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

Managed and unmanaged transactions

Managed transactions are typically easier for developers with previous object-relational mapping (ORM) experience, and unmanaged transactions may be more familiar to developers who write Structured Query Language (SQL) directly. Unmanaged transactions are explicit by design, but managed transactions have some implicit behaviors for state management such as automatically creating a transaction instance and calling your callback method with that transaction.

Let’s look at the steps for creating unmanaged transactions, as follows:

  1. We would start by creating a transaction instance, like so:
    const tx = await sequelize.transaction();
  2. Next, we will want to wrap our queries in a try block. For this example, we will increment and decrement two account balances by 100 using the same transaction instance, like so:
    try {
        const amount = 100;
        await Account.increment(
         ...