Sequelize CLI Quick Reference

Reference

February 22, 2019

I found this video to be very helpful for getting a start with using Sequelize CLI. I think I watched it at least 20 times to view and review the information. So for posterity’s sake and to avoid shuttling through this video again in the future, here is my summary:

Sequelize Migrations are useful because they let you change the structure of your database tables after they have already been created, even if they contain data. The changes are incremental and reversible (though it’s important to note, dropping existing data during a migration is not reversible).

A migration must contain an up function (the change you want to make) and a down function (the code to undo the same change). The migrations make use of Sequelize’s QueryInterface API to do things like bulkInsert, addColumn, or changeColumn, etc.

Sequelize CLI Commands

Commands:
  sequelize db:migrate                        Run pending migrations
  sequelize db:migrate:schema:timestamps:add  Update migration table to have timestamps
  sequelize db:migrate:status                 List the status of all migrations
  sequelize db:migrate:undo                   Reverts a migration
  sequelize db:migrate:undo:all               Revert all migrations ran
  sequelize db:seed:undo                      Deletes data from the database
  sequelize db:seed:all                       Run every seeder
  sequelize db:seed --seed XXXX-file.js       Run specified seeder
  sequelize db:seed:undo:all                  Deletes data from the database
  sequelize db:seed:undo --seed XXXX-file.js  Deletes specified seeder
  sequelize db:create                         Create database specified by configuration
  sequelize db:drop                           Drop database specified by configuration
  sequelize init                              Initializes project
  sequelize init:config                       Initializes configuration
  sequelize init:migrations                   Initializes migrations
  sequelize init:models                       Initializes models
  sequelize init:seeders                      Initializes seeders
  sequelize migration:generate                Generates a new migration file [aliases: migration:create]
  sequelize model:generate                    Generates a model and its migration [aliases: model:create]
  sequelize seed:generate                     Generates a new seed file [aliases: seed:create]

Options:
  --help     Show help [boolean]
  --version  Show version number

Setting Up a Project Using Sequelize CLI With Migrations

I wrote up a detailed step-by-step in this post. The short version is as follows…

Creating a Model

A model and create migration file can be created with one command:

sequelize model:generate --name User --attributes firstName:string,lastName:string,email:string,registered:boolean,age:integer

This command creates the basic structure of each file. Add any modifications (such as validations, constraints, etc.) to both the model file and the migration file if necessary.

Add associations to the model file.

Run the db:migrate command to persist the model(s) to the database, and db:migrate:undo to reverse the changes.

Modify A Table With A Migration

Create a new migration with a similar command to:

sequelize migration:create --name add-title-to-todos

The file will be an empty structure and you will need to fill in the migration instructions. Here is an example of a migration that will add a new column to the data table:

'use strict';

module.exports = {
  up: function (queryInterface, Sequelize) {
   queryInterface.addColumn('Todos', 'title', {
    type: Sequelize.STRING
   });
  },

  down: function (queryInterface, Sequelize) {
    queryInterface.removeColumn('Todos', 'title');
  }
};

Don’t forget to also update the model file manually. Sequelize CLI does not automatically update the model when a structure-changing migration is run against the model.

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