如何在EF Core中將兩個類映射到一個表

Question

public class User
{
    public Account Account { get; set; }
    public string SomeInfo { get; set; }
    public Guid Id { get; set; }
}

public class Account
{
    public string Name { get; set; }
}

public class UserEntityTypeConfiguration : IEntityTypeConfiguration<User>
{
    public virtual void Configure(EntityTypeBuilder<User> builder)
    {
        builder.HasKey(x => x.Id);
        builder
            .Property(t => t.Id)
            .ValueGeneratedOnAdd();
    }
}

我可以映射到一個看起來像這樣的表嗎？

| Id | SomeInfo | AccountName |
-------------------------------
| 1  | info1    | name1       |
| 2  | info2    | NULL        |

映射后，1將映射到：

User.SomeInfo        is "info1"
User.Account         is not null
User.Account.Name    is "name1"

而加載2將導致

User.SomeInfo        is "info2"
User.Account         is null

有人可以幫忙嗎？

Answer 1

您想要的東西不能完全按照您想要的方式完成-使用與所有者位於同一表中的表拆分/擁有實體時，看起來EFCore要求相關實體不為null。

我認為有兩個選項-共享主鍵（需要兩個表，並且需要一個緊急/顯式負載才能用主體加載從屬實體）或按層次結構表（TPH）繼承（這需要兩種實體類型）。

共享主鍵：

public class SharedKeyPrincipal
{
    public int Id { get; set; }
    public int PrincipalProperty { get; set; }
    public SharedKeyDependent Dependent { get; set; }
}
public class SharedKeyDependent
{
    public int Id { get; set; }
    public int DependentProperty { get; set; }
    public SharedKeyPrincipal Principal { get; set; }
}

modelBuilder.Entity<SharedKeyDependent>()
    .HasOne( d => d.Principal )
    .WithOne( p => p.Dependent )
    .IsRequired()
    .HasForeignKey<SharedKeyDependent>( d => d.Id );

var principals = dbContext.Set<SharedKeyPrincipal>()
    .Include( p => p.Dependent )
    .ToArray();

TPH：

public class InheritanceBaseEntity
{
    public int Id { get; set; }
    public int BaseEntityProperty { get; set; }
}
public class InheritanceDerivedEntity : InheritanceBaseEntity
{
    public int DerivedEntityProperty { get; set; }
}

public DbSet<InheritanceBaseEntity> InheritanceBaseEntities { get; set; }
public DbSet<InheritanceDerivedEntity> InheritanceDerivedEntities { get; set; }

// use .OfType<InheritanceDerivedEntity>() to get entities that have a 
//     non-null 'value' for the related properties
var inheritanceEntities = dbContext.Set<InheritanceBaseEntity>().ToArray();