ASP.NET MVC EF直接更新数据(不需查询)

EF(EntityFrameWork) ORM(对象关系映射框架/数据持久化框架)，根据实体对象操作数据表中数据的一种面向对象的操作框架，底层也是调用ADO.NET

ASP.NET MVC 项目会自动导入MVC程序集，因为默认.NET环境(GAC)中没有这个程序集

 1: EF数据上下文 继承于 DbContext ; DBQuery<T> ，支持延迟加载：只有当使用到数据的时候，才去查询数据库; 主要成员：表映射的实体集合 Set<T>,Entry<T>()

　　context.Model -->Dbset<Model>

　　context.set<Model>() -->Dbset<Model>

　　//使用状态版的时候，执行修改/删除的时候必须指定主键。

 2: EF中会为每个 管理的 实体对象 创建一个代理包装类对象，其中会跟踪 实体对象 的状态和每个属性的状态;

 3: [EF对象管理容器]: 每个通过EF数据上下文操作的实体对象，都需要存在上下文的容器中，一旦通过上下文的某个方法操作了实体对象后，那么上下文就会给它加一个状态标识。

     但调用上下文的SaveChanges方法的时候，上下文就会遍历容器中的所有对象，并检查他们的状态标识，并依照标识的值进行相应的增删改查sql操作

一、通常使用EF更新的方式，先查询出要修改的数据，然后再修改新的值；实体对象被修改的属性 在 代理包装类对象里 的对应属性状态会被修改记录下修改状态，

      等到调用SaveChanges时，EF会遍历其管理的每个实体对象，并根据其 包装类对象 的状态，生成增删改查sql语句并执行；

      此例中修改操作，会生成 修改的sql语句（注意：此处只为修改过的属性生成sql语句），最后执行。

 1 create database MyFirstEF
 2 on primary
 3 (
 4     name='MyFirstEF.mdf',
 5     --修改为自己电脑上SQL DB路径
 6     filename='E:\ProgramMSSQLServerDB\MyFirstEF.mdf',
 7     size=5mb,
 8     maxsize=100mb,
 9     filegrowth=10%
10 )
11 log on
12 (
13     name='MyFirstEF_log.ldf',
14     --修改为自己电脑上SQL DB路径
15     filename='E:\ProgramMSSQLServerDB\MyFirstEF_log.ldf',
16     size=2mb,
17     maxsize=100mb,
18     filegrowth=5mb
19 )
20 go
21 
22 use MyFirstEF
23 go
24 
25 create table CustomerInfo
26 (
27     id int identity(1,1) primary key,
28     customerName nvarchar(100) not null,
29     customerDate datetime
30 )
31 go
32 
33 insert into CustomerInfo values('aaaaa',getdate())
34 go
35 
36 select * from CustomerInfo
37 go
38 
39 create table OrderInfo
40 (
41   id int identity(1,1) primary key,
42   orderName nvarchar(100),
43   customerId int
44 )
45 go
46 
47 
48 alter table OrderInfo
49 add constraint FK_OrderInfo_CustomerInfo
50 foreign key(customerId) references CustomerInfo(id)
51 on delete cascade
52 on update cascade
53 
54 go
55 
56 
57 select * from CustomerInfo
58 select * from OrderInfo
create SQL
//EF context 对象
MyFirstEFEntities context = new MyFirstEFEntities();

//update
//1：先查询要修改的原数据
CustomerInfo customer = context.CustomerInfoes.Find(1);
//2：设置修改后的值
customer.customerDate = DateTime.Now;
//3：更新到数据库
context.SaveChanges();

二、为避免先查询数据库，可以直接将 被修改的实体对象 添加到 EF中管理(此时为附加状态Attached)，并手动设置其为未修改状态(Unchanged)，

     同时设置被修改的实体对象的包装类对象 对应属性为修改状态。

//EF context 对象
DbContext contextState = new MyFirstEFEntities();

//update
CustomerInfo customerState = new CustomerInfo();
customerState.id = 1;
customerState.customerDate = DateTime.Now;
customerState.customerName = "bbb";

//1: 标记当前对象，必须把必填字段都填写，否则会报错：System.Data.Entity.Validation.DbEntityValidationException
//1: 若此时未更新 非必填字段，则数据库会把非必填字段更新为null
contextState.Entry<CustomerInfo>(customerState).State = System.Data.EntityState.Modified;
contextState.SaveChanges();
//EF context 对象
DbContext contextState = new MyFirstEFEntities();

//update 2
CustomerInfo customerState = new CustomerInfo();
customerState.id = 1;
customerState.customerName = "dfdfdfdf";

