EntityFramework使用总结(与MVC4.0实现CURD操作)

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=ERICSQLEXPRESS;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; }
    }
}

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;
        }
    }
}

说明：这里还需要请用System.Data.Entity.DLL

要不然会报如下的一个错误：

 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

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

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。

如果你有什么更好的关于EF的学习资料欢迎共享共同学习

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