Question

public class abstract Animal
{
    [Key]
    public string AnimalId { get; set; }
    public Zoo Zoo { get; set; }
    public string ZooId { get; set; }    
}

public class Giraffe : Animal { }
public class Elephant : Animal { }

public class Zoo 
{
    [Key]
    public string ZooId { get; set; }
    public ICollection<Giraffe> Giraffes { get; set; }
    public ICollection<Elephant> Elephants { get; set; }
}

//OnModelCreating
builder.Entity<Animal>.HasOne(a => a.Zoo).WithMany().HasForeignKey(a => a.ZooId); //1
builder.Entity<Giraffe>.HasOne(g => g.Zoo).WithMany(z => Giraffes).HasForeignKey(g => g.ZooId); //2
builder.Entity<Elephant>.HasOne(g => g.Zoo).WithMany(z => Elephants ).HasForeignKey(g => g.ZooId); //3

//DbSets
public DbSet<Animal> Animals { get; set; }
public DbSet<Giraffe> Giraffes { get; set; } 
public DbSet<Elephant> Elephants { get; set; } 
public DbSet<Zoo> Zoos { get; set; }

我在这里收到错误：

导航属性＆＃39; Giraffes＆＃39;无法添加到实体类型＆＃39;动物园＆＃39;因为它的CLR类型ICollection Giraffe＆gt;不符合预期的CLR类型＆＃39; Animal＆＃39;。

可以通过替换 1

来修复

builder.Entity<Animal>.Ignore(a => a.Zoo); 
//both 2 and 3 here

然而它有一个非常严重的副作用：

await DbContextInstance.Animals.Include(a => a.Zoo).ToListAsync(); //Include throws ArgumentNullException

我可以解决此问题，而无需将ICollection<Giraffe> Giraffes和ICollection<Elephant> Elephants联合到ICollection<Animal> Animals吗？

与继承属性的关系

0 个答案: