EntityFramework使用总结(与MVC4.0实现CURD操作)

EntityFramework使用总结(与MVC4.0实现CURD操作)

2013-08-03 22:00
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本篇文介绍一下Entity Framework Code First的简单用法，通过一个学生信息的增删查改来学习Entity Framework的使用及与存储过程的交互。我也是学习Entity Framework新手，有说的不对地方欢迎指正。

本文使用的开发环境为VS2010(sp1)+MVC4.0+EF5.0。

一、我们新建一个空MVC空项目



添加EntityFramework.dll的引用。
二、修改配web.config置文件(web.config为根目录下的)

添加EntityFramework配置和数据库连接字符串。

<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</configSections>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
</entityFramework>
<connectionStrings>
<add name="strConn" connectionString="Data Source=ERIC\SQLEXPRESS;Initial Catalog=EfSample;Integrated Security=True" providerName="System.Data.SqlClient" />
</connectionStrings>

三、在Models文件夹下新建Students.cs和DbHelper.cs

1、Students为学生信息实体类，并关联数据库表和其他一些属性说明，代码如下

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations.Schema;
using System.ComponentModel.DataAnnotations;

namespace MVCEF.Models
{
[Table("tb_Students", Schema = "dbo")]//关联数据表 dbo.tb_Students
public class Students
{
[Key]
public string Num { get; set; }
[MaxLength(10),Required(ErrorMessage="姓名不能为空")]
[Column(TypeName = "nvarchar")]
public string Name { get; set; }
public int Age { get; set; }
[MaxLength(10)]
[Column(TypeName = "varchar")]
public string Sex { get; set; }
[MaxLength(50)]
public string Class { get; set; }
}
}

View Code

说明：用属性Key说明的字段如果是int类型，EF会默认该字段对应的数据库表字段是自增的，好像是这样的，说的不对的请纠正。

2、DbHelper.cs主要创建数据库上下文，代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using System.Data.Entity.Migrations;

namespace MVCEF.Models
{
public class DbHelper:DbContext
{
public DbHelper()
: base("strConn")
{
//自动创建表，如果Entity有改到就更新到表结构
Database.SetInitializer<DbHelper>(new MigrateDatabaseToLatestVersion<DbHelper, ReportingDbMigrationsConfiguration>());
}
public DbSet<Students> Students { get; set; }
}
internal sealed class ReportingDbMigrationsConfiguration : DbMigrationsConfiguration<DbHelper>
{
public ReportingDbMigrationsConfiguration()
{
AutomaticMigrationsEnabled = true;//任何Model Class的修改將會直接更新DB
AutomaticMigrationDataLossAllowed = true;
}
}
}

[csharp]
view plaincopyprint?

<strong>说明：这里还需要请用<span style="color:#000000">System.Data.Entity.</span>DLL</strong>



[csharp]
view plaincopyprint?

<strong>要不然会报如下的一个错误：</strong>



四、我们创建表tb_Students和存储过程proc_1

CREATE TABLE [dbo].[tb_Students](
[Num] [varchar](128) NOT NULL,
[Name] [nvarchar](10) NOT NULL,
[Age] [int] NULL,
[Sex] [varchar](10) NULL,
[Class] [nvarchar](50) NULL,
PRIMARY KEY CLUSTERED
(
[Num] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

tb_Students

create proc proc_1
@Num varchar(128),
@Name varchar(50)
as
select * from dbo.tb_Students where Num=@Num and Name=@Name

proc_1
五、HomeController.cs调用EF方法实现增删改查。

方法都比较简单，这里就不做详细说明了

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using MVCEF.Models;
using System.Data;
using System.Data.SqlClient;

namespace MVCEF.Controllers
{
public class HomeController : Controller
{
DbHelper db = new DbHelper();
private static List<Students> listStu = new List<Students>()
{
new Students(){Num="s0001",Name="张三",Age=19,Sex="man",Class="计算机1班"},
new Students(){Num="s0002",Name="李四",Age=20,Sex="man",Class="计算机1班"},
new Students(){Num="s0003",Name="王五",Age=18,Sex="man",Class="计算机1班"},
new Students(){Num="s0004",Name="小红",Age=17,Sex="women",Class="计算机'\"1班"},
};
//
// GET: /Home/

public ActionResult Index()
{
//如果没有数据初始化数据
if (db.Students.Count() == 0)
{
listStu.ForEach(it =>
{
db.Students.Add(it);
});
db.SaveChanges();
}
List<Students> lst = db.Students.ToList();
//实现2：sql语句实现
//List<Students> lst = db.Students.SqlQuery("select * from tb_Students").ToList();
//与存储过程交互
// var result = db.Database.SqlQuery<Students>("exec proc_1 @p0,@p1", "s0001","张三1").ToList();
return View(lst);
}
public ActionResult Add()
{
return View(new Students());
}
[HttpPost]
public ActionResult Add(Students stu)
{
string Message = string.Empty;
if (db.Students.Where(it => it.Num == stu.Num).FirstOrDefault()!=null)
{
Message = "学号已经存在";
ViewBag.Msg = Message;
return View();
}
db.Students.Add(stu);
db.SaveChanges();
return RedirectToAction("Index","Home");
}

public ActionResult edit(string id)
{
var stu=db.Students.Where(it => it.Num == id).FirstOrDefault();
return View(stu);
}
[HttpPost]
public ActionResult edit(Students stu, FormCollection form,string id)
{
stu.Num = id;
db.Entry(stu).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index", "Home");
}
//删除
public ActionResult Del(string id)
{
/*方法1
var stu = db.Students.Where(it => it.Num == id).FirstOrDefault();
db.Entry(stu).State = EntityState.Deleted;
db.SaveChanges();
*/
//方法2
string strsql = "delete from tb_Students where Num=@Num";
SqlParameter[] paras =
{
new SqlParameter("@Num",SqlDbType.NVarChar,128)
};
paras[0].Value=id;
db.Database.ExecuteSqlCommand(strsql, paras);
db.SaveChanges();
return RedirectToAction("Index", "Home");
}
}
}

六、EF与存储过程交互

EF与存储过程交互详见Index方法： var result = db.Database.SqlQuery<Students>("exec proc_1 @p0,@p1", "s0001","张三1").ToList();
其中@p0,@p1为传入存储过程中的参数(依次对应存储过程参数@Num和@Name)。
我们在使用EF调用存储过程的时候传入的参数为@p0,@p1,@p2,@p3 依此排列下去(蛋疼不知道为啥这样设计)

但是如何获取存储过程的返回值和out参数我还没有找到，如果你知道希望能留下你的答案，共同学习。