5

我有以下域对象：

public class Person 
{
    public int Id {get; set;}
    public int? FatherId {get; set;}
    public int? MotherId {get; set;}
    public int? HomeChurchId {get; set;}
    public int? BirthCountryId {get; set;}

    public Parent Father {get; set;}
    public Parent Mother {get; set;}
    public Church HomeChurch {get; set;}
    public Country BirthCountry {get; set;}
}

public class Parent
{
    public int Id {get; set;}
    ...
}

public class Church
{
    public int Id {get; set;}
    ...
}

public class Country
{
    public int Id {get; set;}
    ...
}

映射 Person 时，所有这些属性的映射方式几乎相同：

HasOptional(p => p.Father).WithMany().HasForeignKey(p => p.FatherId);
HasOptional(p => p.BirthCountry).WithMany().HasForeignKey(p => p.BirthCountryId);    
...

问题是，使用 BirthCountry 时，我在尝试查询 Person 时收到以下错误：

One or more validation errors were detected during model generation:

System.Data.Entity.Edm.EdmAssociationType: : Multiplicity conflicts with the
referential constraint in Role 'Person_BirthCountry_Target' in relationship
'Person_BirthCountry'. Because all of the properties in the Dependent Role are 
non-nullable, multiplicity of the Principal Role must be '1'.

如果我删除 BirthCountry 属性（和映射）一切正常。令我困惑的是 BirthCountry 的设置就像 Person 中的所有其他可为空的属性一样。为什么其他属性没有给我同样的错误？

感谢您提供的任何帮助！

4

1 回答 1

11

无知不是幸福……它只是令人沮丧。

我终于意识到我在 BirthCountryId 上有一个 [Required] 属性。这导致了问题......这完全有道理。我不能同时告诉 EF 它是可选的和必需的。

希望这可以使其他人摆脱与我一样的挫败感。

于 2013-04-16T15:38:21.640 回答