How to auto generate migrations with Sequelize CLI from Sequelize models?

Solution 1:

If you don't want to recreate your model from scratch, you can manually generate a migration file using the following CLI command:

sequelize migration:generate --name [name_of_your_migration]

This will generate a blank skeleton migration file. While it doesn't copy your model structure over to the file, I do find it easier and cleaner than regenerating everything. Note: make sure to run the command from the containing directory of your migrations directory; otherwise the CLI will generate a new migration dir for you

Solution 2:

You cannot create migration scripts for existing models.

Resources:

Tutorial video on migrations.

If going the classic way, you'll have to recreate the models via the CLI:

sequelize model:create --name MyUser --attributes first_name:string,last_name:string,bio:text

It will generate these files:

models/myuser.js:

"use strict";
module.exports = function(sequelize, DataTypes) {
  var MyUser = sequelize.define("MyUser", {
    first_name: DataTypes.STRING,
    last_name: DataTypes.STRING,
    bio: DataTypes.TEXT
  }, {
    classMethods: {
      associate: function(models) {
        // associations can be defined here
      }
    }
  });
  return MyUser;
};

migrations/20150210104840-create-my-user.js:

"use strict";
module.exports = {
  up: function(migration, DataTypes, done) {
    migration.createTable("MyUsers", {
      id: {
        allowNull: false,
        autoIncrement: true,
        primaryKey: true,
        type: DataTypes.INTEGER
      },
      first_name: {
        type: DataTypes.STRING
      },
      last_name: {
        type: DataTypes.STRING
      },
      bio: {
        type: DataTypes.TEXT
      },
      createdAt: {
        allowNull: false,
        type: DataTypes.DATE
      },
      updatedAt: {
        allowNull: false,
        type: DataTypes.DATE
      }
    }).done(done);
  },
  down: function(migration, DataTypes, done) {
    migration.dropTable("MyUsers").done(done);
  }
};

Solution 3:

It's 2020 and many of these answers no longer apply to the Sequelize v4/v5/v6 ecosystem.

The one good answer says to use sequelize-auto-migrations, but probably is not prescriptive enough to use in your project. So here's a bit more color...

Setup

My team uses a fork of sequelize-auto-migrations because the original repo is has not been merged a few critical PRs. #56 #57 #58 #59

$ yarn add github:scimonster/sequelize-auto-migrations#a063aa6535a3f580623581bf866cef2d609531ba

Edit package.json:

"scripts": {
  ...
  "db:makemigrations": "./node_modules/sequelize-auto-migrations/bin/makemigration.js",
  ...
}

Process

Note: Make sure you’re using git (or some source control) and database backups so that you can undo these changes if something goes really bad.

Delete all old migrations if any exist.
Turn off .sync()
Create a mega-migration that migrates everything in your current models (yarn db:makemigrations --name "mega-migration").
Commit your 01-mega-migration.js and the _current.json that is generated.
if you've previously run .sync() or hand-written migrations, you need to “Fake” that mega-migration by inserting the name of it into your SequelizeMeta table. INSERT INTO SequelizeMeta Values ('01-mega-migration.js').
Now you should be able to use this as normal…
Make changes to your models (add/remove columns, change constraints)
Run $ yarn db:makemigrations --name whatever
Commit your 02-whatever.js migration and the changes to _current.json, and _current.bak.json.
Run your migration through the normal sequelize-cli: $ yarn sequelize db:migrate.
Repeat 7-10 as necessary

Known Gotchas

Renaming a column will turn into a pair of removeColumn and addColumn. This will lose data in production. You will need to modify the up and down actions to use renameColumn instead.

For those who confused how to use renameColumn, the snippet would look like this. (switch "column_name_before" and "column_name_after" for the rollbackCommands)

{
    fn: "renameColumn",
    params: [
        "table_name",
        "column_name_before",
        "column_name_after",
        {
            transaction: transaction
        }
    ]
}

If you have a lot of migrations, the down action may not perfectly remove items in an order consistent way.
The maintainer of this library does not actively check it. So if it doesn't work for you out of the box, you will need to find a different community fork or another solution.

Solution 4:

You can now use the npm package sequelize-auto-migrations to automatically generate a migrations file. https://www.npmjs.com/package/sequelize-auto-migrations

Using sequelize-cli, initialize your project with

sequelize init

Create your models and put them in your models folder.

Install sequelize-auto-migrations:

npm install sequelize-auto-migrations

Create an initial migration file with

node ./node_modules/sequelize-auto-migrations/bin/makemigration --name <initial_migration_name>

Run your migration:

node ./node_modules/sequelize-auto-migrations/bin/runmigration

You can also automatically generate your models from an existing database, but that is beyond the scope of the question.

Solution 5:

I created a small working "migration file generator". It creates files which are working perfectly fine using sequelize db:migrate - even with foreign keys!

You can find it here: https://gist.github.com/manuelbieh/ae3b028286db10770c81

I tested it in an application with 12 different models covering:

STRING, TEXT, ENUM, INTEGER, BOOLEAN, FLOAT as DataTypes
Foreign key constraints (even reciprocal (user belongsTo team, team belongsTo user as owner))
Indexes with name, method and unique properties