Migrations

This section is based on Granite's README

Granite doesn't have migrations built in. Instead, we leveraged the excellent work done by Juan Edi called micrate. We have integrated Micrate into the Maze CLI.

Migration scripts

Migration scripts are created in the db/migrations directory. It's recommended that the files use a timestamp as a way to keep the order of execution.

A micrate script has two sections, Up and Down. Here is an example file:

db/migrations/20171003212124_create_post.sql

-- +micrate Up
CREATE TABLE posts (
  id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  title VARCHAR(255),
  body TEXT,
  pages INT,
  published BOOL,
  created_at TIMESTAMP NULL,
  updated_at TIMESTAMP NULL
);

-- +micrate Down
DROP TABLE IF EXISTS posts;

Generators

Maze CLI provides the ability to generate migration scripts:

maze generate migration create_posts

This will generate an empty micrate script with the timestamp set in the filename:

db/migrations/20171003212124_create_post.sql

If you generate a model or scaffold, it will create a migration script that will create and drop the database table.

maze generate scaffold post name:string body:text pages:int published:bool

This will generate the migration script shown above.

Run the migrations

You can run the migrations using either:

maze db migrate

You can rollback a migration using either:

maze db rollback

Drop and Create a database

The maze db commmand also allows you to create and drop the database itself:

maze db drop create migrate

Seed the database

Sometimes you need to pre-populate your tables with data. This is common if you need an beginning administrator account or populate lookup tables that rarely change.

You can do this by creating a db/seeds.cr file

require "../config/application.cr"

user = User.new
user.email = "[e-mail]"
user.password = "password"
user.save

This example seeds.cr file creates an admin user.

You can execute the seeds using:

maze db seed