I have a legacy application with a database that splits up the data into multiple schemas on the same physical database. The schemas are identical in structure.
I use a microservice using Spring Boot Data JPA to do work on a single schema. Then to avoid code repetition, I created a router service that forwards the request to the single schema microservice replica each with a different database connection. But I found that a bit overkill (but works)
I am trying to reduce it back down to a single microservice. I haven't been successful yet, but I set up the tables with the schema property.
#Table(
name = "alerts",
schema = "ca"
)
However, it gets confused when I try to do inheritance and #MappedSuperclass to reduce the code duplication.
In addition the #OneToMany breaks apart because of the inheritance getting errors like X references an unknown entity: Y
Basically is there a way of using inheritance on JPA that uses the same table structure with the difference being just the schema without copy and pasting too much code. Ideally I'd like to just pass a "schema" parameter to a DAO and it somehow does it for me.
In the end, we just need a data source that would route according to the situation. To do this a #Component that extends AbstractRoutingDataSource is used and a ThreadLocal to store the request context.
The ThreadLocal would be something like this (examples are using Lombok)
#AllArgsConstructor
public class UserContext {
private static final ThreadLocal<UserContext> context =
new ThreadLocal<>();
private final String schema;
public static String getSchema() {
return context.get().schema;
}
public static void setFromXXX(...) {
context.set(new UserContext(
...
));
}
}
A source for the data sources would be needed:
#Configuration
public class DataSources {
#Bean
public DataSource schema1() {
return build("schema1");
}
#Bean
public DataSource schema2() {
return build("schema2");
}
private DataSource buildDataSource(String schema) {
...
return new DriverManagerDataSource(url, username, password);
}
}
And finally the router which is marked as the #Primary data source to make sure it is the one that gets used by JPA.
#Component
#Primary
public class RoutingDatasource extends AbstractRoutingDataSource {
#Autowired
#Qualifier("schema1")
private DataSource schema1;
#Autowired
#Qualifier("schema2")
private DataSource schema2;
#Override
public void afterPropertiesSet() {
setTargetDataSources(
Map.of(
"schema1", schema1,
"schema2", schema2
)
);
super.afterPropertiesSet();
}
#Override
protected Object determineCurrentLookupKey() {
return UserContext.getSchema();
}
}
This avoids the code duplication when all that is different is a schema or even a data source.
I want to measure time of sql execution which will be run by MyBatis (Spring Boot project) and bind that with other request parameters, so I can get full info about performance issues regarding specific requests. For that case I have used MyBatis Interceptor on following way:
#Intercepts({
#Signature(
type = Executor.class,
method = "query",
args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class}),
#Signature(
type = Executor.class,
method = "query",
args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class})
})
public class QueryMetricsMybatisPlugin implements Interceptor {
#Override
public Object intercept(Invocation invocation) throws Throwable {
Stopwatch stopwatch = Stopwatch.createStarted();
Object result = invocation.proceed();
stopwatch.stop();
logExectionTime(stopwatch, (MappedStatement) invocation.getArgs()[0]);
return result;
}
}
Now when it come to binding with request, I want to store those metrics in request as attribute. I have tried this simple solution to get request, but that was not working since request was always null (I have read that this solution won't work in async methods, but with MyBatis Interceptor and its methods I think that's not the case):
#Autowired
private HttpServletRequest request;
So, the question is how properly get request within MyBatis interceptor?
One important note before I answer your question: it is a bad practice to access UI layer in the DAO layer. This creates dependency in the wrong direction. Outer layers of your application can access inner layers but in this case this is other way round. Instead of this you need to create a class that does not belong to any layer and will (or at least may) be used by all layers of the application. It can be named like MetricsHolder. Interceptor can store values to it, and in some other place where you planned to get metrics you can read from it (and use directly or store them into request if it is in UI layer and request is available there).
But now back to you question. Even if you create something like MetricsHolder you still will face the problem that you can't inject it into mybatis interceptor.
You can't just add a field with Autowired annotation to interceptor and expect it to be set. The reason for this is that interceptor is instantiated by mybatis and not by spring. So spring does not have chance to inject dependencies into interceptor.
One way to handle this is to delegate handling of the interception to a spring bean that will be part of the spring context and may access other beans there. The problem here is how to make that bean available in interceptor.
