Rails::Generators::Migration

Holds common methods for migrations. It assumes that migrations have the [0-9]*_name format and can be used by other frameworks (like Sequel) just by implementing the next migration version method.

Methods

create_migration
migration_template
set_migration_assigns!

Attributes

[R]	migration_class_name
[R]	migration_file_name
[R]	migration_number

Instance Public methods

create_migration(destination, data, config = {}, &block)

📝 Source code

# File railties/lib/rails/generators/migration.rb, line 35
      def create_migration(destination, data, config = {}, &block)
        action Rails::Generators::Actions::CreateMigration.new(self, destination, block || data.to_s, config)
      end

🔎 See on GitHub

migration_template(source, destination, config = {})

Creates a migration template at the given destination. The difference to the default template method is that the migration version is appended to the destination file name.

The migration version, migration file name, migration class name are available as instance variables in the template to be rendered.

migration_template "migration.rb", "db/migrate/add_foo_to_bar.rb"

📝 Source code

# File railties/lib/rails/generators/migration.rb, line 56
      def migration_template(source, destination, config = {})
        source = File.expand_path(find_in_source_paths(source.to_s))

        set_migration_assigns!(destination)
        context = instance_eval("binding")

        dir, base = File.split(destination)
        numbered_destination = File.join(dir, ["%migration_number%", base].join("_"))

        file = create_migration numbered_destination, nil, config do
          if ERB.instance_method(:initialize).parameters.assoc(:key) # Ruby 2.6+
            ERB.new(::File.binread(source), trim_mode: "-", eoutvar: "@output_buffer").result(context)
          else
            ERB.new(::File.binread(source), nil, "-", "@output_buffer").result(context)
          end
        end
        Rails::Generators.add_generated_file(file)
      end

🔎 See on GitHub

set_migration_assigns!(destination)

📝 Source code

# File railties/lib/rails/generators/migration.rb, line 39
      def set_migration_assigns!(destination)
        destination = File.expand_path(destination, destination_root)

        migration_dir = File.dirname(destination)
        @migration_number     = self.class.next_migration_number(migration_dir)
        @migration_file_name  = File.basename(destination, ".rb")
        @migration_class_name = @migration_file_name.camelize
      end

🔎 See on GitHub