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<city>
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<country>
{
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();
}