This can be done by storing a reference to such bean in the thread local variable. Here's example how to do that. First create a registry that will store the spring bean.
public class QueryInterceptorRegistry {
private static ThreadLocal<QueryInterceptor> queryInterceptor = new ThreadLocal<>();
public static QueryInterceptor getQueryInterceptor() {
return queryInterceptor.get();
}
public static void setQueryInterceptor(QueryInterceptor queryInterceptor) {
QueryInterceptorRegistry.queryInterceptor.set(queryInterceptor);
}
public static void clear() {
queryInterceptor.remove();
}
}
Query interceptor here is something like:
public interface QueryInterceptor {
Object interceptQuery(Invocation invocation) throws InvocationTargetException, IllegalAccessException;
}
Then you can create an interceptor that will delegate processing to spring bean:
#Intercepts({
#Signature(type = Executor.class, method = "query", args = { MappedStatement.class, Object.class,
RowBounds.class, ResultHandler.class }),
#Signature(type = Executor.class, method = "query", args = { MappedStatement.class, Object.class,
RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class}) })
public class QueryInterceptorPlugin implements Interceptor {
#Override
public Object intercept(Invocation invocation) throws Throwable {
QueryInterceptor interceptor = QueryInterceptorRegistry.getQueryInterceptor();
if (interceptor == null) {
return invocation.proceed();
} else {
return interceptor.interceptQuery(invocation);
}
}
#Override
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
#Override
public void setProperties(Properties properties) {
}
}
You need to create an implementation of the QueryInterceptor that does what you need and make it a spring bean (that's where you can access other spring bean including request which is a no-no as I wrote above):
#Component
public class MyInterceptorDelegate implements QueryInterceptor {
#Autowired
private SomeSpringManagedBean someBean;
#Override
public Object interceptQuery(Invocation invocation) throws InvocationTargetException, IllegalAccessException {
// do whatever you did in the mybatis interceptor here
// but with access to spring beans
}
}
Now the only problem is to set and cleanup the delegate in the registry.
I did this via aspect that was applied to my service layer methods (but you can do it manually or in spring mvc interceptor). My aspect looks like this:
#Aspect
public class SqlSessionCacheCleanerAspect {
#Autowired MyInterceptorDelegate myInterceptorDelegate;
#Around("some pointcut that describes service methods")
public Object applyInterceptorDelegate(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
QueryInterceptorRegistry.setQueryInterceptor(myInterceptorDelegate);
try {
return proceedingJoinPoint.proceed();
} finally {
QueryInterceptorRegistry.clear();
}
}
}
I'm wondering what the best way to load initial database data before the application starts? What I'm looking for is something that will fill my H2 database with data.
For example, I have a domain model "User" I can access users by going to /users but initially there won't be any users in the database so I have to create them. Is there anyway to fill the database with data automatically?
At the moment I have a Bean that gets instantiated by the container and creates users for me.
Example:
#Component
public class DataLoader {
private UserRepository userRepository;
#Autowired
public DataLoader(UserRepository userRepository) {
this.userRepository = userRepository;
LoadUsers();
}
private void LoadUsers() {
userRepository.save(new User("lala", "lala", "lala"));
}
}
But I very much doubt that is the best way of doing it. Or is it?
You can create a data.sql file in your src/main/resources folder and it will be automatically executed on startup. In this file you can add some insert statements, eg.:
INSERT INTO users (username, firstname, lastname) VALUES
('lala', 'lala', 'lala'),
('lolo', 'lolo', 'lolo');
Similarly, you can create a schema.sql file (or schema-h2.sql) as well to create your schema:
CREATE TABLE task (
id INTEGER PRIMARY KEY,
description VARCHAR(64) NOT NULL,
completed BIT NOT NULL);
Though normally you shouldn't have to do this since Spring boot already configures Hibernate to create your schema based on your entities for an in memory database. If you really want to use schema.sql you'll have to disable this feature by adding this to your application.properties:
spring.jpa.hibernate.ddl-auto=none
More information can be found at the documentation about Database initialization.
If you're using Spring Boot 2, database initialization only works for embedded databases (H2, HSQLDB, ...). If you want to use it for other databases as well, you need to change the initialization mode property:
spring.sql.init.mode=always # Spring Boot >=v2.5.0
spring.datasource.initialization-mode=always # Spring Boot <v2.5.0
If you're using multiple database vendors, you can name your file data-h2.sql or data-mysql.sql depending on which database platform you want to use.
To make that work, you'll have to configure the datasource platform property:
spring.sql.init.platform=h2 # Spring Boot >=v2.5.0
spring.datasource.platform=h2 # Spring Boot <v2.5.0
If I just want to insert simple test data I often implement a ApplicationRunner. Implementations of this interface are run at application startup and can use e.g. a autowired repository to insert some test data.
I think such an implementation would be slightly more explicit than yours because the interface implies that your implementation contains something you would like to do directly after your application is ready.
