[英]Complex relationship mappings in entity framework
我正在建立一個預訂系統。 我有角色(“ admin”,“ client”,“ employee”,“ student”)的用戶。
每個保留必須與角色客戶的用戶相關聯,它可能被分配給角色員工的用戶,也可能被分配給角色學生的用戶。
因此,在預訂類中,我具有用戶類型的屬性,並用[ForeignKey(“ AnytypeId”)]屬性標記了它們,以提示EF關系。
我在http://blog.stevensanderson.com/2011/01/28/mvcscaffolding-one-to-many-relationships/上看到了這樣的代碼
public class Reservation
{
public int ReservationID
{
get;
set;
}
[Required(ErrorMessage="Please provide a valid date")]
public DateTime ReservationDate
{
get;
set;
}
public DateTime ReservationEnd { get; set; }
public DateTime EntryDate
{
get;
set;
}
public DateTime UpdatedOn
{
get;
set;
}
public decimal Ammount
{
get;
set;
}
public decimal? Discount { get; set; }
[DataType(DataType.MultilineText)]
public string ServiceDetails { get; set; }
[DataType(DataType.MultilineText)]
public string Remarks { get; set; }
public string VoucherNumber { get; set; }
public int ServiceID
{
get;
set;
}
public Service Service
{
get;
set;
}
public string EmployeeId { get; set; }
[ForeignKey("EmployeeId")]
public User Employee { get; set; }
public string ClientId { get; set; }
[ForeignKey("ClientId")]
public User Client { get; set; }
public string StudentId { get; set; }
[ForeignKey("StudentId")]
public User Student { get; set; }
}
public class User
{
//[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
//public Guid UserId { get; set; }
[Key]
[Required(ErrorMessage = "User Name is required")]
[Display(Name = "User Name")]
[MaxLength(100)]
public string UserName { get; set; }
[Required]
[MaxLength(64)]
public byte[] PasswordHash { get; set; }
[Required]
[MaxLength(128)]
public byte[] PasswordSalt { get; set; }
[Required(ErrorMessage = "Email is required")]
[DataType(DataType.EmailAddress)]
[MaxLength(200)]
public string Email { get; set; }
[MaxLength(200)]
public string Comment { get; set; }
[Display(Name = "Approved?")]
public bool IsApproved { get; set; }
[Display(Name = "Crate Date")]
public DateTime DateCreated { get; set; }
[Display(Name = "Last Login Date")]
public DateTime? DateLastLogin { get; set; }
[Display(Name = "Last Activity Date")]
public DateTime? DateLastActivity { get; set; }
[Display(Name = "Last Password Change Date")]
public DateTime DateLastPasswordChange { get; set; }
public string address { get; set; }
public string LastName { get; set; }
public string FirstName { get; set; }
public string Phone { get; set; }
public bool? IsActive { get; set; }
public int? ClientTypeID { get; set; }
public virtual ClientType ClientType { get; set; }
public virtual ICollection<Role> Roles { get; set; }
public DateTime? PackageValidity { get; set; }
public virtual ICollection<Reservation> Reservations { get; set; }
}
public class UserMap : EntityTypeConfiguration<User>
{
public UserMap()
{
this.HasMany(u => u.Roles)
.WithMany(r => r.Users)
.Map(m =>
{
m.ToTable("RoleMemberships");
m.MapLeftKey("Username");
m.MapRightKey("RoleName");
});
}
}
現在,當我運行我的mvc3 EF代碼時,首先使用以下ERD和edmx模型為我動態創建了應用數據庫。
現在我遇到的幾個問題是:1.當我列出角色客戶端的所有用戶時,即使他們是數據庫中可用的保留,他們的保留屬性也始終顯示為0。 2.如果我嘗試刪除在數據庫中有保留的角色客戶端用戶,則會出現以下錯誤。
DELETE語句與REFERENCE約束“ Reservation_Client”沖突。 在數據庫“ CRSDB”的表“ dbo.Reservations”的“ ClientId”列中發生了沖突。 該語句已終止。
我檢查了ERD和edmx模型中的區域,是否沒有應用級聯刪除。 在刪除角色客戶的用戶但不刪除角色員工或學生的用戶時,如何指示EF刪除所有保留。
這段代碼可以解決問題
public class Reservation
{
public int ReservationID
{
get;
set;
}
[Required(ErrorMessage="Please provide a valid date")]
public DateTime ReservationDate
{
get;
set;
}
public DateTime ReservationEnd { get; set; }
public DateTime EntryDate
{
get;
set;
}
public DateTime UpdatedOn
{
get;
set;
}
public decimal Ammount
{
get;
set;
}
public decimal? Discount { get; set; }
[DataType(DataType.MultilineText)]
public string ServiceDetails { get; set; }
[DataType(DataType.MultilineText)]
public string Remarks { get; set; }
public String PaymentMethod { get; set; }
public string VoucherNumber { get; set; }
public int ServiceID
{
get;
set;
}
public virtual Service Service
{
get;
set;
}
public string EmployeeID { get; set; }
[ForeignKey("EmployeeID")]
public virtual User Employee { get; set; }
public string ClientID { get; set; }
[ForeignKey("ClientID")]
public virtual User Client { get; set; }
public string StudentID { get; set; }
[ForeignKey("StudentID")]
public virtual User Student { get; set; }
}
public class ReservationMap : EntityTypeConfiguration<Reservation>
{
public ReservationMap()
{
this.HasOptional(r => r.Client).WithMany().WillCascadeOnDelete(true);
this.HasOptional(r => r.Employee).WithMany().WillCascadeOnDelete(false);
this.HasOptional(r=>r.Student).WithMany().WillCascadeOnDelete(false);
}
}
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