id;

    @Id
    @Column (name="client_name")
    private String clientName;

    @Id
    @Column (name="company_name")
    private String companyName;

    @Column (name="client_email")
    private String email;
....
}

  client_name | company_name | id |  client_email
-------------+--------------+----+-----------------
 bob          | smith's       |    | abc@xyz.com
 mark         | JK warehouse  |    | abc@xyz.com
(2 rows)

But this does not auto populate values for Id, please help

score 0 · Answer 1 · answered Dec 13 '16 at 08:12

0

Try this:

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE)
private Integer gid;

You could also try UUIDs as identificators. Here you are the way I generate UUIDs:

@Id
@Column(name = "ETAPA_ID", columnDefinition = "uuid")
@Type(type = "org.hibernate.type.PostgresUUIDType")
@GenericGenerator(name = "uuid2", strategy = "uuid2")
@GeneratedValue(generator = "uuid2")
private UUID id;

answered Dec 13 '16 at 08:12

joninx

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Remember that UUIDs are assigned only after the entities are saved into db. It'd be advisable to add uuid-ossp extension in postgresql db. – joninx Dec 14 '16 at 07:45
Is it possible to have composite ID as (client_name & company_name) and generate ID's i.e., the uniqueness is only on client_name & company_name. With Id, client_name and company_name in Idclass, the uniqueness applies to all the 3 columns and does not stop from creating multiple entries with same client_name and company_name poc=# select * from clientdetails; ad118f6e | Mark | JK warehouse | 213e63e4 | Mark | JK warehouse | – kiran Dec 14 '16 at 20:53
I think I found what I am looking for here [link] http://stackoverflow.com/questions/34528450/multiple-hibernate-sequence-generators-for-one-entity-with-postgresql – kiran Dec 14 '16 at 21:01

Hibernate auto increment ID and a composite key

1 Answers1