Your implementation would look sth. like this:
#Component
public class DataLoader implements ApplicationRunner {
private UserRepository userRepository;
#Autowired
public DataLoader(UserRepository userRepository) {
this.userRepository = userRepository;
}
public void run(ApplicationArguments args) {
userRepository.save(new User("lala", "lala", "lala"));
}
}
You can add a spring.datasource.data property to application.properties listing the sql files you want to run. Like this:
spring.datasource.data=classpath:accounts.sql, classpath:books.sql, classpath:reviews.sql
//or (depending on SB version)
spring.sql.init.data-locations=classpath:accounts.sql, classpath:books.sql, file:reviews.sql
The sql insert statements in each of these files will then be run, allowing you to keep things tidy.
If you put the files in the classpath, for example in src/main/resources they will be applied. Or replace classpath: with file: and use an absolute path to the file
If you want to run DDL type SQL then use:
spring.datasource.schema=classpath:create_account_table.sql
// depending on spring version
spring.sql.init.schema-locations=classpath:create_account_table.sql
Edit: these solutions are great to get you up and running quickly, however for a more production ready solution it would be worth looking at a framework such as flyway, or liquibase. These frameworks integrate well with spring, and provide a quick, consistent, version-controlled means of initialising schema, and standing-data.
There are multiple ways how to achieve this. I prefer to use one of following options:
Option 1: Initializing with CommandLineRunner bean:
#Bean
public CommandLineRunner loadData(CustomerRepository repository) {
return (args) -> {
// save a couple of customers
repository.save(new Customer("Jack", "Bauer"));
repository.save(new Customer("Chloe", "O'Brian"));
repository.save(new Customer("Kim", "Bauer"));
repository.save(new Customer("David", "Palmer"));
repository.save(new Customer("Michelle", "Dessler"));
// fetch all customers
log.info("Customers found with findAll():");
log.info("-------------------------------");
for (Customer customer : repository.findAll()) {
log.info(customer.toString());
}
log.info("");
// fetch an individual customer by ID
Customer customer = repository.findOne(1L);
log.info("Customer found with findOne(1L):");
log.info("--------------------------------");
log.info(customer.toString());
log.info("");
// fetch customers by last name
log.info("Customer found with findByLastNameStartsWithIgnoreCase('Bauer'):");
log.info("--------------------------------------------");
for (Customer bauer : repository
.findByLastNameStartsWithIgnoreCase("Bauer")) {
log.info(bauer.toString());
}
log.info("");
}
}
Option 2: Initializing with schema and data SQL scripts
Prerequisites:
application.properties
spring.jpa.hibernate.ddl-auto=none
Explanation:
Without ddl-auto SQL scripts will be ignored by
Hibernate and trigger default behavior - scanning project for
#Entity and/or #Table annotated classes.
Then, in your MyApplication class paste this:
#Bean(name = "dataSource")
public DriverManagerDataSource dataSource() {
DriverManagerDataSource dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName("org.h2.Driver");
dataSource.setUrl("jdbc:h2:~/myDB;MV_STORE=false");
dataSource.setUsername("sa");
dataSource.setPassword("");
// schema init
Resource initSchema = new ClassPathResource("scripts/schema-h2.sql");
Resource initData = new ClassPathResource("scripts/data-h2.sql");
DatabasePopulator databasePopulator = new ResourceDatabasePopulator(initSchema, initData);
DatabasePopulatorUtils.execute(databasePopulator, dataSource);
return dataSource;
}
Where scripts folder is located under resources folder (IntelliJ Idea)
Hope it helps someone
Update 04-2021: Both options are great to combine with Spring Profiles as this will help you to avoid creating additional config files making your life as the developer easy.
You can use something like this:
#SpringBootApplication
public class Application {
#Autowired
private UserRepository userRepository;
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
InitializingBean sendDatabase() {
return () -> {
userRepository.save(new User("John"));
userRepository.save(new User("Rambo"));
};
}
}
In Spring Boot 2 data.sql was not working with me as in spring boot 1.5
import.sql
In addition, a file named import.sql in the root of the classpath is executed on startup if Hibernate creates the schema from scratch (that is, if the ddl-auto property is set to create or create-drop).
Note very important if you insert Keys cannot be duplicated do not use ddl-auto property is set to update because with each restart will insert same data again
For more information you vist spring websit
https://docs.spring.io/spring-boot/docs/current/reference/html/howto-database-initialization.html
Spring Boot allows you to use a simple script to initialize your database, using Spring Batch.
Still, if you want to use something a bit more elaborated to manage DB versions and so on, Spring Boot integrates well with Flyway.
