Book Image

Supercharging Node.js Applications with Sequelize

By : Daniel Durante
4 (1)
Book Image

Supercharging Node.js Applications with Sequelize

4 (1)
By: Daniel Durante

Overview of this book

Continuous changes in business requirements can make it difficult for programmers to organize business logic into database models, which turns out to be an expensive operation as changes to the database may result in errors and incongruity within applications. Supercharging Node.js Applications with Sequelize helps you get to grips with Sequelize, a reliable ORM that enables you to alleviate these issues in your database and applications. With Sequelize, you'll no longer need to store information in flat files or memory. This book takes a hands-on approach to implementation and associated methodologies for your database that will have you up and running in no time. You'll learn how to configure Sequelize for your Node.js application properly, develop a better sense of understanding of how this ORM works, and find out how to manage your database from Node.js using Sequelize. Finally, you'll be able to use Sequelize as the database driver for building your application from scratch. By the end of this Node.js book, you'll be able to configure, build, store, retrieve, validate, and associate your data from a database to a Node.js application.
Table of Contents (16 chapters)
1
Part 1 – Installation, Configuration, and the Basics
4
Part 2 – Validating, Customizing, and Associating Your Data
10
Part 3 – Advanced Queries, Using Adapters, and Logging Queries

Querying associations with eager loading and lazy loading

Sequelize offers two different methods of querying associations depending on how you wish to query the data: eager loading and lazy loading. With eager loading, you would load all of the associated data at once. The lazy loading method will load the associations per query as they are called upon from the code. It is easier to explain eager loading than lazy loading but to see the benefits of eager loading, we will need to go over lazy loading first.

Note

You may have heard of the “N+1 select problem” with other ORM frameworks; this is referring to the lazy loading method (although, not mutually exclusive) and how selecting an association per row could be hazardous to your application’s performance.

Lazy loading

Sequelize tries to make no presumptions about your intent and will initially select only the model’s data. We will need to explicitly call the associations if we want to transverse...