Question

I need help to refactor some parts of this code example from where if (_obj is Application) so this will be generic.

public override void Body(object _obj, object _objInPreviousState)
        {

            if (_obj != null)
            {
                string Message = "";
                string Subject = "";
                if (_objInPreviousState == null)
                {
                    var emailParams = this.Param as Dictionary<string, string>;
                    if (emailParams != null)
                    {
                        Message = emailParams["Message"];
                        Subject = emailParams["Subject"];
                    }
                }
                var emails = userRepository().GetForRoles("RM").Select(c => c.Email);
                if (_obj is Application)
                {
                    var app = (Application)_obj;
                    var appInPreviousState = _objInPreviousState as Application;
                    if (appInPreviousState == null)
                    {
                        emailService().SendEmails("[e-mail]", emails.ToArray(), Message, Subject);
                    }
                    else if (app.ApplicationStatus != appInPreviousState.ApplicationStatus)
                    {
                        emailService().SendEmails("[e-mail]", emails.ToArray(), "Application: " + app.ID + " changed decision status: " + Enum.GetName(typeof(AppStatus), app.ApplicationStatus), "Check following application: " + app.ID);
                    }
                }
                else if (_obj is Product)
                {
                    var product = (Product)_obj;
                    var prodInPreviousState = _objInPreviousState as Product;
                    if (prodInPreviousState == null)
                    {
                        emailService().SendEmails("[e-mail]", emails.ToArray(), Message, Subject);
                    }
                    else if (product.ProductStatusType != prodInPreviousState.ProductStatusType)
                    {
                        emailService().SendEmails("[e-mail]", emails.ToArray(), "Product: " + product.ID + " for application " + product.ApplicationID + " changed decision status: " + Enum.GetName(typeof(AppStatus), product.ProductStatusType), "Check following application: " + product.ApplicationID);
                    }
                }

                else if (_obj is CES)
                {
                    var ces = (CES)_obj;
                    var cesInPreviousState = _objInPreviousState as CES;
                    if (cesInPreviousState == null)
                    {
                        emailService().SendEmails("[e-mail]", emails.ToArray(), Message, Subject);
                    }
                    else if (ces.Status != cesInPreviousState.Status)
                    {
                        emailService().SendEmails("[e-mail]", emails.ToArray(), "CES for application " + ces.ApplicationID + " changed decision status: " + Enum.GetName(typeof(CesStatuses), ces.Status), "Check following application: " + ces.ApplicationID);
                    }
                }
                else if (_obj is Comment)
                {
                    var comment = (Comment)_obj;
                    emailService().SendEmails("[e-mail]", emails.ToArray(), "Comment for the following application: " + comment.ApplicationID + " with message: " + comment.Message + " on date: " + comment.CreatedDate, "Comment for the following application: " + comment.ApplicationID);
                }
                mLog.InfoLine("Sendet Email");
            }

        }

Answer 1

You should probably use some interfaces, I’ve not given you the full code but a pattern to follow.

interface IStatusItem
{
   void SendEmails(EmailService service);
}

public class Product : IStatusItem
{
   public void SendEmails(EmailService service)
   {
      // Send Email
   }
}

public class Application : IStatusItem
{
   public void SendEmails(EmailService service)
   {
      // Send Email
   }
}

Then your main code doesn’t need all the if blocks. It just calls through to the implementation on the instance of the IStatusItem. Obviously you need to add the previous state in there.

override void Body(object _obj, object _objInPreviousState)
{
   IStatusItem sItem = obj as IStatusItem;
   if(sItem != null)
      sItem.SendEmails(emailService());
}