abstract class Cql::Migration

Overview

Migrations are used to manage changes to the database schema over time. Each migration is a subclass of Migration and must implement the #up and #down methods.

The #up method is used to apply the migration, while the #down method is used to rollback the migration. Migrations are executed in their version order defined. The Migrator class is used to manage migrations and provides methods to apply, rollback, and redo migrations. The Migrator class also provides methods to list applied and pending migrations. Example Creating a new migration

class CreateUsersTable < Cql::Migration
  self.version = 1_i64

  def up
    schema.table :users do
      primary :id, Int64
      column :name, String
      column :email, String
    end
  end

  def down
    schema.drop_table :users
  end
end

Example Applying migrations

schema = Cql::Schema.build(:northwind, "sqlite3://db.sqlite3") do |s|
  s.create_table :schema_migrations do
    primary :id, Int32
    column :name, String
    column :version, Int64, index: true, unique: true
    timestamps
  end
end
migrator = Cql::Migrator.new(schema)
migrator.up

Example Rolling back migrations

migrator.down

Example Redoing migrations

migrator.redo

Example Rolling back to a specific version

migrator.down_to(1_i64)

Example Applying to a specific version

migrator.up_to(1_i64)

Example Listing applied migrations

migrator.print_applied_migrations

Example Listing pending migrations

migrator.print_pending_migrations

Example Listing rolled back migrations

migrator.print_rolled_back_migrations

Example Listing the last migration

migrator.last

Defined in:

migrations.cr

Constructors

Instance Method Summary

Constructor Detail

def self.new(schema : Schema) #

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Instance Method Detail

abstract def down #

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def schema : Schema #

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abstract def up #

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