实体无法从相关 class 加载数据

Question

我有 3 个 class 这样的，我在 .net 上使用代码优先实体

public class PersonModel
{
    [Key]
    public int PersonID { get; set;  }
    public string FullName { get ; set ; }
    public string Phone { get ; set ; }
    public string Adress { get; set ; }
    public int NationalNumber { get ; set ; }
    public List<SpecialtyToPersonModel> SpecialtyToPerson { get ; set ; }
}
public class SpecialtyModel
{
    [Key]
    public int SpecialtyID { get; set; }
    public string SpecialtyName { get; set; }
    public List<SpecialtyToPersonModel> SpecialtyToPerson { get; set; }
}

public class SpecialtyToPersonModel{
    [Key]
    public int SpecialtyToPersonID { get ; set ; }
    public SpecialtyModel Specialty { get; set; }
    public PersonModel Person { get;set; }
}

当我需要像这样使用 specialityToPersonModel 时

var db = new EntityContext();
            var aaa = db.SpecialtyToPersons;
            return aaa.ToList(); // so Simple !

或者像这样：

var db = new EntityContext();
            var aaa = db.SpecialtyToPersons
            .Include(x=>x.Specialty)
            .Include(x=>x.Person);
            return aaa.ToList();

，它让我出局了这个错误：

Error Picture

An exception of type 'Npgsql.PostgresException' occurred in Microsoft.EntityFrameworkCore.dll but was not handled in user code: 'External component has thrown an exception.'

Answer 1

起初让数据库变坏是我的错，它来自数据库而不是代码...... 我更正了我的代码运行

dotnet ef migrations add InitialCreate

和

dotnet ef database update

再等等...无论如何...

Answer 2

所以 SpecialtyToPersonModel 不应该看起来更像这样

Public Class SpecialtyToPersonModel{
[Key]
Public int SpecialtyID { Get; Set; }
Public SpecialtyModel Specialty { Get; Set; }

Public int PersonID { Get; Set;  }
Public PersonModel Person { Get;Set; }

}

实体无法从相关 class 加载数据

Entity cannot load data from related class

entity-framework

linq

.net-core

ef-code-first

code-first