Sequelize Introduction

What is Sequelize ?

Sequelize is a promise-based Node.js ORM for Postgres, MySQL, MariaDB, SQLite, and Microsoft SQL Server. Its features are solid transaction support, relations, eager and lazy loading, read replication and many more.

Features of Sequelize:

  • Sequelize is a third-party package to be precise its an Object-Relational Mapping Library(ORM)..
  • Standardization ORMs usually have a single schema definition in the code. This makes it very clear what the schema is, and very simple to change it.
  • No need to learn SQL – queries are written in plain JavaScript.

Here are some key features and concepts of Sequelize:

1. Models: Define the structure of your database tables and their relationships using JavaScript classes or objects. Each model corresponds to a table in your database.

2. Associations: Sequelize supports defining relationships between models, such as one-to-one, one-to-many, and many-to-many. This helps in handling related data more efficiently.

3. Migrations: Manage and version-control changes to your database schema. Migrations allow you to keep track of changes and apply them in a systematic way.

4. Seeding: Populate your database with initial data or test data using seed files.

5. Queries: Sequelize provides a range of methods for querying the database, including find, create, update, and delete operations, as well as more complex queries with conditions and joins.

6. Transactions: Manage transactions to ensure that a series of operations are completed successfully before committing changes to the database.

7. Validation: Validate data before it gets saved to the database. Sequelize supports built-in and custom validators for model attributes.

8. Hooks: Execute custom logic before or after certain operations (e.g., before saving a record or after deleting one).

If you’re working with Sequelize, you’ll typically start by setting up your database connection, defining your models, and then using those models to interact with your database.

Do you have a specific question or need help with something particular in Sequelize?