Spring Boot i18n with database stored messages

ApiDocConfig.java

package io.github.susimsek.springbootdemorest.config;

import io.swagger.v3.oas.models.parameters.Parameter;
import org.springdoc.core.customizers.OperationCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class ApiDocConfig {

    @Bean
    public OperationCustomizer customize() {
        return (operation, handlerMethod) -> operation.addParametersItem(
                new Parameter()
                        .in("header")
                        .required(false)
                        .example("en")
                        .description("Language Header")
                        .name("Accept-Language"));
    }
}

application.yml

spring:
  datasource:
    url: jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
    driver-class-name: org.h2.Driver
    username: sa
    password: password
  jpa:
    hibernate:
      ddl-auto: update
    properties:
      javax:
        persistence:
          validation:
            mode: none
    open-in-view: false
    defer-datasource-initialization: true
  h2:
    console:
      enabled: true

data.sql

INSERT INTO messages (locale, code, content)
VALUES ('en', 'error.invalid.size', 'size must be between {min} and {max}');

INSERT INTO messages (locale, code, content)
VALUES ('tr', 'error.invalid.size', 'boyut {min} ile {max} arasında olmalıdır');

DatabaseMessageSource.java

package io.github.susimsek.springbootdemorest.message;

import io.github.susimsek.springbootdemorest.domain.Message;
import io.github.susimsek.springbootdemorest.repository.MessageRepository;
import lombok.AccessLevel;
import lombok.RequiredArgsConstructor;
import lombok.experimental.FieldDefaults;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.support.ReloadableResourceBundleMessageSource;
import org.springframework.stereotype.Component;

import java.text.MessageFormat;
import java.util.Locale;

@Slf4j
@Component("messageSource")
@FieldDefaults(level = AccessLevel.PRIVATE)
@RequiredArgsConstructor
public class DatabaseMessageSource extends ReloadableResourceBundleMessageSource {

    final MessageRepository messageRepository;

    @Override
    protected MessageFormat resolveCode(String code, Locale locale) {
        return messageRepository.findByCodeAndLocale(code, locale.getLanguage())
                .map(message -> new MessageFormat(message.getContent(), locale))
                .orElse(super.resolveCode(code, locale));
    }

    @Override
    protected String resolveCodeWithoutArguments(String code, Locale locale) {
        return messageRepository.findByCodeAndLocale(code, locale.getLanguage())
                .map(Message::getContent)
                .orElse(super.resolveCodeWithoutArguments(code, locale));
    }
}

Message.java

package io.github.susimsek.springbootdemorest.domain;

import lombok.*;
import lombok.experimental.FieldDefaults;

import javax.persistence.*;

@Entity
@Table(name = "messages")
@FieldDefaults(level = AccessLevel.PRIVATE)
@Getter
@Setter
@ToString
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class Message {

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

    String locale;

    String code;

    String content;
}

MessageRepository.java

package io.github.susimsek.springbootdemorest.repository;

import io.github.susimsek.springbootdemorest.domain.Message;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.Optional;

public interface MessageRepository extends JpaRepository<Message, Long> {
    Optional<Message> findByCodeAndLocale(String code, String locale);
}

pom.xml

<properties>
		<java.version>17</java.version>
		<springdoc.version>1.6.6</springdoc.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springdoc</groupId>
			<artifactId>springdoc-openapi-ui</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-validation</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>
		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springdoc</groupId>
				<artifactId>springdoc-openapi</artifactId>
				<version>${springdoc.version}</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>