[英]Entity Framework Code First and linked entities
我有AspNetUser实体:
public partial class AspNetUser
{
public string Id { get; set; }
[Required]
[StringLength(256)]
[Index(IsClustered = false, IsUnique = true)]
public string UserName { get; set; }
....
接口:
public interface IProfile
{
string FirstName { get; set; }
string LastName { get; set; }
string Nickname { get; set; }
}
public interface IMembershipEntity
{
string AspNetUserId { get; set; }
AspNetUser AspNetUser { get; set; }
}
还有2个实体,它们每个都以FK链接到AspNetUser(都实现IProfile和IMembershipEntity):
public partial class Driver : IMembershipEntity, IProfile
{
#region IProfile
public string FirstName { get; set; }
public string LastName { get; set; }
public string Nickname { get; set; }
#endregion
#region IMembershipEntity
public string AspNetUserId { get; set; }
[ForeignKey("AspNetUserId")]
public virtual AspNetUser AspNetUser { get; set; }
#endregion
... driver fields
public class User : BaseEntity, IMembershipEntity, IProfile
{
#region IMembershipEntity
public string AspNetUserId { get; set; }
public virtual AspNetUser AspNetUser { get; set; }
#endregion
#region IProfile
public string FirstName { get; set; }
public string LastName { get; set; }
public string Nickname { get; set; }
#endregion
.... user fields
}
现在我需要一个需要从AspNetUser获取FirstName / LastName的方法,如下所示:
var element = (from i in db.AspNetUsers
select new UserElementDomain()
{
UserId = i.Id,
CompanyName = i.Company.Name,
FirstName = (get FirstName here),
LastName = (get LastName here),
RoleName = i.AspNetRoles.FirstOrDefault().Name,
SMSnumber = i.SMSnumber,
UserName = i.UserName,
.....
}).FirstOrDefault();
怎么做? 我可以向AspNetUser添加2个属性,例如:
public virtual User User { get; set; }
public virtual Driver Driver { get; set; }
但是怎么说,它应该是一个或零个链接,而不创建UserId / DriverId
即使使用它,我也必须编写如下代码:
FirstName = (i.User!=null)? i.User.FirstName : ((i.Driver!=null)?i.Driver.FirstName : String.Empty)
我不喜欢这段代码,因为当我再添加一个实体时,我必须查看所有代码并再添加一个条件。 如何正确做? 可能使用接口/继承吗?
我以前看过重复的代码,但是很少看到重复的数据结构。
根据您当前的代码,如果User.FirstName =“ A”&Driver.FirstName =“ B”,则结果仅为“ A”。 如果您有一个名为“ Employee”的新实体,如果您不使用当前样式对它进行硬编码,谁知道哪个名称将是3个实体中的真实名字?
您当前的代码可以简化为:
i.User?.FirstName ?? i.Driver?.FirstName ?? i.Whatever?.FirstName ?? String.Empty
但这是您要管理的真实数据吗?
我给你另外两个选择:
向根实体添加属性,在您的情况下为AspNetUser:
public class AspNetUser { .... public string FirstName { get; set; } public string LastName { get; set; } public string Nickname { get; set; } .... }
管理1个实体中的通用个人资料
public class AspNetUser { .... public virtual AspNetUserProfile AspNetUserProfile { get; set; } } public class AspNetUserProfile { [Key] public string Id { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public string Nickname { get; set; } .... [ForeignKey("Id")] public virtual AspNetUser AspNetUser { get; set; } }
然后在您的代码中:
db.AspNetUsers.Select(i => new UserElementDomain()
{
UserId = i.Id,
CompanyName = i.Company.Name,
FirstName = i.AspNetUserProfile?.FirstName,
LastName = i.AspNetUserProfile?.LastName,
RoleName = i.AspNetRoles.FirstOrDefault().Name,
SMSnumber = i.SMSnumber,
UserName = i.UserName,
.....
})
如果驱动程序/用户/ Empolyee要获取名字,请使用:
Empolyee.AspNetUser.AspNetUserProfile?.FirstName
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