我知道SQL,但我很新的ORM,并在2017年VS使用的EntityFramework 6.2.0我认为该框架应使我能写多少有点像我会用POCO对象沙箱发挥,而不必应付主/外键。而变化,只要我调用下面的代码context.SaveChanges()保存在数据库中;我该怎么办(还)没有与EF6及其文档明白了吗?
我创建了两个表的人,并视对方有外键WorkingHours和1:N的关系。
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]
我创建从数据库模型。
我试图创建两个人物条目,每一个条目WorkingHours,并立即将其保存到数据库中。下面是代码:
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();我得到这个异常:
SQLEXCEPTION:PRIMARY KEY约束 'PK_WorkingHours' 的相关规定。不能插入对象“dbo.WorkingHours”重复键。重复的密钥值是(0)。该语句已终止。**
我尝试不同的方式与更多的context.SaveChanges()和附加()等订单,但我上面的异常故障始终。 context.Configuration.ProxyCreationEnabled设置为true为默认值。
这里的模型类:
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; }
}
第一个问题是WorkingHour
的主键是不是这就是为什么它总是被设置为Identity Key
的0
(int
的默认值)为每WorkingHour
,因此它被复制。
所以使Id
WorkingHour
[Id] [int] IDENTITY(1,1) NOT NULL
列
第二个问题是下面几行:
person2.WorkingHours.Add(workingHour1); // adding with person
person1.WorkingHours.Add(workingHour2); // adding with person
context.WorkingHours.Add(workingHour1); // adding individually
context.WorkingHours.Add(workingHour2); // adding individually
在这里,您可在上下文两次加入WorkingHour
。一个与Person
实体和其他可单独。因此,删除第二组,只是使用第一套如下:
person2.WorkingHours.Add(workingHour1);
person1.WorkingHours.Add(workingHour2);
我觉得你的问题是因为在[Id]
[WorkingHours]
的:
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]
如下更改,然后再试一次。
CREATE TABLE [dbo].[WorkingHours](
[Id] [int] IDENTITY(1,1) 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]