When deleting a migration, it knows to delete every file named
"[0-9]*_#{file_name}".
# File railties/lib/rails_generator/commands.rb, line 519
def migration_template(relative_source, relative_destination, template_options = {})
migration_directory relative_destination
migration_file_name = template_options[:migration_file_name] || file_name
unless migration_exists?(migration_file_name)
puts "There is no migration named #{migration_file_name}"
return
end
existing_migrations(migration_file_name).each do |file_path|
file(relative_source, file_path, template_options)
end
end