Roll back A if B goes wrong. spring boot, jdbctemplate

Question

I have a method, \'databaseChanges\', which call 2 operations: A, B in iterative way. \'A\' first, \'B\' last. \'A\' & \'B\' can be Create, U

Answer 1

What you seem to be missing is a TransactionManager. The purpose of the TransactionManager is to be able to manage database transactions. There are 2 types of transactions, programmatic and declarative. What you are describing is a need for a declarative transaction via annotations.

So what you need to be in place for your project is the following:

Spring Transactions Dependency (Using Gradle as example)

compile("org.springframework:spring-tx")

Define a Transaction Manager in Spring Boot Configuration

Something like this

@Bean
public PlatformTransactionManager transactionManager(DataSource dataSource)
{
    return new DataSourceTransactionManager(dataSource);
}

You would also need to add the @EnableTransactionManagement annotation (not sure if this is for free in newer versions of spring boot.

@EnableTransactionManagement
public class AppConfig {
...
}

Add @Transactional

Here you would add the @Transactional annotation for the method that you want to participate in the transaction

@Transactional
public void book(String... persons) {
    for (String person : persons) {
        log.info("Booking " + person + " in a seat...");
        jdbcTemplate.update("insert into BOOKINGS(FIRST_NAME) values (?)", person);
    }
};

Note that this method should be public and not private. You may want to consider putting @Transactional on the public method calling databaseChanges().

There are also advanced topics about where @Transactional should go and how it behaves, so better to get something working first and then explore this area a bit later:)

After all these are in place (dependency + transactionManager configuration + annotation), then transactions should work accordingly.

References

Spring Reference Documentation on Transactions

Spring Guide for Transactions using Spring Boot - This has sample code that you can play with