redmine-workflow-engine/app/models/workflow_step_assignee.rb

class WorkflowStepAssignee < ActiveRecord::Base
  belongs_to :workflow_step

  validates :workflow_step_id, presence: true
  validates :assignee_type, presence: true, inclusion: { in: %w[user role_group department] }
  validates :assignee_id, presence: true
  validates :assignee_id, uniqueness: { scope: [:workflow_step_id, :assignee_type] }

  def assignee
    case assignee_type
    when 'user'
      User.find_by(id: assignee_id)
    when 'role_group'
      RoleGroup.find_by(id: assignee_id)
    when 'department'
      Department.find_by(id: assignee_id)
    end
  end

  def assignee_name
    obj = assignee
    return '(삭제됨)' unless obj

    case assignee_type
    when 'user'
      obj.name
    when 'role_group'
      "#{obj.name} (역할그룹)"
    when 'department'
      "#{obj.name} (부서)"
    end
  end

  def type_label
    case assignee_type
    when 'user' then '사용자'
    when 'role_group' then '역할 그룹'
    when 'department' then '부서'
    end
  end
end