EF6 SQLException:违反主键约束…重复的键值为(0)

我知道SQL,但我对ORM非常陌生,在2017年和2017年使用EntityFramework 6.2.0在沙箱中玩游戏。 我认为框架应该使我能够或多或少地像使用POCO对象那样编写代码,而不必处理主键/外键。 当我调用下面的code context.savechanges()时,这些更改就保存在数据库中; 我对EF6及其文档还不了解什么?

我用一个外键和一个1:N关系创建了两个表Person和WorkingHours。

  CREATE TABLE [dbo].[Person](
    [FirstName] [nvarchar](100) NOT NULL,
    [LastName] [nvarchar](100) NOT NULL,
    [BirthDate] [date] NULL,
    [Id] [int] IDENTITY(1,1) NOT NULL,
 CONSTRAINT [PK_Person] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

CREATE TABLE [dbo].[WorkingHours](
  [Id] [int] NOT NULL,
  [PersonId] [int] NOT NULL,
  [Date] [date] NOT NULL,
  [Start] [time](7) NOT NULL,
  [Hours] [real] NOT NULL,
 CONSTRAINT [PK_WorkingHours] PRIMARY KEY CLUSTERED 
(
  [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

我从数据库创建了模型。

我尝试创建两个人条目,每个条目都有一个工作时间条目,并将其立即保存到数据库中。 代码如下:

     static void Main(string[] args)
    {
        using(var context = new EntityFrameworkTrialEntities2())
        {
             // Inserting entries
            var person1 = new Person() { FirstName = "Al", LastName = "Curie", BirthDate = new DateTime(1867, 11, 7) };
            var person2 = new Person() { FirstName = "Al", LastName = "Capone", BirthDate = new DateTime(1899, 1, 7) };
            context.Person.Add(person1);
            context.Person.Add(person2);

            var workingHour1 = new WorkingHour() { Date = new DateTime(1887, 8, 18), Start = new TimeSpan(6, 35, 33), Hours = 4.3F };
            var workingHour2 = new WorkingHour() { Date = new DateTime(1919, 9, 19), Start = new TimeSpan(10, 23, 56), Hours = 3.2F };
            person2.WorkingHours.Add(workingHour1); 
            person1.WorkingHours.Add(workingHour2); 

            context.WorkingHours.Add(workingHour1);
            context.WorkingHours.Add(workingHour2);
            context.SaveChanges(); // <-- place of exeception !!!!!!!!!!!!!!!!!!!!

            // (next step as EF6 trial: here the previously intentionally mixed relationships between person1/2 and workingHour2/1 shall be corrected)

但在调用context.savechanges()时,我得到了以下异常:

SqlException:违反主键约束 “工作时间”。无法在对象“dbo.workinghours”中插入重复键。 重复的键值为(0)。 语句已终止。**

我尝试了更多的context.savechanges()和attach()和其他命令,但总是失败,上面有例外。 context.configuration.proxyCreationEnabled默认设置为true。

这里是模型类:

public partial class Person
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public Person()
    {
        this.WorkingHours = new HashSet<WorkingHour>();
    }

    public string FirstName { get; set; }
    public string LastName { get; set; }
    public Nullable<System.DateTime> BirthDate { get; set; }
    public int Id { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<WorkingHour> WorkingHours { get; set; }
}


public partial class WorkingHour
{
    public int Id { get; set; }
    public int PersonId { get; set; }
    public System.DateTime Date { get; set; }
    public System.TimeSpan Start { get; set; }
    public float Hours { get; set; }

    public virtual Person Person { get; set; }
}