Domain Model & Code First

领域模型(Domain Medel)是从现实世界业务逻辑抽象为业务实体，所以这种模式用Code First更适合。利用上章案例接受下Entity Framework的Code first的强大功能。

安装EF

通过Package Manager Console安装EF：install-package entityframework默认会安装最新版本

Model创建类

注意关键字virtual,为实体关联到的属性

   public class BankAccount
    {
        public Guid BankAccountId { get; set; }
        public decimal Balance { get; set; }
        public string CustomerRef { get; set; }
        public virtual ICollection<Transaction> Transactions { get; set; }
    }

        public class Transaction
    {
        public int ID { get; set; }
        /// <summary>
        /// 保存到表中为BankAccount的外键
        /// </summary>
        public Guid BankAccountId { get; set; }
        public decimal Deposit { get; set; }
        public decimal Withdraw { get; set; }
        public string Reference { get; set; }
        public DateTime Date { get; set; }
        public virtual BankAccount BankAccount { get; set; }
    }

连接数据库指定及Context创建

webconfig文件中添加

  <connectionStrings>
     <add name="BankAccountContext" connectionString="Data Source=(LocalDb)\mssqllocaldb;AttachDbFilename=|DataDirectory|\BankAccount.mdf;Initial Catalog=BankAccount;Integrated Security=SSPI;" providerName="System.Data.SqlClient" />
  </connectionStrings>

添加数据上下文

   public class BankAccountContext: DbContext
    {
        public DbSet<BankAccount> BankAccounts { get; set; }
    }

利用Package Manager console完成数据库初始化

1. enable-migrations 会添加类Configuration,添加测试数据在 Seed方法中添加
   

 var bankAccounts = new List<BankAccount>
    {
        new BankAccount { BankAccountId=new Guid("27B5318E-EEA5-404C-ABE4-185C3411917E"), Balance=73.00m,CustomerRef="Bob Account" },
        new BankAccount { BankAccountId=new Guid("C2F81C0C-2EFD-40EF-BBC6-B394CF80EDF0"), Balance=456.00m,CustomerRef="Scott Test" },
        new BankAccount { BankAccountId=new Guid("903BB2F8-019A-47D6-88E4-DFD2AC9BB323"), Balance=0.00m,CustomerRef="Marys Account" }
    };

1. 添加本次对数据库的修改add-migration InitialCreate,以后每次每次为Model中类添加属性（对应表添加字段）都需要执行add-migration 生成的文件名再同步到数据库
   

2. 同步到数据库update-database,可用看到App_Data文件夹下添加了一个BankAccount.mdf文件