//2: 针对某个属性，进行状态跟踪设置
//** 2.1: 如果使用 Entry 附加 实体对象到数据容器中，则需要手动 设置 实体包装类的对象 的 状态为 Unchanged**
//** 2.1: entry.State = System.Data.EntityState.Unchanged;
DbEntityEntry<CustomerInfo> entry = contextState.Entry<CustomerInfo>(customerState);
entry.State = System.Data.EntityState.Unchanged;
entry.Property("customerName").IsModified = true;
contextState.SaveChanges();
//EF context 对象
DbContext contextState = new MyFirstEFEntities();

//update 3
CustomerInfo customerState = new CustomerInfo();
customerState.id = 1;
customerState.customerName = "aaaaa";

//** 2.2: 如果使用 Attach 就不需要这句
//** 2.2: entry.State = System.Data.EntityState.Unchanged;
contextState.Set<CustomerInfo>().Attach(customerState);///直接针对属性进行状态设置，但是当前对象并没有被上下文跟踪
contextState.Entry<CustomerInfo>(customerState).Property("customerName").IsModified = true;
contextState.SaveChanges();
EF其他操作(多表增加操作/导航属性)：
#region 多表增加操作
DbContext dbContext = new MyFirstEFEntities();

CustomerInfo customerInfo = new CustomerInfo()
{
    customerName = "duobiaocaozuo",
    customerDate = DateTime.Now
};
dbContext.Set<CustomerInfo>().Add(customerInfo);

OrderInfo orderInfo1 = new OrderInfo()
{
    orderName = "bike1",
    customerId = customerInfo.id
};
dbContext.Set<OrderInfo>().Add(orderInfo1);

OrderInfo orderInfo2 = new OrderInfo()
{
    orderName = "bike2",
    customerId = customerInfo.id
};
dbContext.Set<OrderInfo>().Add(orderInfo2);

dbContext.SaveChanges();
#endregion
#region 导航属性
DbContext dbContext = new MyFirstEFEntities();

CustomerInfo customerInfo = new CustomerInfo()
{
    customerName = "daohangshuxing",
    customerDate = DateTime.Now
};

customerInfo.OrderInfoes.Add(new OrderInfo()
{
    orderName = "car1",
});

customerInfo.OrderInfoes.Add(new OrderInfo()
{
    orderName = "car2"
});

dbContext.Set<CustomerInfo>().Add(customerInfo);

dbContext.SaveChanges();