See also:
Spring Boot Database initialization
You can simply create a import.sql file in src/main/resources and Hibernate will execute it when the schema is created.
If you came here and nothing seems to work for you, then it might be the case that you are affected from some changes that were introduced with Spring Boot 2.5 and onwards.
Here is the total set of properties which I use for postgresql.
spring:
sql.init.mode: always <-----------------
datasource:
url: jdbc:postgresql://localhost:5432/products
username:
password:
jpa:
defer-datasource-initialization: true <------------------
hibernate:
ddl-auto: create-drop <----------------
database-platform: org.hibernate.dialect.PostgreSQLDialect
I have also marked with <--- the relevant properties for the current topic in order to achieve the following.
ORM vendor will create database schema for you from Java Entities model.
After database schema is created, initial data will be loaded to database from the file data.sql
Ps: Don't forget to add the file with initial data, data.sql under src/main/resources
Also as reference: Spring Boot 2.5 release notes
Here is the way I got that:
#Component
public class ApplicationStartup implements ApplicationListener<ApplicationReadyEvent> {
/**
* This event is executed as late as conceivably possible to indicate that
* the application is ready to service requests.
*/
#Autowired
private MovieRepositoryImpl movieRepository;
#Override
public void onApplicationEvent(final ApplicationReadyEvent event) {
seedData();
}
private void seedData() {
movieRepository.save(new Movie("Example"));
// ... add more code
}
}
Thanks to the author of this article:
http://blog.netgloo.com/2014/11/13/run-code-at-spring-boot-startup/
I solved similar problem this way:
#Component
public class DataLoader {
#Autowired
private UserRepository userRepository;
//method invoked during the startup
#PostConstruct
public void loadData() {
userRepository.save(new User("user"));
}
//method invoked during the shutdown
#PreDestroy
public void removeData() {
userRepository.deleteAll();
}
}
You're almost there!
#Component
public class DataLoader implements CommandLineRunner {
private UserRepository userRepository;
public DataLoader(UserRepository userRepository) {
this.userRepository = userRepository;
}
#Override
public void run(String... args) throws Exception {
LoadUsers()
}
private void LoadUsers() {
userRepository.save(new User("lala", "lala", "lala"));
}
}
you can register and event listener to achieve that like below:
#EventListener
public void seed(ContextRefreshedEvent event) {
userRepository.save(new User("lala", "lala", "lala"));
}
When the ContextRefreshEvent is fired, we get access to all autowired beans in the application — including models and repositories.
If someone are struggling in make this to work even following the accepted answer, for me only work adding in my src/test/resources/application.yml the H2 datasource details:
spring:
datasource:
platform: h2
url: jdbc:h2:mem:test;DB_CLOSE_DELAY=-1
driver-class-name: org.h2.Driver
username: sa
password:
If you want to insert only few rows and u have JPA Setup. You can use below
#SpringBootApplication
#Slf4j
public class HospitalManagementApplication {
public static void main(String[] args) {
SpringApplication.run(HospitalManagementApplication.class, args);
}
#Bean
ApplicationRunner init(PatientRepository repository) {
return (ApplicationArguments args) -> dataSetup(repository);
}
public void dataSetup(PatientRepository repository){
//inserts
}
You can use the below code. In the following code a database insertion occurs during the startup of the spring boot application.
#SpringBootApplication
public class Application implements CommandLineRunner {
#Autowired
private IService<Car> service;
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Override
public void run(String... args) throws Exception {
for(int i=1; i<=1000; i++) {
Car car = new Car();
car.setName("Car Name "+i);
book.setPrice(50 + i);
service.saveOrUpdate(car);
}
}
}
This will also work.
#Bean
CommandLineRunner init (StudentRepo studentRepo){
return args -> {
// Adding two students objects
List<String> names = Arrays.asList("udara", "sampath");
names.forEach(name -> studentRepo.save(new Student(name)));
};
}
The most compact (for dynamic data) put #mathias-dpunkt solution into MainApp (with Lombok #AllArgsConstructor):
#SpringBootApplication
#AllArgsConstructor
public class RestaurantVotingApplication implements ApplicationRunner {
private final VoteRepository voteRepository;
private final UserRepository userRepository;
public static void main(String[] args) {
SpringApplication.run(RestaurantVotingApplication.class, args);
}
#Override
public void run(ApplicationArguments args) {
voteRepository.save(new Vote(userRepository.getOne(1), LocalDate.now(), LocalTime.now()));
}
}
One possibility is using incorrect JDBC URL. make sure it is jdbc:h2:mem:testdb
I created a library that facilitates initial/demo data loading in a Spring Boot application. You can find it at https://github.com/piotrpolak/spring-boot-data-fixtures
Once the data fixtures starter is on the classpath, it will automatically try to load DICTIONARY data upon application startup (this behavior can be controlled by properties) - all you need to do is to register a bean implementing DataFixture.
