EntityFramework 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 = "aaa@qq.com",
UserPhone = "13100001111",
Password="aaaaaa"
};

UserModels m2 = new UserModels()
{
UserGUID = Guid.NewGuid().ToString(),
UserName = "张二",
UserNumber = "0002",
UserBirthDay = "1989.12.12",
UserMail = "bbb@qq.com",
UserPhone = "13100002222",
Password = "aaaaaa"
};

UserModels m3 = new UserModels()
{
UserGUID = Guid.NewGuid().ToString(),
UserName = "张三",
UserNumber = "0003",
UserBirthDay = "1989.12.12",
UserMail = "ccc@qq.com",
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 = "aaa@qq.com",
UserPhone = "13100001111",
Password="aaaaaa"
};

UserModels m2 = new UserModels()
{
UserGUID = Guid.NewGuid().ToString(),
UserName = "张二",
UserNumber = "0002",
UserBirthDay = "1989.12.12",
UserMail = "bbb@qq.com",
UserPhone = "13100002222",
Password = "aaaaaa"
};

UserModels m3 = new UserModels()
{
UserGUID = Guid.NewGuid().ToString(),
UserName = "张三",
UserNumber = "0003",
UserBirthDay = "1989.12.12",
UserMail = "ccc@qq.com",
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>