[JAVA] Generate a serial number with Hibernate (JPA) TableGenerator and store it in the Id of String.

Introduction

When persisting Hibernate Entity, I want to use @GeneratedValue annotation for @Id annotated field and set it to CHAR type column.

However, due to the specifications of the business FW adopted, there is a separate sequence serial number acquisition table (sequence_mng) instead of SEQUENCE of DBMS (SQL Server), and sequence_mng is not used to maintain consistency when creating a new record. It must not be.

The column should be BIGINT too! I think, but it can't be helped because there is something like "zero padding and fixed digit" belief.

Prerequisites

Execution environment

・ JDK1.8 ・ Hibernate (5.2.10.FINAL) · SQL Server 2016

Sequence management table

sequence_mng

CREATE TABLE sequence_mng (
	colname VARCHAR(40) NOT NULL,
	nextvalue BIGINT NOT NULL,
	PRIMARY KEY colname
);

Sequence grant target table

partner

CREATE TABLE m_partner (
	partner_cd CHAR(6) NOT NULL,
	partner_nm NVARCHAR(60) NOT NULL,
        -- OMITTED
        PRIMARY KEY partner_cd
);

Like this, when you try to make it permanent by calling save () etc. -Get the record where the colname of sequence_mng is "partner_cd" -Store nextvalue in partnerCd of Partner.class ・ Next value ++ I want to make it work based on Annotation.

Table Generator trial

And with this pattern, I feel like I can use GenerationType.TABLE. just like this

Partner.java(Failure)

@Entity
@Table(name = "partner")
public class Partner {

    @Id
    @GeneratedValue(strategy = GenerationType.TABLE, generator = "SEQ_TBL_PARTNER")
    @TableGenerator(name = "SEQ_TBL_PARTNER", 
      table = "sequence_mng",
      pkColumnName = "colname",
      valueColumnName = "nextvalue",
      pkColumnValue = "partner_cd")
    @Column(name = "partner_cd", unique = true, nullable = false, length = 6)
    private Integer partnerCd;

    @Column(name = "partner_nm", nullable = false)
    private String partnerNm;
//The following is omitted
}

However, the substance of @TableGenerator org.hibernate.id.enhanced.TableGenerator Actually with'org.hibernate.id.IdentifierGeneratorHelper#getIntegralDataTypeHolder' @Id field does not allow except long (Long), BigDecimal IdentifierGenerationException("Unknown integral data type for ids : StringType()) It doesn't move next to it. As mentioned above, the column attributes cannot be changed.

Customize

Therefore, I will create a StringTableGenerator that inherits TableGenerator and make it work. StringTableGenerator.java Create a StringTableGenerator that inherits from TableGenerator.

StringTableGenerator.java

package sample.hibernate.id;

import org.hibernate.MappingException;
import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.id.IdentifierGeneratorHelper;
import org.hibernate.id.IntegralDataTypeHolder;
import org.hibernate.id.enhanced.TableGenerator;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.type.BigDecimalType;
import org.hibernate.type.Type;

import java.io.Serializable;
import java.util.Properties;

/**
 * TableGenerator (Supports string columns)
 */
public class StringTableGenerator extends TableGenerator {

  @Override
  public void configure(Type type, Properties params, ServiceRegistry serviceRegistry)
    throws MappingException {
    super.configure(new BigDecimalType() , params, serviceRegistry);
  }

  @Override
  public Serializable generate(SharedSessionContractImplementor session, Object obj) {
    return super.generate(session, obj).toString();
  }

}

configure () method

Since StringType comes as the first argument, replace it with BigDecimalType () before passing it to the parent class (^^)

generate () method

The value returned from the parent class is BigDecimal, so replace it with a String before returning it. that's all.

Annotation settings

Then, rewrite the Entity that actually generates the sequence as follows.

Partner.java

@Entity
@Table(name = "partner")
public class Partner implements Serializable {
  @Id
  @GeneratedValue(strategy = GenerationType.TABLE, generator = "CUSTOM_SEQ")
  @GenericGenerator(strategy = "sample.hibernate.id.StringTableGenerator", 
    name = "CUSTOM_SEQ", parameters = {
    @Parameter(name = "segment_value", value = "partner_cd"),
    @Parameter(name = "table_name", value = "sequence_mng"),
    @Parameter(name = "segment_column_name", value = "colname"),
    @Parameter(name = "value_column_name", value = "nextvalue")
  })
  @Column(name = "partner_cd", unique = true, nullable = false, length = 6)
  private String partnerCd;

  @Column(name = "partner_nm", nullable = false)
  private String partnerNm;
 
(The following is omitted)

Change from @TableGenerator, which has a fixed class, to @GenericGenerator, and specify that the StringTableGenerator created earlier should be used. Note that the parameters also change their names.

With the above changes, a serial number will be generated and set in the String field as well.

Finally

Click here for Sequence Generator (almost original material) https://stackoverflow.com/questions/12517421/how-to-map-a-string-to-db-sequence-in-hibernate

Easy-to-understand description of Table Generator http://d.hatena.ne.jp/taedium/20070627/p1

This is also an easy-to-understand Table Generator http://qiita.com/KevinFQ/items/a6d92ec7b32911e50ffe

Digression

Hibernate changes the package structure and class name from time to time, so The materials out there quickly become obsolete.

If you think it's strange-it doesn't move, it's faster to look at the source. This time, the @Parameter name attribute did.

I couldn't find any other TableGenerator and StringType support, so I'll enter it in the hope that it will be useful to someone. then.