EntityFramework用法探索（三）CodeFirst流畅API-阿里云开发者社区

EntityFramework用法探索（三）CodeFirst流畅API

2017-12-06 1398

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简介：

Code First Fluent API，使用流畅API来定义模型映射。

同样使用与上文 Database First 模式相同的例子，假设需要设计一个零售系统，我们先构建一个 Customer 类。

1   public class Customer
2   {
3     public long Id { get; set; }
4     public string Name { get; set; }
5     public string Address { get; set; }
6     public string Phone { get; set; }
7   }

这次没有使用属性来指定对应表名称、主键等。

使用代码创建影射，

 1   public class CustomerMap : EntityTypeConfiguration<Customer>
 2   {
 3     public CustomerMap()
 4     {
 5       // Primary Key
 6       this.HasKey(t => t.Id);
 7 
 8       // Properties
 9       this.Property(t => t.Name)
10           .IsRequired()
11           .HasMaxLength(256);
12 
13       this.Property(t => t.Phone)
14           .IsRequired()
15           .HasMaxLength(256);
16 
17       // Table & Column Mappings
18       this.ToTable("Customer", "STORE");
19       this.Property(t => t.Id).HasColumnName("Id");
20       this.Property(t => t.Name).HasColumnName("Name");
21       this.Property(t => t.Address).HasColumnName("Address");
22       this.Property(t => t.Phone).HasColumnName("Phone");
23 
24       // Relationships
25       //this.HasRequired(t => t.Status)
26       //    .WithMany(t => t.CustomerStatus)
27       //    .HasForeignKey(d => d.Status);
28     }
29   }

在上下文对象中覆写OnModelCreating方法来添加影射配置，

 1   public class RetailEntities : DbContext
 2   {
 3     static RetailEntities()
 4     {
 5       //Database.SetInitializer<RetailEntities>(new CreateDatabaseIfNotExists<RetailEntities>());
 6       //Database.SetInitializer<RetailEntities>(new DropCreateDatabaseAlways<RetailEntities>());
 7       //Database.SetInitializer<RetailEntities>(new DropCreateDatabaseIfModelChanges<RetailEntities>());
 8       Database.SetInitializer<RetailEntities>(null);
 9     }
10 
11     public RetailEntities()
12       : base("Name=RetailEntities")
13     {
14     }
15 
16     public DbSet<Customer> Customers { get; set; }
17 
18     protected override void OnModelCreating(DbModelBuilder modelBuilder)
19     {
20       modelBuilder.Configurations.Add(new CustomerMap());
21     }
22   }

ICustomerRepository接口和实现依然类似，

 1     public void InsertCustomer(DomainModels.Customer customer)
 2     {
 3       using (RETAILContext context = new RETAILContext())
 4       {
 5         Customer entity = Mapper.Map<DomainModels.Customer, Customer>(customer);
 6         context.Customers.Add(entity);
 7         context.SaveChanges();
 8 
 9         customer.Id = entity.Id;
10       }
11     }
12 
13     public void UpdateCustomer(DomainModels.Customer customer)
14     {
15       using (RETAILContext context = new RETAILContext())
16       {
17         Customer entity = context.Customers.AsQueryable().Single(c => c.Id == customer.Id);
18 
19         entity.Name = customer.Name;
20         entity.Address = customer.Address;
21         entity.Phone = customer.Phone;
22 
23         context.SaveChanges();
24       }
25     }

同样的测试代码，

 1       ICustomerRepository customerRepository = new CustomerRepository();
 2 
 3       // =============== 增 ===============
 4       Console.ForegroundColor = ConsoleColor.DarkRed;
 5 
 6       DomainModels.Customer customer1 = new DomainModels.Customer()
 7       {
 8         Name = "Dennis Gao",
 9         Address = "Beijing",
10         Phone = "18888888888",
11       };
12       customerRepository.InsertCustomer(customer1);
13       Console.WriteLine(customer1);