EF三层结构加接口实现增删改查

DbContext
  DbContext是EntityFramework很重要的部分，连接域模型与数据库的桥梁，是与数据库通信的主要类。

 

  

DbContext主要负责以下活动：

EntitySet:：DbContext包含了所有映射到表的entities

Querying：将Linq-To-Entities转译为Sql并发送到数据库

Change Tracking：从数据库获取entities后保留并跟踪实体数据变化

Persisting Data：根据entity状态执行Insert、update、delete命令

Caching：DbContext的默认第一级缓存，在上下文中的生命周期中存储entity

Manage Relationship：DbContext在DbFirst模式中使用CSDL、MSL、SSDL管理对象关系，Code first中使用fluent api 管理关系

增删改查操作
 IDAL

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace ADO.NETEFDemo
{
public interface IDAL<T> where T : class,new()
{
/// <summary>
/// 增
/// </summary>
/// <param name="model"></param>
/// <returns></returns>
int Add(T model);

/// <summary>
/// 删
/// </summary>
/// <param name="whereLambda"></param>
/// <returns></returns>
int Delete(Expression<Func<T, bool>> whereLambda);

/// <summary>
/// 改
/// </summary>
/// <param name="whereLambda"></param>
/// <param name="propertyNames"></param>
/// <param name="perpertyValues"></param>
/// <returns></returns>
int Update(Expression<Func<T, bool>> whereLambda, string[] propertyNames, object[] perpertyValues);

/// <summary>
/// 查
/// </summary>
/// <param name="whereLambda"></param>
/// <returns></returns>
List<T> GetModelList(Expression<Func<T, bool>> whereLambda);
}
}

  DAL

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace ADO.NETEFDemo
{
public class DAL<T> : IDAL<T> where T : class,new()
{
/// <summary>
/// 增
/// </summary>
/// <param name="model"></param>
/// <returns></returns>
public int Add(T model)
{
using (testbakEntities db = new testbakEntities())
{
db.Set<T>().Add(model);
return db.SaveChanges();
}
}

/// <summary>
/// 删
/// </summary>
/// <param name="whereLambda"></param>
/// <returns></returns>
public int Delete(Expression<Func<T, bool>> whereLambda)
{
using (testbakEntities db = new testbakEntities())
{
var dbQuery = db.Set<T>();

//先查询 对应表的 集合
var list = dbQuery.Where(whereLambda).ToList();

//遍历集合 里要删除的元素
foreach (var item in list)
{
//标记为 删除状态
dbQuery.Remove(item);
}
return db.SaveChanges();
}
}

/// <summary>
/// 改
/// </summary>
/// <param name="whereLambda"></param>
/// <param name="propertyNames"></param>
/// <param name="perpertyValues"></param>
/// <returns></returns>
public int Update(Expression<Func<T, bool>> whereLambda, string[] propertyNames, object[] perpertyValues)
{
using (testbakEntities db = new testbakEntities())
{
//1、查询要修改的对象集合
var list = db.Set<T>().Where<T>(whereLambda).ToList();

//2、获取要修改的对象的类型
Type t = typeof(T);

//3、循环要修改的实体对象，并根据要修改的属性名修改对象对应的属性值
foreach (var item in list)
{
//循环 要修改的属性 名称， 并 反射取出 t 中的 属性对象
for (int index = 0; index < propertyNames.Length; index++)
{
//获取要修改的属性名
string pName = propertyNames[index];

//获取属性对象
PropertyInfo pi = t.GetProperty(pName);

//调用属性对象的 SetValue方法 为当前循环的 item对象 对应的属性赋值
pi.SetValue(item, perpertyValues[index], null);
}
}
return db.SaveChanges();
}
}

/// <summary>
/// 查
/// </summary>
/// <param name="whereLambda"></param>
/// <returns></returns>
public List<T> GetModelList(Expression<Func<T, bool>> whereLambda)
{
using (testbakEntities db = new testbakEntities())
{
return db.Set<T>().Where(whereLambda).ToList();
}
}
}
}

 BLL

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace ADO.NETEFDemo
{
public static class BLL<T> where T : class,new()
{
private static IDAL<T> dal = new DAL<T>();

/// <summary>
/// 新增
/// </summary>
/// <param name="model"></param>
public static int Add(T model)
{
return dal.Add(model);
}

/// <summary>
/// 删除
/// </summary>
/// <param name="whereLambda"></param>
public static int Delete(Expression<Func<T, bool>> whereLambda)
{
return dal.Delete(whereLambda);
}

/// <summary>
/// 修改
/// </summary>
/// <param name="whereLambda"></param>
/// <param name="propertyNames"></param>
/// <param name="perpertyValues"></param>
/// <returns></returns>
public static int Update(Expression<Func<T, bool>> whereLambda, string[] propertyNames, object[] perpertyValues)
{
return dal.Update(whereLambda, propertyNames, perpertyValues);
}

/// <summary>
/// 查询
/// </summary>
/// <param name="whereLambda"></param>
/// <returns></returns>
public static List<T> GetModelList(Expression<Func<T, bool>> whereLambda)
{
return dal.GetModelList(whereLambda);
}
}
}

 调用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ADO.NETEFDemo
{
class Program
{
static void Main(string[] args)
{
GetArticleList();

AddArticle();

GetArticleList();

UpdateArticle();

GetArticleList();

DeleteArticel();

GetArticleList();

Console.ReadKey();
}

/// <summary>
/// 更新
/// </summary>
private static void UpdateArticle()
{
int result = BLL<t_crobot_reship_articles>
.Update(e => e.title.Contains("EF"), new[] { "title", "update_time" },
new object[] { "我是使用EF修改过标题的文章", DateTime.Now });
if (result >= 0)
{
Console.WriteLine("更新成功");
}
else
{
Console.WriteLine("更新失败");
}
Console.WriteLine();
}

/// <summary>
/// 删除
/// </summary>
private static void DeleteArticel()
{
int result = BLL<t_crobot_reship_articles>.Delete(e => e.title.Contains("EF"));
if (result >= 0)
{
Console.WriteLine("删除成功");
}
else
{
Console.WriteLine("删除失败");
}
Console.WriteLine();
}

/// <summary>
/// 新增
/// </summary>
private static void AddArticle()
{
t_crobot_reship_articles model = new t_crobot_reship_articles();
model.create_time = DateTime.Now;
model.module_id = 1;
model.adword_id = 20;
model.pick_id = 1;
model.vote_id = "1";
model.title = "我是使用EF添加的文章";
model.content_id = 1;
model.release_url = "http://www.sss.com";
model.state = true;
int result = BLL<t_crobot_reship_articles>.Add(model);
if (result >= 0)
{
Console.WriteLine("新增成功");
}
else
{
Console.WriteLine("新增失败");
}
Console.WriteLine();
}

/// <summary>
/// 获取文章列表
/// </summary>
private static void GetArticleList()
{
List<t_crobot_reship_articles> articleList = BLL<t_crobot_reship_articles>
.GetModelList(e => e.state == true);

Console.WriteLine("文章总数：" + articleList.Count.ToString());
foreach (t_crobot_reship_articles model in articleList)
{
Console.WriteLine("标题：" + model.title);
}

Console.WriteLine();
}
}
}

  结果
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版权声明：本文为CSDN博主「有梦的小草」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/loveyourselfjiuhao/article/details/82886595