【EF Core】Data Annotations之ComplexType 复杂类型

EF Core CodeFirst代码优先中的复杂类型

复杂类型在EF 4.1中很容易实现。想象客户实体类有一些像城市，邮政编码和街道的属性，我们发现把这些属性
组织成一个叫地址的复杂类型会比较好。

//Initial Customer Entity 
// 
public class Customer : Entity 
{ 
   public int CustomerId { get; set; } 
   public string FirstName { get; set; } 
   public string LastName { get; set; } 
   public string City { get; set; } 
   public string Street { get; set; } 
   public string ZipCode { get; set; }    
} 
Figure 22.- Initial plain Customer entity 
 
//Initial Customer Entity 
// 
public class Customer : Entity 
{ 
   public int CustomerId { get; set; } 
   public string FirstName { get; set; } 
   public string LastName { get; set; } 
   public Address Address { get; set; }    
} 
 
public class Address 
{    
   public string City { get; set; } 
   public string Street { get; set; } 
   public string ZipCode { get; set; }    
} 

考虑到我们不需要做其他任何事，EF转换会处理好复杂类型和映射到数据库中。默认转换会是
[复杂类型名]_[属性名]。因此，SQL schema会是这样的。

CREATE TABLE [dbo].[Customers]( 
  [CustomerId] [int] IDENTITY(1,1) NOT NULL, 
  [FirstName] [nvarchar](128) NULL, 
  [LastName] [nvarchar](128) NULL, 
  [Address_City] [nvarchar](128) NULL, 
  [Address_ZipCode] [nvarchar](128) NULL, 
  [Address_Street] [nvarchar](128) NULL, 
PRIMARY KEY CLUSTERED  
( 
  [CustomerId] ASC 
Address complex type 
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, 
IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) 
ON [PRIMARY] 
) ON [PRIMARY] 
 
GO 

我们可以修改这样的映射。如果我们用“Fluent API‟的方法，我们会使用DbModelBuilder类的ComplexType
方法，就像下面的代码。

//Using ‘ComplexType()’ method Fluent API – (Code in Data Persistence Infr.Layer) 
// 
protected override void OnModelCreating(DbModelBuilder modelBulder) 
{ 
   modelBuilder.Entity<Customer>() 
                              .Ignore(c => c.FullName); 
 
} 
protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
   modelBuilder.ComplexType<Address>() 
                 .Property(p => p.City) 
                 .HasColumnName("City"); 
 
   modelBuilder.ComplexType<Address>() 
                 .Property(p => p.Street) 
                 .HasColumnName("Street"); 
 
  modelBuilder.ComplexType<Address>() 
                .Property(p => p.ZipCode) 
                .HasColumnName("ZipCode"); 
} 

  ComplexType<>提供和Entity<>一样的配置。

  我们也可以把自定义映射的关系放到新派生于ComplexTypeConfiguration<TComplexType>的类中。

class AddressComplexTypeConfiguration 
                            :ComplexTypeConfiguration<Address> 
{ 
   public AddressComplexTypeConfiguration() 
   { 
       this.Property(p => p.ZipCode) 
           .HasColumnName("ZipCode"); 
Using the ComplexType method (Fluent API) 
 NOTE:  
  ComplexType<> does offer the same configuration possibilities than Entity<>.  
   
 
 
       this.Property(p => p.Street) 
           .HasColumnName("Street"); 
 
       this.Property(p => p.City) 
            .HasColumnName("City"); 
    } 
} 

  然后我们需要将它添加到OnModelCreating()方法的配置列表。这是复杂项目的推荐做法，这样我们
可以更好的构造它们。

public class MainBCUnitOfWork : DbContext 
{ 
  public IDbSet<Customer> Customers { get; set; } 
 
  protected override void OnModelCreating(DbModelBuilder modelBuilder) 
  { 
     modelBuilder.Configurations.Add(new AddressComplexTypeConfiguration());                    
  } 
}