c# - Ef Core 3 实体类型 XOrder 不能映射到表，因为它派生自 Order Only 基本实体类型可以映射到表

Question

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

public class Order 
{
    public Order()
    {
    }
    public virtual string Type { get; protected set; }
    public string Title { get; set; }
    public string Email { get; set; }
    public string Description { get; set; }
    public byte[] RowVersion { get; set; }

    public ICollection<OrderDetail> Details { get; set; }
}

public class OnlineOrder : Order
{
    public const string TypeName = "Online";
    public OnlineOrder() : base()
    {
    }
    public override string Type { get; protected set; } = TypeName;
    public OnlineType OnlineType { get; set; }
    public long FactorId { get; set; }
    public bool IsConfirmed { get; set; } = false;
}

public class OfflineOrder : Order
{
    public const string TypeName = "Offline";
    public OfflineOrder() : base()
    {
    }
    public override string Type { get; protected set; } = TypeName;
    public InputType InputType { get; set; }
    public long StoreId { get; set; }
}

并在所有实体的配置中使用此代码:

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

但是当运行迁移时得到这个异常:

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.

Answer 1

基于 this issue和 this breaking change在 ef 核心 3 ToTable()抛出异常，因为( 基于中断更改链接 ):

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.

所以我们改变配置类:

public virtual void Configure(EntityTypeBuilder<TEntity> builder)
{
    if (typeof(TEntity).BaseType == null)
        builder.ToTable(typeof(TEntity).Name, Schema);
}