實體框架通用實體繼承ID錯誤

Question

第2部分的問題，這從這裏繼續： EntityFramework Core - Update record fails with DbUpdateConcurrencyException

錯誤：

The derived type 'BinaryFile' cannot have KeyAttribute on property 'Id' since primary key can only be declared on the root type.

我試圖讓繼承了我的實體儘可能多的，所以我儘可能地去除重複。

我的繼承結構：

public interface IEntityMinimum 
{ 
    bool IsDeleted { get; set; } 
    byte[] Version { get; set; } 
    string CreatedBy { get; set; } 
} 

public class EntityMinimum : IEntityMinimum 
{ 
    public bool IsDeleted { get; set; } 
    [Timestamp] 
    public byte[] Version { get; set; } 
    public string CreatedBy { get; set; } 
} 

public interface IEntity : IEntityMinimum 
{ 
    object Id { get; set; } 
    DateTime CreatedDate { get; set; } 
    DateTime? ModifiedDate { get; set; } 
    string ModifiedBy { get; set; } 
} 

public interface IEntity<T> : IEntity 
{ 
    new T Id { get; set; } 
} 

public abstract class Entity<T> : EntityMinimum, IEntity<T> 
{ 
    [Key] 
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
    public T Id { get; set; } 

    object IEntity.Id 
    { 
     get => Id; 
     set => throw new NotImplementedException(); 
    } 

    private DateTime? _createdDate; 
    [DataType(DataType.DateTime)] 
    public DateTime CreatedDate 
    { 
     get => _createdDate ?? DateTime.UtcNow; 
     set => _createdDate = value; 
    } 

    [DataType(DataType.DateTime)] 
    public DateTime? ModifiedDate { get; set; } 

    public string ModifiedBy { get; set; } 
} 

public class EntityMaximum : Entity<int> 
{ 
    public bool IsActive { get; set; } 
} 

public class BinaryFile : EntityMaximum 
{ 
    public string Name { get; set; } 
    public string UniqueName { get; set; } 
    public Guid UniqueId { get; set; } 
    public byte[] Content { get; set; } 

    public virtual ICollection<Campaign> Campaigns { get; set; } 
} 

，當我用流利的API對Version場禁用isConcurrencyToken爲EntityMinimum類這樣我得到這個錯誤：

// https://stackoverflow.com/questions/44009020/entity-framework-isrowversion-without-concurrency-check 
    builder.Entity<EntityMinimum>().Property(x => x.Version).IsRowVersion().IsConcurrencyToken(false); 

這是必需的，因爲我如果我不在Version字段上禁用isConcurrencyToken，還有另一個問題：

Microsoft.EntityFrameworkCore.DbUpdateConcurrencyException: Database operation expected to affect 1 row(s) but actually affected 0 row(s). Data may have been modified or deleted since entities were loaded.

如果我刪除流利的API配置，它的工作原理，但不會更新，因爲Version字段具有[TimeStamp]屬性。

我在EntityMinimum這個[TimeStamp]Version領域追加Version每一個表，所以我可以使用TimeStamp爲手機和網絡之間的數據同步的目的。

我是否正確地做了這個結構，或者我應該擺脫[TimeStamp] byte[] Version，只是使用字符串Version並保存DateTime滴答作出同步的目的？

Answer 1

的問題是，通話

builder.Entity<EntityMinimum>() 

標誌着EntityMinimum類作爲實體（在EF核心產業戰略的一部分），而據我所知，您使用基類層次結構只是實現目的。

相反，你可以使用EF核心模型元數據服務關閉IsConcurrencyToken從EntityMinimum得出這樣的任何真正的實體的財產Version：

foreach (var entityType in modelBuilder.Model.GetEntityTypes()) 
{ 
    if (typeof(EntityMinimum).IsAssignableFrom(entityType.ClrType)) 
     entityType.FindProperty("Version").IsConcurrencyToken = false; 
}