mysql - 与 EF6、MySQL、MVC 错误的一对零/一关系

Question

我已经设置了实体:

public class User
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid UserId { get; set; }

    public string UserName { get; set; }
    public string Password { get; set; }

    public virtual Permissions Permissions { get; set; }
    ... 
}
public class Permissions
{
    [Key, ForeignKey("User")]
    public Guid UserId { get; set; }

    public virtual User User { get; set; }

    public bool UserType1 { get; set; }
    public bool UserType2 { get; set; }
    ...
}

目的是进行非常简单的设置，将权限分离到另一个表中。播种数据库时，我创建了一些具有正确设置的权限的用户(使用外部编辑器检查表，它们具有用户/权限条目的匹配键)。设置代码为:

public class EfDbInitializer : DropCreateDatabaseAlways<EfDbContext>
{
    protected override void Seed(EfDbContext context)
    {

        // Add admin user

        User admin = new User
        {
            UserName = "Admin",
            Password = "pass",
            FirstName = "Administrator",
            LastName = "Web",
            Permissions = new Permissions().SetAdminPermissions()
        };
        context.Users.Add(admin);

        context.Users.Add(new User { UserName = "User1", Password = "pass", FirstName = "John", LastName = "Doe", CreatedBy = admin, Permissions = new Permissions().AddFullPermissions().AddInstructorPermissions() });
        context.Users.Add(new User { UserName = "User2", Password = "pass", FirstName = "Jenny", LastName = "Doh", CreatedBy = admin, Permissions = new Permissions().AddFullPermissions().AddBasicPermissions() });
        context.Users.Add(new User { UserName = "User3", Password = "pass", FirstName = "Sasha", LastName = "Grey", CreatedBy = admin, Permissions = new Permissions().AddBasicPermissions() });
        context.Users.Add(new User { UserName = "User4", Password = "pass", FirstName = "Arnold", LastName = "Schwarzenegger", CreatedBy = admin, Permissions = new Permissions().AddInstructorPermissions() });          
        base.Seed(context);
    }
}

但是，当尝试访问相应的实体时，我总是遇到异常。例如，直接在 Controller 中我有

  if (filter == "Type1")
                    return View(_repository.Users.Where(p => p.Permissions.UserType1));

运行相应的操作会出现异常

System.Data.Entity.Core.EntityCommandExecutionException was unhandled by user code

我尝试在数据库配置中禁用延迟评估(Configuration.LazyLoadingEnabled = false;)。然后异常更改为:

An exception of type 'System.NullReferenceException' occurred in Web.WebUI.dll but was not handled in user code

检查 lambda 中的“p”对象，我发现字段已成功设置(用户名、密码等)，但权限字段为空。

我使用MySql.Data 6.9.6； MySql.Data.Entity 6.9.6； Entity Framework 6.1.3

Answer 1

尝试 _repository.Users.Include(u => u.Permissions).Where(p => p.Permissions.UserType1)

https://msdn.microsoft.com/en-us/data/jj574232.aspx