EntityFramewrok Codefirst 数据库初始化

我们希望当程序运行时自动完成数据库的创建并预置初始值。自己的Context名为 DataBaseContet

有两种方法：

1、在Global.asax中添加  Database.SetInitializer<DataBaseContext>(new DatabaseInitializer());

2、配置文件中添加 contexts 节点， 节点中指定类名与命名空间

<entityFramework>
    <contexts>
      <context type="DataBase.DataBaseContext, DataBase" disableDatabaseInitialization="false">
        <databaseInitializer type="DataBase.DatabaseInitializer, DataBase" />
      </context>
    </contexts>
    <defaultConnectionFactory type="DataBase.DataBaseContext, DataBase">
      <parameters>
        <parameter value="v11.0" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>

其中 DataBaseContext为：

namespace DataBase
{
    public class DataBaseContext : DbContext
    {
        public DataBaseContext()
            : base("default")
        {

            //是否启用延迟加载:
            //  true:   延迟加载（Lazy Loading）：获取实体时不会加载其导航属性，一旦用到导航属性就会自动加载
            //  false:  直接加载（Eager loading）：通过 Include 之类的方法显示加载导航属性，获取实体时会即时加载通过 Include 指定的导航属性
            this.Configuration.LazyLoadingEnabled = true;
            this.Configuration.AutoDetectChangesEnabled = true;  //自动监测变化，默认值为 true
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
        }
        public DbSet<UserModels> UserContext { get; set; }
        public DbSet<PigModels> PigContext { get; set; }
    }
}

自定义的数据初始化方法：DatabaseInitializer，其中继承的是DropCreateDatabaseAlways 只为演示用, 实际项目中根据需要选择。

namespace DataBase
{
    public class DatabaseInitializer : DropCreateDatabaseAlways<DataBaseContext>
    {
        protected override void Seed(DataBaseContext context)
        {
            UserModels m1 = new UserModels()
            {
                UserGUID = Guid.NewGuid().ToString(),
                UserName = "张一",
                UserNumber = "0001",
                UserBirthDay = "1990.1.1",
                UserMail = "[email protected]",
                UserPhone = "13100001111",
                Password="aaaaaa"
            };

            UserModels m2 = new UserModels()
            {
                UserGUID = Guid.NewGuid().ToString(),
                UserName = "张二",
                UserNumber = "0002",
                UserBirthDay = "1989.12.12",
                UserMail = "[email protected]",
                UserPhone = "13100002222",
                Password = "aaaaaa"
            };

            UserModels m3 = new UserModels()
            {
                UserGUID = Guid.NewGuid().ToString(),
                UserName = "张三",
                UserNumber = "0003",
                UserBirthDay = "1989.12.12",
                UserMail = "[email protected]",
                UserPhone = "13100003333",
                Password = "aaaaaa"
            };

            try { // 写数据库 

            context.UserContext.Add(m1);
            context.UserContext.Add(m2);
            context.UserContext.Add(m3);
            context.SaveChanges();
            }
            catch (DbEntityValidationException dbEx) { }
            base.Seed(context);
        }

    }
}

具体步骤：

首先通过NuGet工具安装EntityFramework,本人用的为6.0版本。

1、建立实体类：

namespace DatabaseModels
{
    public class UserModels
    {
        [Required]
        [Key]
        public string UserGUID { get; set; }
        [Required]
        [Display(Name = "用户名")]
        public string  UserName { get; set; }
        [Display(Name = "用户工号")]
        public string UserNumber { get; set; }

        [Required]
        [DataType(DataType.Password)]
        [Display(Name = "密码")]
        public string Password { get; set; }
        [Display(Name = "出生日期")]
        public string UserBirthDay { get; set; }
        [Display(Name = "电话号")]
        public string UserPhone { get; set; }
        [Display(Name = "邮箱")]
        public string UserMail { get; set; }

    }
}

2、建立Context 继承 DbContext

namespace DataBase
{
    public class DataBaseContext : DbContext
    {
        public DataBaseContext()
            : base("default")
        {

            //是否启用延迟加载:
            //  true:   延迟加载（Lazy Loading）：获取实体时不会加载其导航属性，一旦用到导航属性就会自动加载
            //  false:  直接加载（Eager loading）：通过 Include 之类的方法显示加载导航属性，获取实体时会即时加载通过 Include 指定的导航属性
            this.Configuration.LazyLoadingEnabled = true;
            this.Configuration.AutoDetectChangesEnabled = true;  //自动监测变化，默认值为 true
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
        }
        public DbSet<UserModels> UserContext { get; set; }
            }
}

3、创建数据初始方法

namespace DataBase
{
    public class DatabaseInitializer : DropCreateDatabaseAlways<DataBaseContext>
    {
        protected override void Seed(DataBaseContext context)
        {
            UserModels m1 = new UserModels()
            {
                UserGUID = Guid.NewGuid().ToString(),
                UserName = "张一",
                UserNumber = "0001",
                UserBirthDay = "1990.1.1",
                UserMail = "[email protected]",
                UserPhone = "13100001111",
                Password="aaaaaa"
            };

            UserModels m2 = new UserModels()
            {
                UserGUID = Guid.NewGuid().ToString(),
                UserName = "张二",
                UserNumber = "0002",
                UserBirthDay = "1989.12.12",
                UserMail = "[email protected]",
                UserPhone = "13100002222",
                Password = "aaaaaa"
            };

            UserModels m3 = new UserModels()
            {
                UserGUID = Guid.NewGuid().ToString(),
                UserName = "张三",
                UserNumber = "0003",
                UserBirthDay = "1989.12.12",
                UserMail = "[email protected]",
                UserPhone = "13100003333",
                Password = "aaaaaa"
            };

            try { // 写数据库 

            context.UserContext.Add(m1);
            context.UserContext.Add(m2);
            context.UserContext.Add(m3);
            context.SaveChanges();
            }
            catch (DbEntityValidationException dbEx) { }
            base.Seed(context);
        }

    }
}

4、

方法一、在Global.asax中 添加 Database.SetInitializer<DataBaseContext>(new DatabaseInitializer());

或者：方法二：在配置文件中添加节点：

<contexts>
      <context type="DataBase.DataBaseContext, DataBase" disableDatabaseInitialization="false">
        <databaseInitializer type="DataBase.DatabaseInitializer, DataBase" />
      </context>
    </contexts>