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module 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_number method.

Attributes

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

Public instance methods

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

Source code GitHub 
# 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

migration_template(source, destination, config = {})

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

The migration number, 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 GitHub 
# 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)

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

  file = create_migration numbered_destination, nil, config do
    ERB.new(::File.binread(source), trim_mode: "-", eoutvar: "@output_buffer").result(binding)
  end
  Rails::Generators.add_generated_file(file)
end

set_migration_assigns!(destination)

Source code GitHub 
# 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

Definition files