Ef Core 3 The entity type XOrder cannot be mapped to a table because it is derived from Order Only base entity types can be mapped to a table

huangapple
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英文:

Ef Core 3 The entity type XOrder cannot be mapped to a table because it is derived from Order Only base entity types can be mapped to a table

问题

问题：我们有一个名为Order的实体，具有一些继承类型，如OnlineOrder，OfflineOrder，...

  1. public class Order 
  2. {
  3.     public Order()
  4.     {
  5.     }
  6.     public virtual string Type { get; protected set; }
  7.     public string Title { get; set; }
  8.     public string Email { get; set; }
  9.     public string Description { get; set; }
  10.     public byte[] RowVersion { get; set; }
  11.     
  12.     public ICollection<OrderDetail> Details { get; set; }
  13. }
  15. public class OnlineOrder : Order
  16. {
  17.     public const string TypeName = "Online";
  18.     public OnlineOrder() : base()
  19.     {
  20.     }
  21.     public override string Type { get; protected set; } = TypeName;
  22.     public OnlineType OnlineType { get; set; }
  23.     public long FactorId { get; set; }
  24.     public bool IsConfirmed { get; set; } = false;
  25. }
  27. public class OfflineOrder : Order
  28. {
  29.     public const string TypeName = "Offline";
  30.     public OfflineOrder() : base()
  31.     {
  32.     }
  33.     public override string Type { get; protected set; } = TypeName;
  34.     public InputType InputType { get; set; }
  35.     public long StoreId { get; set; }
  36. }

并在所有实体的配置中使用以下代码：

  1. public virtual void Configure(EntityTypeBuilder<TEntity> builder)
  2. {
  3.     builder.ToTable(typeof(TEntity).Name, Schema);
  4. }

但是运行迁移时出现以下异常：

  1. The entity type 'OffineOrder' cannot be mapped to a table because it is derived from 'Order'. Only base entity types can be mapped to a table.
英文:

> Problem: We have Order entity with some inherit types such as : OnlineOrder , OfflineOrder , ...

  1. public class Order 
  2. {
  3.     public Order()
  4.     {
  5.     }
  6.     public virtual string Type { get; protected set; }
  7.     public string Title { get; set; }
  8.     public string Email { get; set; }
  9.     public string Description { get; set; }
  10.     public byte[] RowVersion { get; set; }
  11.     
  12.     public ICollection&lt;OrderDetail&gt; Details { get; set; }
  13. }
  15. public class OnlineOrder : Order
  16. {
  17.     public const string TypeName = &quot;Online&quot;;
  18.     public OnlineOrder() : base()
  19.     {
  20.     }
  21.     public override string Type { get; protected set; } = TypeName;
  22.     public OnlineType OnlineType { get; set; }
  23.     public long FactorId { get; set; }
  24.     public bool IsConfirmed { get; set; } = false;
  25. }
  27. public class OfflineOrder : Order
  28. {
  29.     public const string TypeName = &quot;Offline&quot;;
  30.     public OfflineOrder() : base()
  31.     {
  32.     }
  33.     public override string Type { get; protected set; } = TypeName;
  34.     public InputType InputType { get; set; }
  35.     public long StoreId { get; set; }
  36. }

and use this code in configuration of all entities:

  1. public virtual void Configure(EntityTypeBuilder&lt;TEntity&gt; builder)
  2. {
  3. 	builder.ToTable(typeof(TEntity).Name, Schema);
  4. }

but when run migration get this exception:

  1. The entity type &#39;OffineOrder&#39; cannot be mapped to a table because it is derived from &#39;Order&#39;. Only base entity types can be mapped to a table.

答案1

得分: 5

根据这个问题和这个重大变更，在 EF Core 3 中，ToTable() 抛出异常，因为（基于重大变更链接）：

> 从 EF Core 3.0 开始，并为以后的版本添加 TPT 和 TPC 支持做准备，调用派生类型上的 ToTable() 现在会抛出异常，以避免未来的意外映射更改。

因此，我们更改配置类：

  1. public virtual void Configure(EntityTypeBuilder<TEntity> builder)
  2. {
  3.     if (typeof(TEntity).BaseType == null)
  4.         builder.ToTable(typeof(TEntity).Name, Schema);
  5. }
英文:

Based this issue and this breaking change in ef core 3 ToTable() throw an exception because(based breaking change link):

> Starting with EF Core 3.0 and in preparation for adding TPT and TPC
> support in a later release, ToTable() called on a derived type will
> now throw an exception to avoid an unexpected mapping change in the
> future.

So we change configuration class:

  1. public virtual void Configure(EntityTypeBuilder&lt;TEntity&gt; builder)
  2. {
  3. 	if (typeof(TEntity).BaseType == null)
  4. 		builder.ToTable(typeof(TEntity).Name, Schema);
  5. }

答案2

得分: 0

另一个原因是在子实体（继承自另一个实体）上使用 SetTableName。请参阅此问题。

英文:

Another cause is using SetTableName on a child entity (inherited from another entity). See this issue

答案3

得分: -2

我目前通过调用 modelBuilder.Entity().ToTable(null); 来解决了这个问题。

英文:

I got around this for now by calling modelBuilder.Entity<yourEntity>().ToTable(null);

huangapple
  • 本文由 发表于 2020年1月3日 19:35:24
  • 转载请务必保留本文链接：https://go.coder-hub.com/59577928.html
  • .net-core
  • asp.net-core
  • c#
  • ef-core-3.0
  • entity-framework
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