c# - EF6如何映射这种零或一对一关系

Question

这是代码优先。

此关系的正确 Fluent 或数据注释是什么？

获取 EF 映射错误:无法确定类型“Model.SchoolInfo”和“Model.School”之间关联的主体端。该关联的主体端必须使用关系流畅的 API 或数据注释进行显式配置。

如果我添加

modelBuilder.Entity<School>().HasOptional(s => s.SchoolInfo).WithRequired(ss => ss.School);

我得到这个错误:在模型生成期间检测到一个或多个验证错误:School_SchoolInfo_Target::多重性在关系“School_SchoolInfo”中的角色“School_SchoolInfo_Target”中无效。由于 Dependent Role 属性不是关键属性，因此 Dependent Role 的重数上限必须为“*”。

SQL 表

table School
(
    int SchoolId not null PK
)

table SchoolInfo
(
    int SchoolInfoId not null PK IDENTITY
    int SchoolId not null FK UNIQUE
)

模型

class School
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    int schoolId;

    virtual SchoolInfo SchoolInfo;
}

class SchoolInfo
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    int schoolInfoId;

    int schoolId;

    virtual School School
}

Answer 1

如果你想实现1:1映射，表格应该是这样的:

在这种情况下，您的实体类将如下所示:

public class School
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int SchoolId { get; set; }

    public virtual SchoolInfo SchoolInfo { get; set; }
}

public class SchoolInfo
{
    [ForeignKey("School")]
    public int SchoolInfoId { get; set; }

    public virtual School School { get; set; }
}

您当前的表结构建议使用1:M 映射，为了将实体类映射到它，您需要做一些细微的更改:

public class School
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int SchoolId;

    public virtual IList<SchoolInfo> SchoolInfoes { get; set; }
}

public class SchoolInfo
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int SchoolInfoId { get; set; }

    public int SchoolId { get; set; }

    public virtual School School { get; set; }
}