Database Integration in Express.js

Web applications often need to store data beyond the lifespan of a single server session. While arrays and objects can store data temporarily, they do not persist across server restarts, making a database necessary for long-term data management.

A database solves this problem by providing a structured way to store, retrieve, and manipulate data. With a database, we can:

• Store and retrieve data across multiple server instances.

• Query data efficiently using indexes.

• Ensure data integrity through structured schemas.

• Scale applications to handle large amounts of data.

SQL vs. NoSQL: Choosing the right database

Databases fall into two broad categories:

• SQL (relational): These databases store data in tables with predefined schemas. Examples include MySQL and PostgreSQL. They use SQL for querying and ensure data consistency through strict relationships between tables.

• NoSQL (Non-relational): These databases store data in flexible formats like key-value pairs, documents, or graphs. Examples include MongoDB and Firebase. They allow dynamic schemas and scale horizontally to handle large amounts of data efficiently.

For this course, we use MongoDB, a NoSQL database, because it integrates well with Express.js and stores data in an easy-to-read JSON-like format.

Connecting to MongoDB using Mongoose

To interact with MongoDB in an Express.js application, we use Mongoose, an Object Data Modeling (ODM) library for MongoDB. It provides a high-level abstraction over MongoDB, making it easier to define schemas, query data, and manage relationships within a Node.js application. Unlike a raw MongoDB client, Mongoose includes features like validation, middleware, and query building, which streamline database interactions in an Express.js application.

Let’s look at the code to connect our Express application to a MongoDB database.