Building a Persistent Data Layer with Java, React, and Spring Boot
In the first article of this series, we developed a simple Todo app that integrated a React front end with a Java back end using Spring Boot. We explored how to define JSON API endpoints and interact with them using React components and JavaScript’s Fetch API. However, our implementation so far only stored to-do items in memory, meaning the data was lost whenever the server restarted. In this article, we’ll enhance our back end by introducing MongoDB and Spring Data to enable persistent data storage.
Developing the Data Layer with MongoDB and Spring Data
To make our application more robust, we need to introduce a proper database layer. MongoDB is a popular NoSQL database that fits well with modern web applications, and Spring Data provides an efficient way to interact with it in a Spring Boot environment. For this setup, we’ll use a locally installed MongoDB instance, which is straightforward to set up following the official MongoDB documentation. While this demo will use a local instance without authentication, in a real-world scenario, we would implement proper security measures. The MongoDB driver will allow our application to connect to the database, and Spring Data will streamline database operations using its repository abstraction.
Adding Persistence to the Model Class
Our application already has a TodoItem model class that represents a to-do item. To enable database persistence, we’ll annotate this class with Spring Data’s MongoDB-specific annotations. By marking the class as a @Document and specifying an @Id field, we tell Spring Data to treat it as a MongoDB document. This approach abstracts away much of the complexity, allowing us to perform CRUD operations on our to-do items with minimal boilerplate code.
The Path Forward
With our database layer in place, the next steps will involve wiring up the repository layer to our service and controller layers, ensuring our API endpoints can create, retrieve, update, and delete to-do items in MongoDB. We’ll also refine our front-end logic to reflect these changes, ensuring our React app properly interacts with the persistent back end. This upgrade brings us closer to a fully functional, real-world application that maintains data even after server restarts.