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我在这种特定方法中遇到了问题。我第一次保存它的方法是在 AppointmentEvent 中创建一条记录并在 Appointment 中更改已验证的变量，但它会再次创建用户记录。 

private void CreateAppointment(Employee user)
        {
            try
            {
                using (var db = new CosmeticContext())
                {
                    Appointment appointment = db.Appointment.FirstOrDefault(o => o.name == phoneNumber.name && o.surname == phoneNumber.surname && o.verified == false);
                    appointment.verified = true;
                    PhoneNumber ph = db.PhoneNumber.FirstOrDefault(o => o.name == phoneNumber.name && o.surname == phoneNumber.surname);
                    db.PhoneNumber.Remove(ph);
                    db.AppointmentEvent.Add(new AppointmentEvent
                    {
                        date = DateTime.Now,
                        Employees = user,
                        Appointments = appointment,
                        EventComment = EventComment.Save
                    });
                    db.SaveChanges();
                }
          }
            catch (System.Data.Entity.Validation.DbEntityValidationException e)
            {
                DbScript.ShowEntityErrors(e);
            }
        }

当我第二次运行它时，它会使用以前的值复制用户、约会事件和约会记录。当我通过调试器时，我看到 db.AppointmentEvent.Local 有 0 条记录，但第二次 Add 方法在 db.AppointmentEvent.Local 中创建了 2 条记录。我不明白一种 Add 方法如何添加 2 条记录。谷歌在为我展示正确的案例方面没有帮助，但 using 块不应该正确处理所有内容吗？

以下是一些包含此处使用的对象的附加类：

public class Employee
{
    [Key]
    public int employeeId { get; set; }
    [Required, MaxLength(25), MinLength(4)]
    public string userName { get; set; }
    [Required, MaxLength(25), MinLength(4)]
    public string firstName { get; set; }
    [Required, MaxLength(25), MinLength(4)]
    public string lastName { get; set; }
    [Required, MaxLength(100), MinLength(20)]
    public string password { get; set; }
    [Required]
    public EmployeeType EmployeeType { get; set; }
    public virtual List<PhoneNumber> PhoneNumbers { get; set; }
    public virtual List<AppointmentEvent> AppointmentEvents { get; set; }
}

public class AppointmentEvent
{
    public int appointmentEventId { get; set; }
    [Required]
    public DateTime date { get; set; }
    [Required]
    public virtual Employee Employees { get; set; }
    [Required]
    public virtual Appointment Appointments { get; set; }
    [Required]
    public EventComment EventComment { get; set; }
}

public class Appointment
{
    [Key]
    public int appointmentId { get; set; }
    [Required, MaxLength(20)]
    public string name { get; set; }
    [Required, MaxLength(30)]
    public string surname { get; set; }
    [Required, MaxLength(20), Phone]
    public string phone { get; set; }
    [Required]
    public DateTime date { get; set; }
    [Required]
    public ServiceType ServiceType { get; set; }
    [Required]
    public bool verified { get; set; }
    public virtual List<AppointmentEvent> AppointmentEvents { get; set; }
}

编辑：忘了告诉我正在创建一个 Windows 窗体应用程序和更多代码，它显示了用户部分。：这是 Form nr2 。：（我的记录有问题）

    public partial class CallCenter : Form
    {
        Employee employee;
        static ListTime listTime = new ListTime();
        Button pushedButton = new Button();

        public CallCenter(Employee loginEmployee)
        {

            employee = loginEmployee;

            InitializeComponent();
            tableLayoutPanel2.CellPaint += tableLayoutPanel1_CellPaint;
            GeneratedServiceTypeComboBox.DataSource = Enum.GetValues(typeof(ServiceType));
            textBox1.Text = DateTime.Now.AddDays(1).Date.ToString("dd.MM.yyyy");
            textBox2.Text = DateTime.Now.AddDays(2).Date.ToString("dd.MM.yyyy");
            RefreshAppointmentAvailabilityTable();
        }

   private void SaveButton_Click(object sender, EventArgs e)
        {
            try
            {
                GenerateButton.Enabled = true;
                SaveButton.Enabled = false;
                this.NameBox.Text = string.Empty;
                SurnameBox.Text = string.Empty;
                PhoneBox.Text = string.Empty;
                GeneratedNameBox.Text = string.Empty;
                GeneratedSurnameBox.Text = string.Empty;
                GeneratedPhoneBox.Text = string.Empty;
                pushedButton.BackColor = Color.LightGreen;
                ChangeAppointmentAvailabilityButtonsStatus(false);
                CreateAppointment(employee);
            }
            catch (Exception f)
            { MessageBox.Show(f.ToString()); }

        }
    ...
    }

这是来自form1：（登录屏幕）

    private void LoginButton_Click(object sender, EventArgs e)
    {
        using (var db = new CosmeticContext())
        {  
            bool verify = false;
            Employee employee = db.Employee.FirstOrDefault(o => o.userName == UserNameBox.Text);
            if (employee == null)
                MessageBox.Show("Sads lietotajs nav atrasts datubaze", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Error);
            else
            {
                verify = PasswordAlgorithm.DoesPasswordMatch(employee.password, PasswordBox.Text);
                if (verify)
                    if (employee.EmployeeType == EmployeeType.Seller)
                    {
                        CallCenter form1 = new CallCenter(employee);
                        form1.Show();
                        this.Hide();
                    }
            }
        }
    }
4

1 回答 1

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您的用户是否被 EntityFramework 上下文跟踪？如果它没有被跟踪，EF 不会知道任何更好的，并且很乐意通过添加新用户而不是将约会与现有用户相关联来建立关联。我怀疑这就是这里发生的事情：

ObjectContext.AddObject和ObjectSet.AddObject：AddObject 方法用于添加数据库中不存在的新创建的对象。该实体将获得一个自动生成的临时 EntityKey，其 EntityState 将设置为已添加。当调用 SaveChanges 时，EF 将清楚该实体需要插入到数据库中。

ObjectContext.Attach和ObjectSet.Attach：另一方面，Attach 用于数据库中已经存在的实体。不是将 EntityState 设置为已添加，而是 Attach 会导致未更改的 EntityState，这意味着它在附加到上下文后没有更改。假定您附加的对象存在于数据库中。如果在附加对象后对其进行修改，则在调用 SaveChanges 时，EntityKey 的值用于通过在 db 表中查找其匹配 ID 来更新（或删除）相应的行。

于 2013-10-20T18:44:42.470 回答