I find loading initial data by code superior to loading it using SQL scripts:
the logic of your fixtures lives close to your application logic/domain model and it is subject to refactoring as your domain evolves
you benefit from incremental demo data updates - imagine a QA environment with some user data (that needs not to be lost after application deploy) but at the same time you want to add data for the new features you developed
Example data fixture:
/**
* You can have as many fixture classes as you want.
* #Order annotation is respected for the fixtures belonging to the same set.
* You can make your demo database to be incrementally updated with fresh data
* each time the application is redeployed - all you need to do is to write
* a good condition in `canBeLoaded()` method.
*/
#Component
public class InitialDataFixture implements DataFixture {
private final LanguageRepository languageRepository;
// ...
#Override
public DataFixtureSet getSet() {
return DataFixtureSet.DICTIONARY;
}
/**
* We want to make sure the fixture is applied once and once only.
* A more sophisticated condition can be used to create incremental demo data
* over time without the need to reset the QA database (for example).
*/
#Override
public boolean canBeLoaded() {
return languageRepository.size() == 0;
}
/**
* The actual application of the fixture.
* Assuming that data fixtures are registered as beans, this method can call
* other services and/or repositories.
*/
#Override
public void load() {
languageRepository.saveAll(Arrays.asList(
new Language("en-US"), new Language("pl-PL")));
}
}
The concept is inspired by the Symfony Doctrine Data Fixtures bundle.
For those using MysqlDriver, I tried using Init attribute of #bean annotation and it works.
After created the Schema and Data sql file in the path of resources\Scripts
Add the line in application.properties
spring.jpa.hibernate.ddl-auto=none
Edit the Application content:
package com.spring_mvaen.demo;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.jdbc.datasource.init.DatabasePopulator;
import org.springframework.jdbc.datasource.init.DatabasePopulatorUtils;
import org.springframework.jdbc.datasource.init.ResourceDatabasePopulator;
#SpringBootApplication
public class DemoApplication implements CommandLineRunner {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
#Override
public void run(String... arg0) throws Exception {
System.out.println("Hello world from Command Line Runner");
}
#Bean(name = "dataSource")
public DriverManagerDataSource dataSource() {
DriverManagerDataSource dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
dataSource.setUrl("jdbc:mysql://localhost:3306/db_spring_rest?useUnicode=true&useLegacyDatetimeCode=fa lse&serverTimezone=UTC&createDatabaseIfNotExist=true&allowPublicKeyRetrieval=true&useSSL=false");
dataSource.setUsername("root");
dataSource.setPassword("root");
// schema init
Resource initSchema = new ClassPathResource("scripts/schema.sql");
Resource initData = new ClassPathResource("scripts/data.sql");
DatabasePopulator databasePopulator = new ResourceDatabasePopulator(initSchema, initData);
DatabasePopulatorUtils.execute(databasePopulator, dataSource);
return dataSource;
}
}
If you want to do insert quick some queries, you can do with h2 data.sql queries as well
application.properties include:
spring.jpa.show-sql=true
spring.h2.console.enabled=true
spring.datasource.url=jdbc:h2:mem:testdb
#This directs the data.sql file and help it to run
spring.sql.init.data-locations=classpath:data.sql
spring.jpa.defer-datasource-initialization=true
data.sql file include:
INSERT INTO todo (id, username, description, target_date, is_done) VALUES (10001, 'lighteducation', 'Learn dance', CURRENT_DATE ,false);
INSERT INTO todo (id, username, description, target_date, is_done) VALUES (10002, 'lighteducation', 'Learn Angular14', CURRENT_DATE, false);
INSERT INTO todo (id, username, description, target_date, is_done) VALUES (10003, 'lighteducation', 'Learn Microservices', CURRENT_DATE,false);
P.S.: data.sql file should be inside src/main/resources
Your #Entity include
#Getter
#Setter
#AllArgsConstructor
#ToString
#Entity
public class Todo {
#Id
#GeneratedValue
private Long id;
private String username;
private String description;
private Date targetDate;
private boolean isDone;
protected Todo() {
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Todo todo = (Todo) o;
return id == todo.id;
}
#Override
public int hashCode() {
return Objects.hash(id);
}
}
That is it basically. it will be in memory, it means when you restart application data will arese and will be again same as queries show.
But it is easy for quick check
also you can access the path with http://localhost:8080/h2-console/ or you can edit the path from .properties file