How to Upgrade Spring Boot for MongoDB Transaction Support

Background

The company currently uses Spring Boot 1.5.12.RELEASE, which does not support MongoDB transaction management. As business complexity grows, ensuring data consistency and atomicity becomes critical.

Why Upgrade Spring Boot

Data consistency: Newer Spring Boot versions support MongoDB transactions, guaranteeing atomic operations and improving system stability.

Technical alignment: Keeping the stack up‑to‑date ensures compatibility with other components and provides performance improvements.

Developer efficiency: Simplified transaction handling reduces code complexity, boosts development speed, and lowers maintenance costs.

Version Selection

Requirements for MongoDB transaction support:

Mongodb 4.0 replica set or 4.2 sharded cluster (required)

spring.data.mongodb version 2.1+ (required)

Spring Boot version 2.1+ (required)

Since the project already uses MongoDB 4.0+, only Spring Boot and spring.data.mongodb need upgrading.

Chosen versions:

spring.data.mongodb: 2.1.15.RELEASE

springboot: 2.1.12.RELEASE

Feature Highlights

Default Dynamic Proxy Strategy

Uses CGLIB proxies by default, including AOP. To switch to interface‑based proxies, set spring.aop.proxy-target-class=false.

WebMvcConfigurerAdapter Deprecated

The abstract class WebMvcConfigurerAdapter is obsolete; replace it with WebMvcConfigurer.

public class MyWebMvcConfigurerAdapter implements WebMvcConfigurer {
    // ...
}

Relational Database

The default connection pool changes from Tomcat to HikariCP (performance: HikariCP > Druid > tomcat‑jdbc > dbcp > c3p0). Use spring.datasource.type to enforce Hikari.

Redis

When using spring-boot-starter-redis, Lettuce replaces Jedis as the default driver, though Jedis remains supported and can be swapped via dependency exclusion.

Server‑Specific Properties

Several servlet‑specific settings have moved to server.servlet properties.

Dependency Versions

Elasticsearch 5.6

Gradle 4

Hibernate 5.2

Jetty 9.4

Spring Framework 5

Spring Security 5

Tomcat 8.5

More Features

https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.0-Migration-Guide

https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.1-Release-Notes

Upgrade Steps

Step 1 – Modify pom.xml

Update the parent version:

<parent>
    <groupId>suishen-webx</groupId>
    <artifactId>suishen-webx-parent</artifactId>
    <version>2.0-SNAPSHOT</version>
</parent>

Confirm dependency versions in the project (see screenshot).

Step 2 – Enable Transactions

Add @EnableTransactionManagement to the main application class:

@EnableTransactionManagement
public class MainApplication extends SuishenWebxApplication {
}

Configure a MongoDB transaction manager either via XML:

<!-- Configure MongoDB transaction manager -->
<bean id="transactionManager" class="org.springframework.data.mongodb.MongoTransactionManager">
    <constructor-arg name="dbFactory" ref="mongoDbFactory"/>
</bean>

or via Java configuration:

@Configuration
public class TransactionConfig {
    @Bean
    public MongoTransactionManager transactionManager(MongoDatabaseFactory factory){
        return new MongoTransactionManager(factory);
    }
}

Step 3 – Adjust MongoDB Password

spring.data.mongodb 2.1.15.RELEASE decodes passwords with URLDecoder.decode, so percent signs (%) must be escaped as %25. Verify the process using MongoCredentialPropertyEditor.extractUserNameAndPassword.

Using Transactions

Declarative Transaction Handling

Annotate methods with @Transactional:

@SuishenLog(logName = "Add Strategy")
public StrategyVo addStrategy(StrategyAddReq addReq) {
    // business logic
}

@SuishenLog(logName = "Add Strategy Transaction")
@Transactional(propagation = Propagation.REQUIRED, rollbackFor = Exception.class)
public StrategyVo addStrategyTest(StrategyAddReq addReq) {
    return addStrategy(addReq);
}

Transaction Propagation Behaviors

PROPAGATION_REQUIRED – default; joins existing transaction or creates a new one.

PROPAGATION_SUPPORTS – joins if present, otherwise executes non‑transactionally.

PROPAGATION_MANDATORY – must have an existing transaction, else throws.

PROPAGATION_REQUIRES_NEW – suspends current transaction and starts a new one.

PROPAGATION_NOT_SUPPORTED – suspends any transaction and runs non‑transactionally.

PROPAGATION_NEVER – throws if a transaction exists.

PROPAGATION_NESTED – uses savepoints for nested transactions.

Programmatic Transaction Handling

@SuishenLog(logName = "Add Strategy Transaction Test")
@Transactional(propagation = Propagation.REQUIRED, rollbackFor = Exception.class)
public StrategyVo addStrategyTest2(StrategyAddReq addReq) {
    return addStrategy(addReq);
}

TransactionTemplate txTemplate = new TransactionTemplate(mongoTransactionManager);
return txTemplate.execute(new TransactionCallback<StrategyVo>() {
    @Override
    public StrategyVo doInTransaction(TransactionStatus status) {
        try {
            return addStrategy(addReq);
        } catch (Exception e) {
            status.setRollbackOnly();
        }
        return null;
    }
});

Data Verification

Calling addStrategy succeeds for Strategy but fails for StrategyLog.

Calling addStrategyTest rolls back both inserts.

Calling addStrategyTest2 also rolls back both inserts.

org.springframework.transaction.UnexpectedRollbackException: Transaction rolled back because it has been marked as rollback-only
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.processRollback(...)
    ...

Author: Sun Jingliang, Senior Backend Engineer.