还是以这两个表为例子

 

country包含零个或多个city， 这个外键关系是我后来加上去，原来没有。 然后再用Power Tool逆向， 产生如下代码

1:  using System.ComponentModel.DataAnnotations.Schema;

2:  using System.Data.Entity.ModelConfiguration;

3:   

4:  namespace EFEntity.Models.Mapping

5:  {

6:      public class cityMap : EntityTypeConfiguration
     

7:      {

8:          public cityMap()

9:          {

10:              // Primary Key

11:              this.HasKey(t => t.ID);

12:   

13:              // Properties

14:              this.Property(t => t.Name)

15:                  .IsRequired()

16:                  .HasMaxLength(35);

17:   

18:              this.Property(t => t.CountryCode)

19:                  .IsRequired()

20:                  .HasMaxLength(3);

21:   

22:              this.Property(t => t.District)

23:                  .IsRequired()

24:                  .HasMaxLength(20);

25:   

26:              // Table & Column Mappings

27:              this.ToTable("city", "world");

28:              this.Property(t => t.ID).HasColumnName("ID");

29:              this.Property(t => t.Name).HasColumnName("Name");

30:              this.Property(t => t.CountryCode).HasColumnName("CountryCode");

31:              this.Property(t => t.District).HasColumnName("District");

32:              this.Property(t => t.Population).HasColumnName("Population");

33:   

34: // Relationships //这里加了一个关系

35: this.HasRequired(t => t.country) //这个指向city 模型的 public virtual country country { get; set; }

36: .WithMany(t => t.cities) //这个指向country模型的  public virtual ICollection<city> cities { get; set; }

37: .HasForeignKey(d => d.CountryCode); //这个指向city模型的public string CountryCode { get; set; }

38:   

39:          }

40:      }

41:  }

以上是city映射， 下面是country映射

using System.ComponentModel.DataAnnotations.Schema;

using System.Data.Entity.ModelConfiguration;

namespace EFEntity.Models.Mapping

{

public class countryMap : EntityTypeConfiguration
     

{

public countryMap()

{

// Primary Key

this.HasKey(t => t.Code);

// Properties

this.Property(t => t.Code)

.IsRequired()

.HasMaxLength(3);

this.Property(t => t.Name)

.IsRequired()

.HasMaxLength(52);

this.Property(t => t.Continent)

.IsRequired()

.HasMaxLength(65532);

this.Property(t => t.Region)

.IsRequired()

.HasMaxLength(26);

this.Property(t => t.LocalName)

.IsRequired()

.HasMaxLength(45);

this.Property(t => t.GovernmentForm)

.IsRequired()

.HasMaxLength(45);

this.Property(t => t.HeadOfState)

.HasMaxLength(60);

this.Property(t => t.Code2)

.IsRequired()

.HasMaxLength(2);

// Table & Column Mappings

this.ToTable("country", "world");

this.Property(t => t.Code).HasColumnName("Code");

this.Property(t => t.Name).HasColumnName("Name");

this.Property(t => t.Continent).HasColumnName("Continent");

this.Property(t => t.Region).HasColumnName("Region");

this.Property(t => t.SurfaceArea).HasColumnName("SurfaceArea");

this.Property(t => t.IndepYear).HasColumnName("IndepYear");

this.Property(t => t.Population).HasColumnName("Population");

this.Property(t => t.LifeExpectancy).HasColumnName("LifeExpectancy");

this.Property(t => t.GNP).HasColumnName("GNP");

this.Property(t => t.GNPOld).HasColumnName("GNPOld");

this.Property(t => t.LocalName).HasColumnName("LocalName");

this.Property(t => t.GovernmentForm).HasColumnName("GovernmentForm");

this.Property(t => t.HeadOfState).HasColumnName("HeadOfState");

this.Property(t => t.Capital).HasColumnName("Capital");

this.Property(t => t.Code2).HasColumnName("Code2");

}

}

}

测试代码--延迟加载：

using (var context = new worldContext())

{

var country = from d in context.countries

where d.Name == "United States"

select d;

var countryUS = country.Single();

if (countryUS == null) return;

foreach (var city in countryUS.cities)

{

Console.WriteLine(city.Name);

}

Console.Read();

 

测试代码--预先加载：

using (var context = new worldContext())

{

var allCountries = context.countries.Include(p => p.cities);

foreach (var country in allCountries)

{

Console.WriteLine(country.Name);

foreach (var city in country.cities)

{

Console.WriteLine("__" + city.Name);

}

}

Console.Read();

}