Entity Framework Code First

Posted 2020-07-09 欣欣点灯

Entity Framework Code First定义

首先需要分析业务，提取项目需要的概念模型，将其用代码表示。

基本类型，枚举类型，复杂类型，以及它们之间的关系，继承，聚合，组合等方式。

枚举类型在Entity Framework 6 中已支持，可直接定义使用

复杂类型可在 使用[ComplexType] 标注在类上，也可在 FluentAPI 定义

继承在映射到数据表，默认是TPH 所有的属性映射到基类表中。

也可使用如下代码将每一个类型映射到一张表上

modelBuilder.Entity<PORequestEntry>().ToTable("PORequestEntrys"); 

如需将每个子类极其继承属性映射到一张表中，可使用MapInheritedProperties  方法。

modelBuilder.Entity<PORequestEntry>().Map(m =>
{
  m.MapInheritedProperties();
  m.ToTable("PORequestEntry");
});

将同一类型映射到不同表

modelBuilder.Entity<PORequest>()
.Map(m=>
{
  m.Properties(t => new{ t.FBillNo, t.FDate });
  m.ToTable(PORequest);
})
.Map(m=>
{
  m.Properties(t=> new { t.PoAddress.StreetNumber, t.PoAddress.StreetName });
  m.ToTable(PORequestAddress);
 });

将不同类型映射到同一表

modelBuilder.Entity<PORequestEntry>().ToTable("OtherTable"); 

之后定义上下文，使用Migrations 将定义的结构映射到资料库中。

如需初始化一些数据，可新增一个继承DropCreateDatabaseAlways 类的方法在上下文构造函数中调用即可

public class DBInitializer : DropCreateDatabaseAlways<ApplicationDbContext>
    {
        protected override void Seed(ApplicationDbContext context)
        {
            MGFunc mgfun1 = new MGFunc();
            mgfun1.Id = "001";
            mgfun1.FName = "权限管理";
            mgfun1.FUrl = "/Manage/MGFunc/index";
            mgfun1.CreatedDate = DateTime.Now;

            base.Seed(context);
        }
    }

 

    public enum POTranType
    {
        Office = 1,
        WearHourse = 2
    }

    public class PORequest : AuditableEntity
    {
        [MaxLength(100)]
        public string FBillNo { set; get; }

        public DateTime FDate { set; get; }

        public POTranType FTranType { set; get; }

        [MaxLength(100)]
        public string FStatus { set; get; }

        [MaxLength(200)]
        public string FNote { set; get; }

        public Address PoAddress { set; get; }

        public List<PORequestEntry> PORequestEntrys { set; get; }
    }

    [ComplexType]
    public class Address
    {
        [MaxLength(50)]
        public string StreetNumber { get; set; }

        [MaxLength(200)]
        public string StreetName { get; set; }
    }
    public class PORequestEntry : AuditableEntity
    {
        [MaxLength(100)]
        public string FInterID { set; get; }

        [Required]
        [Range(0, 500)]
        public decimal FQty { set; get; }

        public decimal FPrice { set; get; }

        public decimal FSecQty { set; get; }

        [MaxLength(100)]
        public string FItemID { set; get; }

        [ForeignKey("FItemID")]
        public ItemCore FItem { set; get; }
 

View Code

 public class ApplicationDbContext : DbContext
    { 
        public DbSet<MGFunc> MGFunc { set; get; }

        public DbSet<ItemCore> ItemCore { set; get; }

        public DbSet<PORequest> PORequest { set; get; }

        public DbSet<PORequestEntry> PORequestEntry { set; get; }

        public ApplicationDbContext()
            : base("SeCommerce2")
        {
            //Database.SetInitializer<ApplicationDbContext>(new DBInitializer());           
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            //modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
            //modelBuilder.Conventions.Add<StoreGeneratedIdentityKeyConvention>();
            
            base.OnModelCreating(modelBuilder);


        }
    }

View Code