Introduction When I first encountered design patterns, back when I was still a student, I failed to immediately see how useful they are in software design. With experience came the wisdom and nowadays I quite enjoy implementing these blueprints whenever I have to solve particular design problem. …

Send emails with dynamic HTML content using FreeMarker template engine — Introduction In programming, events are actions that are handled by the software. Events can be triggered in different ways, for example a user clicking a button or a system itself, could trigger an event. The main point is, application needs to listen for such activities, or a particular event, and then…

Validate Input in Spring Boot — Introduction When I was first starting out my career as a developer, I often saw annotations @Validated and @Valid applied on the method parameters in controllers. Some people used @Validated, while others preferred @Valid. I was often confused which annotation to use and when. In this article I hope to explain…

Implement search and pagination in a Spring Boot app using MongoTemplate — MongoTemplate class provides us features for interacting with the database and offers operations to create, update, delete, and query MongoDB documents in a thread-safe way. The MongoTemplate class implements the interface MongoOperations. You can find methods like find, findAndModify, findAndReplace, findOne, insert, remove, save, update etc… MongoOperations has fluent APIs…

The Spring Framework is a popular Java-based application development framework that provides a comprehensive infrastructure support for developing applications in Java. In Spring, the @Controller and @RestController annotations are used to mark a class as a request handling component. …

Publish and consume messages with Spring Cloud Stream and Apache Kafka message broker — Introduction Event driven architecture requires forethought, creating the scaffolding in order to integrate popular event streaming platforms can become complicated. Spring Cloud Stream is a framework for message-driven microservice applications and it provides binder implementations for various message brokers, RabbitMQ, Apache Kafka, Kafka Streams, Amazon Kinesis, etc. …

Speed up your development and get rid of boilerplate code — If you are working as a developer, you are already aware that speed is increasingly important. You have deadlines, sprints need to be finished, requirements change and you are under pressure to produce quality code as fast as possible. In that case, this article might not be for you, since…

Transparently keep track of who created or changed an entity and when the change happened — Spring Data provides support to transparently keep track of who created or changed an entity and when the change happened. The auditing facility allows administrators and users to track system activity with multiple users and applications. To benefit from that functionality, you have to equip your entity classes with auditing…

Configure automatic rollback for checked exceptions — Recently, while I was working on a project I had a strange “bug” (what I thought at first) happen. Apparently, one of my transactions did not automatically rollback after exception was thrown. My whole point of even using @Transactional was to exploit that lovely benefit of having things rollbacked automatically…