java - Hibernate 5.1.x naming Strategy (backward compatible with Hibernate 4.x)

Question

I'm using Spring Boot 1.3.3.RELEASE. By default Spring Boot uses the Hibernate Version 4.x. I'm trying to use new Hibernate i.e 5.1.0 FINAL (as of now).

I'm using Gradle so to override the Hibernate Version I've added the following line

ext['hibernate.version']="5.1.0.Final"

followed the steps of SpringBoot 1.3.0 support hibernate 5?

I'm using following for naming Strategy

spring.jpa.properties.hibernate.naming.implicit-strategy: org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyHbmImpl

spring.jpa.properties.hibernate.naming.physical_strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

I've have a Entity class

@Entity
public class AppUser {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @NotNull
    @Length(max = 100)
    private String username;

    @NotNull
    @Length(max = 100)
    private String firstName;

    @NotNull
    @Length(max = 100)
    private String lastName;

    @Length(max = 100)
    private String middleName;

    @NotNull
    @Length(max=100)
    private String email;

    @NotNull
    @Length(max = 100)
    private String password;

    @NotNull
    private boolean enabled;

}

On Hibernate 4.x it executes the query

create table app_user (
        id bigint not null auto_increment,
        email varchar(100) not null,
        enabled bit not null,
        first_name varchar(100) not null,
        last_name varchar(100) not null,
        middle_name varchar(100),
        password varchar(100) not null,
        username varchar(100) not null,
        primary key (id)
    )

on 5.x it executed the query

create table AppUser (
        id bigint not null auto_increment,
        email varchar(100) not null,
        enabled bit not null,
        firstName varchar(100) not null,
        lastName varchar(100) not null,
        middleName varchar(100),
        password varchar(100) not null,
        username varchar(100) not null,
        primary key (id)
    )

How can I set the naming strategy such that Hibernate Uses 5.x underscore (as 4.x) on Table name and Column Name

Answer 1

Firstly, you don't need org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

because of it does nothing and is used by Hibernate as default.

Hibernate 5 doesn't have a strategy that you want. All strategies are JPA compliant (generate names like AppUser). So you need to implement your own.

For an example a physical naming strategy

public class UnderscorePhysicalStartegy extends PhysicalNamingStrategyStandardImpl {

    @Override
    public Identifier toPhysicalTableName(Identifier name, JdbcEnvironment context) {
        return context.getIdentifierHelper()
                .toIdentifier(NamingStrategyUtils.classToName(name.getText()));
    }

}

It uses NamingStrategyUtils.

Keep in mind, if you specify an explicit name

@Entity
@Table(name = "AppUser")
public class AppUser {

}

you will have anyway a table name app_user. If you don't want such behavior use an implicit naming strategy.

I did some research work on naming strategies. You can refer Hibernate5NamingStrategy, it generates table and column names with underscores like you need and constraint names (unique, foreign key) as well.

This class is used to generate names: HibernateNamingStrategy.

How to use Hibernate5NamingStrategy

The naming strategy can be configured using StrategyOptions.

For example, to use strategy without the prefixes (like f_):

StrategyOptions options = StrategyOptions.builder().withoutPrefixes().build();
Hibernate5NamingStrategy strategy = new Hibernate5NamingStrategy(options);

Other examples: Hibernate 5 Implicit Naming Strategy

Except that, ImprovedNamingStrategy for Hibernate 5 can be used to simulate the behaviour of Hibernate 4 ImprovedNamingStrategy.