convert_enum_from_integer_to_string.rb

# MIGRATION
change_column :my_table, :status, :string

# LOGICS
module SafeEnumHelper
  def self.ensure(resource:, column:, mapping:)
    raw_status = resource.attributes_before_type_cast[column]
    is_integer = /\A[-+]?\d+\z/ === raw_status

    if is_integer
      mapping[raw_status.to_sym] if is_integer
    else
      raw_status
    end
  end
end

# USE IN MODEL
def status
  SafeEnumHelper.ensure(
    resource: self,
    column: 'status',
    mapping: {
      '0': 'draft',
      '1': 'publish',
      '2': 'trash'
      }
    )
end

enum status: { draft: 'draft', publish: 'publish', trash: 'trash' }
# enum status: [:draft, :publish, :trash]