Question

I have the following code which connected to my database, and checks if an email address exists in a Table, if it does, it will delete it, if it doesn’t, it will add it.

But neither options work. I get the same error for both actions:

The object cannot be deleted because it was not found in the
ObjectStateManager.

The code:

protected OEntities database = new OEntities();

public string NewsletterSubscriptionValidation(string emailAddress)
{
    string validationMessage = "";
    Newsletter newsletter = new Newsletter();

    var identifier = database.Newsletters.Select(
        id => id.EmailAddress);

    if (identifier == null)
    {
        newsletter.EmailAddress = emailAddress;
        newsletter.Subscribed = true;

        database.Newsletters.AddObject(newsletter);
        database.SaveChanges();

        validationMessage = "You are now subscribed to our periodic Newsletter.";
    }
    else
    {
        newsletter.EmailAddress = emailAddress;
        newsletter.Subscribed = false;


        database.DeleteObject(newsletter);
        database.SaveChanges();

        validationMessage = "You have been unsubscribed from our periodic Newsletter.";
    }

    return validationMessage;
}

Am I even adding to/deleting from the Database the right way, here?

Solution

---

protected OEntities database = new OEntities();

public string NewsletterSubscriptionValidation(string emailAddress)
{
    string validationMessage = "";
    Newsletter newsletter = database.Newsletters.FirstOrDefault(
        nl => nl.EmailAddress == emailAddress);

    if (newsletter == null)
    {
        newsletter = new Newsletter();

        newsletter.EmailAddress = emailAddress;
        newsletter.Subscribed = true;

        database.AddToNewsletters(newsletter);
        //database.Newsletters.AddObject(newsletter);
        database.SaveChanges();

        validationMessage = "You are now subscribed to our periodic Newsletter.";
    }
    else
    {
        newsletter.EmailAddress = emailAddress;
        newsletter.Subscribed = true;

        database.AddToNewsletters(newsletter);
        //database.Newsletters.AddObject(newsletter);
        database.SaveChanges();

        validationMessage = "You have been unsubscribed from our periodi Newsletter.";
    }

    return validationMessage;
}

Answer 1

You need to attach before you delete

    database.Attach(newsletter); 
    database.DeleteObject(newsletter); 
    database.SaveChanges(); 

but you probably want to select the existing item more like this

Newsletter newsletter = database.Newsletters.FirstOrDefault(nl => nl.EmailAddress == emailAddress);
if (newsletter == null)
{
    newsletter = new Newsletter();
    ...
}
else
{
    database.Attach(newsletter); 
    database.DeleteObject(newsletter); 
    database.SaveChanges(); 
}