实体框架如何映射复合实体

Question

我是EF的新手，我有这样的问题：我有四个实体，它们描述了地址的元素：

public partial class Region : BaseEntity
{
private ICollection<RegionCity> _regionCities;
public string Code { get; set; }
public string Name { get; set; }
public int Timezone { get; set; }
public virtual ICollection<RegionCity> RegionCities
{
get
{
return _regionCities ?? (_regionCities = new List<RegionCity>());
}
protected set { _regionCities = value; }
}
}
public partial class RegionCity : BaseEntity
{
private ICollection<CityStreet> _cityStreets;
public int RegionId { get; set; }
public string CityName { get; set; }
public virtual Region Region { get; set; }
public virtual ICollection<CityStreet> CityStreets
{
get { return _cityStreets ?? (_cityStreets = new List<CityStreet>()); }
protected set { _cityStreets = value; }
}
}
public partial class CityStreet : BaseEntity
{
public int CityId { get; set; }
public string StreetName { get; set; }
public virtual RegionCity City { get; set; }
}
public partial class FullAddress : BaseEntity
{
public int CityStreetId { get; set; }
public string HouseNum { get; set; }
public string OfficeNum { get; set; }
public virtual CityStreet Street { get; set; }
}

我有映射类：

public class RegionMap : EntityTypeConfiguration<Region>
{
public RegionMap()
{
this.ToTable("Region");
this.HasKey(r => r.Id);
this.Property(r => r.Name).HasMaxLength(64);
}
}
public class RegionCityMap : EntityTypeConfiguration<RegionCity>
{
public RegionCityMap()
{
this.ToTable("RegionCity");
this.HasKey(rc => rc.Id);
this.HasRequired(rc => rc.Region)
.WithMany(r => r.RegionCities)
.HasForeignKey(rc => rc.RegionId)
.WillCascadeOnDelete(false);
}
}
public class CityStreetMap : EntityTypeConfiguration<CityStreet>
{
public CityStreetMap()
{
this.ToTable("CityStreet");
this.HasKey(cs => cs.Id);
this.HasRequired(cs => cs.City)
.WithMany(c => c.CityStreets)
.HasForeignKey(cs => cs.CityId)
.WillCascadeOnDelete(false);
}
}
public class FullAddressMap : EntityTypeConfiguration<FullAddress>
{
public FullAddressMap()
{
this.ToTable("FullAddress");
this.HasKey(fu => fu.Id);
this.Property(fu => fu.HouseNum).HasMaxLength(16);
this.HasRequired(fu => fu.Street)
.WithMany()
.HasForeignKey(fu => fu.CityStreetId)
.WillCascadeOnDelete(false);
}
}

我如何写映射类，如果我将更改类FullAddress如下所示，这样它就可以证明它的名称：

public partial class FullAddress : BaseEntity
{
public int CityStreetId { get; set; }
public string HouseNum { get; set; }
public virtual Region Region { get; set; }
public virtual RegionCity City { get; set; }
public virtual CityStreet Street { get; set; }
}

我可以通过CityStreet绘制RegionCity地图，然后通过RegionCity绘制RegionCity吗？

Answer 1

您可以使用NotMapped属性遍历层次结构。或者，您可以声明额外的Navigaion属性和外键，以跳过级别。

如果您将键结构更改为使用复合键(无论如何，IMO是这里的最佳实践(，则可以执行其中任何一种操作。

例如

public class BaseEntity
{
}
public partial class Region : BaseEntity
{
public int RegionID { get; set; }
public string Code { get; set; }
public string Name { get; set; }
public int Timezone { get; set; }
public virtual ICollection<RegionCity> RegionCities { get; } = new HashSet<RegionCity>();
}

public partial class RegionCity : BaseEntity
{
[Key(), Column(Order=0)]
public int RegionId { get; set; }
[Key(), Column(Order = 1)]
public int RegionCityId { get; set; }
public string CityName { get; set; }
[ForeignKey("RegionId")]
public virtual Region Region { get; set; }
public virtual ICollection<CityStreet> CityStreets { get; } = new HashSet<CityStreet>();
}
public partial class CityStreet : BaseEntity
{
[Key(), Column(Order = 0)]
public int RegionId { get; set; }
[Key(), Column(Order = 1)]
public int RegionCityId { get; set; }
[Key(), Column(Order = 3)]
public int CityStreetId { get; set; }
public string StreetName { get; set; }
[ForeignKey("RegionId,RegionCityId")]
public virtual RegionCity RegionCity { get; set; }
public virtual ICollection<FullAddress> FullAddresses { get; } = new HashSet<FullAddress>();
}
public partial class FullAddress : BaseEntity
{
[Key(), Column(Order = 0)]
public int RegionId { get; set; }
[Key(), Column(Order = 1)]
public int RegionCityId { get; set; }
[Key(), Column(Order = 3)]
public int CityStreetId { get; set; }
[Key(), Column(Order = 4)]
public int FullAddressId { get; set; }
public string HouseNum { get; set; }
public string OfficeNum { get; set; }
[ForeignKey("RegionId,RegionCityId,CityStreetId")]
public virtual CityStreet Street { get; set; }
[NotMapped]
public virtual RegionCity RegionCity 
{
get
{
return this.Street.RegionCity;
}
set
{
this.Street.RegionCity = value;
}
}

[NotMapped]
public virtual Region Region
{
get
{
return this.Street.RegionCity.Region;
}
set
{
this.Street.RegionCity.Region = value;
}
}
}