#endregion
  1 using System;
  2 using System.Collections.Generic;
  3 using System.Data.Entity;
  4 using System.Data.Entity.Infrastructure;
  5 using System.Linq;
  6 using System.Text;
  7 using System.Threading.Tasks;
  8 
  9 namespace _20160403_MyFirstEFDemo
 10 {
 11     class Program
 12     {
 13         static void Main(string[] args)
 14         {
 15 
 16             #region 方法
 17             ////EF context 对象
 18             //MyFirstEFEntities context = new MyFirstEFEntities();
 19             ////add
 20             //CustomerInfo customer = new CustomerInfo();
 21             //customer.customerName = "Test1";
 22             //customer.customerDate = DateTime.Now;
 23             //context.CustomerInfoes.Add(customer);
 24             //context.SaveChanges();
 25 
 26             ////update
 27             ////1：先查询要修改的原数据
 28             //CustomerInfo customer = context.CustomerInfoes.Find(1);
 29             ////2：设置修改后的值
 30             //customer.customerDate = DateTime.Now;
 31             ////3：更新到数据库
 32             //context.SaveChanges();
 33 
 34             ////Read
 35             //CustomerInfo customer = context.CustomerInfoes.Find(1);
 36             //if (customer != null)
 37             //{
 38             //    string strCustomerInfo = string.Format("name:{0},date:{1}", customer.customerName, customer.customerDate);
 39             //    Console.WriteLine(strCustomerInfo);
 40             //}
 41 
 42             ////delete
 43             //CustomerInfo customer = new CustomerInfo();
 44             //customer.id = 1;
 45             //context.CustomerInfoes.Attach(customer);
 46             //context.CustomerInfoes.Remove(customer);
 47             //context.SaveChanges();
 48             #endregion
 49 
 50             #region 状态
 51             //EF context 对象
 52             //DbContext contextState = new MyFirstEFEntities();
 53 
 54             ////add 1
 55             //CustomerInfo customerState = new CustomerInfo();
 56             //customerState.customerName = "testState1";
 57             //customerState.customerDate = DateTime.Now;
 58             //contextState.Set<CustomerInfo>().Add(customerState);
 59             //contextState.SaveChanges();
 60 
 61             ////add 2
 62             //CustomerInfo customerState = new CustomerInfo() { 
 63             //     customerName="stateTest111",
 64             //     customerDate=DateTime.Now
 65             //};
 66             //contextState.Entry<CustomerInfo>(customerState).State = System.Data.EntityState.Added;
 67             //contextState.SaveChanges();
 68 
 69             ////update 1
 70             //CustomerInfo customerState = new CustomerInfo();
 71             //customerState.id = 1;
 72             //customerState.customerDate = DateTime.Now;
 73             //customerState.customerName = "bbb";
 74 
 75             ////1: 标记当前对象，必须把必填字段都填写，否则会报错：System.Data.Entity.Validation.DbEntityValidationException
 76             ////1: 若此时未更新 非必填字段，则数据库会把非必填字段更新为null
 77             //contextState.Entry<CustomerInfo>(customerState).State = System.Data.EntityState.Modified;
 78             //contextState.SaveChanges();
 79 
 80             ////update 2
 81             //CustomerInfo customerState = new CustomerInfo();
 82             //customerState.id = 1;
 83             //customerState.customerName = "dfdfdfdf";
 84 
 85             ////2: 针对某个属性，进行状态跟踪设置
 86             ////** 2.1: 如果使用 Entry 附加 实体对象到数据容器中，则需要手动 设置 实体包装类的对象 的 状态为 Unchanged**
 87             ////** 2.1: entry.State = System.Data.EntityState.Unchanged;
 88             //DbEntityEntry<CustomerInfo> entry = contextState.Entry<CustomerInfo>(customerState);
 89             //entry.State = System.Data.EntityState.Unchanged;
 90             //entry.Property("customerName").IsModified = true;
 91             //contextState.SaveChanges();
 92 
 93             ////update 3
 94             //CustomerInfo customerState = new CustomerInfo();
 95             //customerState.id = 1;
 96             //customerState.customerName = "aaaaa";
 97 
 98             ////** 2.2: 如果使用 Attach 就不需要这句
 99             ////** 2.2: entry.State = System.Data.EntityState.Unchanged;
100             //contextState.Set<CustomerInfo>().Attach(customerState);///直接针对属性进行状态设置，但是当前对象并没有被上下文跟踪
101             //contextState.Entry<CustomerInfo>(customerState).Property("customerName").IsModified = true;
102             //contextState.SaveChanges();
103 
104             ////delete
105             //CustomerInfo customerState = new CustomerInfo()
106             //{
107             //    id = 2
108             //};
109             //contextState.Entry<CustomerInfo>(customerState).State = System.Data.EntityState.Deleted;
110             //contextState.SaveChanges();
111 
112             #endregion
113 
114             #region 多表增加操作
115             //DbContext dbContext = new MyFirstEFEntities();
116 
117             //CustomerInfo customerInfo = new CustomerInfo()
118             //{
119             //    customerName = "duobiaocaozuo",
120             //    customerDate = DateTime.Now
121             //};
122             //dbContext.Set<CustomerInfo>().Add(customerInfo);
123 
124             //OrderInfo orderInfo1 = new OrderInfo()
125             //{
126             //    orderName = "bike1",
127             //    customerId = customerInfo.id
128             //};
129             //dbContext.Set<OrderInfo>().Add(orderInfo1);
130 
131             //OrderInfo orderInfo2 = new OrderInfo()
132             //{
133             //    orderName = "bike2",
134             //    customerId = customerInfo.id
135             //};
136             //dbContext.Set<OrderInfo>().Add(orderInfo2);
137 
138             //dbContext.SaveChanges();
139             #endregion
140 
141             #region 导航属性
142             //DbContext dbContext = new MyFirstEFEntities();
143 
144             //CustomerInfo customerInfo = new CustomerInfo()
145             //{
146             //    customerName = "daohangshuxing",
147             //    customerDate = DateTime.Now
148             //};
149 
150             //customerInfo.OrderInfoes.Add(new OrderInfo()
151             //{
152             //    orderName = "car1",
153             //});
154 
155             //customerInfo.OrderInfoes.Add(new OrderInfo()
156             //{
157             //    orderName = "car2"
158             //});
159 
160             //dbContext.Set<CustomerInfo>().Add(customerInfo);
161 
162             //dbContext.SaveChanges();
163 
164             #endregion
165 
166             Console.WriteLine("OK");
167             Console.ReadKey();
168         }
169     }
170 }
EF(方法/状态/多表操作/导航属性)整体测试代码

参考文章：

ASP.NET EF(LINQ/Lambda查询)：http://www.cnblogs.com/Dr-Hao/p/5356928.html

ASP.NET EF 使用LinqPad 快速学习Linq：http://www.cnblogs.com/Dr-Hao/p/5357112.html

Ps:ViewBag,ViewData,TempData区别？

ViewBag 和 ViewData 数据"共享"，作用域为 当前 Action。

TempData 作用域跨 Action。

posted @ 2016-04-05 21:35  DrHao  阅读(19708)  评论(1)  编辑  收藏  举报