再接再厉VS 2008 sp1 + .NET 3.5 sp1(1) - Entity Framework(实体框架)之添加、查询、更新和删除的Demo

<ul> 
        <li>ADO.NET Entity Framework(EF) - 就当是微软的ORM吧，可以将概念模型映射到逻辑模型，从而使用概念模型做开发 </li> 
        <li>Entity - 在EF中就是实体的概念 </li> 
        <li>Entity Data Model(EDM) - 实体数据模型，表现为一组映射到数据源的实体和关系</li> 
        <li>LINQ  to Entities - 和LINQ  to XXX一样，对EF中的实体做LINQ</li> 
        <li>Entity SQL(ESQL) - 一种类似sql的查询语言，针对概念模型做查询</li> 
        <li>csdl - Conceptual schema definition language 概念架构定义语言</li> 
        <li>ssdl - Store schema definition language 存储架构定义语言 </li> 
        <li>msl - Mapping specification language 映射规范语言</li> 
        <li>csdl, ssdl, msl均为基于XML的语言。.edmx文件同时包含这3种语言所描述的信息</li> 
</ul> 
<ul> 
        <li>Entity - 实体</li> 
        <li>Entity  Class - 实体类。至少要有一个实体键（Key Properties）</li> 
        <li>Entity  Set - 实体集。实体集中包含着若干实体</li> 
        <li>Association - 关联。实体类之间的关系。导航属性就是由关联来定义的</li> 
        <li>Association  Set - 关联集。关联集中包含着若干关联</li> 
        <li>Entity Container - 实体容器。实体容器中包含着若干实体集和关联集</li> 
</ul> 
<ul> 
        <li>概念模型中必须要有实体键，实体键与表中的主键相对应，所以表中必须要有主键</li> 
        <li>存储模型的字段如果有主键键或非空约束，则概念模型中必需要有相应的属性与之映射</li> 
        <li>概念模型中存在的属性，必须在存储模型中有与之映射的字段</li> 
        <li>作为映射条件的字段不能映射到属性上</li> 
        <li>要实现继承的话，就要使用映射条件来进行筛选</li> 
</ul> 
<ul> 
        <li>EntityConnection - 与存储模型的连接。相当于SqlConnection</li> 
        <li>EntityCommand - 对 EDM 执行的命令。相当于SqlCommand</li> 
        <li>EntityDataReader - 以只读、只进的数据流的方式获取数据（内存中始终只有一行）。相当于SqlDataReader</li> 
</ul>

<%@ Page Title= "添加、查询、更新和删除的Demo" Language= "C#" MasterPageFile= "~/Site.master" AutoEventWireup= "true" 
        CodeFile= "Demo.aspx.cs"  Inherits= "EntityFramework_Demo" %> 

<asp:Content ID= "Content1" ContentPlaceHolderID= "head" runat= "Server"> 
</asp:Content> 
<asp:Content ID= "Content2" ContentPlaceHolderID= "ContentPlaceHolder1" runat= "Server"> 
        <div style= "margin: 10px;"> 
                CategoryName：<asp:TextBox ID= "txtCategoryName" runat= "server" /> 
                Description：<asp:TextBox ID= "txtDescription" runat= "server" /> 
                <asp:Button ID= "btnAddCategory" runat= "server" Text= "添加产品类别" OnClick= "btnAddCategory_Click" /> 
        </div> 
        <div style= "margin: 10px;"> 
                <asp:GridView ID= "GridView1" DataKeyNames= "CategoryID" runat= "server" AutoGenerateColumns= "false" 
                        OnRowDeleting= "GridView1_RowDeleting" OnRowCancelingEdit= "GridView1_RowCancelingEdit" 
                        OnRowEditing= "GridView1_RowEditing" OnRowUpdating= "GridView1_RowUpdating" OnSelectedIndexChanged= "GridView1_SelectedIndexChanged"> 
                        <Columns> 
                                <asp:BoundField DataField= "CategoryID" HeaderText= "ID" ReadOnly= "true" /> 
                                <asp:BoundField DataField= "CategoryName" HeaderText= "CategoryName" /> 
                                <asp:BoundField DataField= "Description" HeaderText= "Description" /> 
                                <asp:CommandField ShowSelectButton= "True" ShowEditButton= "True" ShowDeleteButton= "True"> 
                                </asp:CommandField> 
                        </Columns> 
                </asp:GridView> 
        </div> 
        <div style= "margin: 10px;"> 
                <asp:GridView ID= "GridView2" runat= "server"> 
                </asp:GridView> 
        </div> 
</asp:Content>

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.Web.UI; 
using System.Web.UI.WebControls; 

// 在 System.Data.Entity.dll 程序集中 
using System.Data.Objects; 
using System.Data.Objects.DataClasses; 

using VS2008SP1.Business; 

public partial  class EntityFramework_Demo : System.Web.UI.Page 
{ 
void Page_Load() void Page_Load(object sender, EventArgs e) 
        { 
                 if (!Page.IsPostBack) 
                { 
                        BindData(); 
                } 
        } 

        void BindData() 
        { 
                using (var ctx =  new NorthwindEntities()) 
                { 
                        // 将 System.Data.Objects.ObjectQuery<Categories> 绑定到 Gridview1 
                        GridView1.DataSource = ctx.Categories; 
                        GridView1.DataBind(); 
                } 
        } 

void btnAddCategory_Click() void btnAddCategory_Click(object sender, EventArgs e) 
        { 
                // NorthwindEntities -    继承自 System.Data.Objects.ObjectContext 
                // ObjectContext -    以对象（这些对象是 EDM 中定义的实体类型的实例）的形式与数据进行交互 
                using (var ctx =  new NorthwindEntities()) 
                { 
                        // CreateObjectName - 实体类 的 CreateObjectName 静态方法用于创建实体类的新实例 
                        //         构造函数的参数为对应的实体类的必填字段 
                        //         如果参数属于自增列，如本例中的 categoryID ，可以先对其赋予任意值 
                        var category = Categories.CreateCategories(-1, txtCategoryName.Text); 
                        category.Description = txtDescription.Text; 

                         for (int i = 0; i < 10; i++) 
                        { 
                                category.Products.Add( new Products() { ProductName =  "测试用" + i.ToString()}); 
                        } 

                        // AddToEntitySetName() - 将需要添加的对象添加到对象上下文中 
                        ctx.AddToCategories(category); 

                        // SaveChanges() - 将所有更新保存到相关存储区中 
                        ctx.SaveChanges(); 

                        // SaveChanges() 之后就可以通过 category.CategoryID 来取得其自增列在数据库中所保存的值 
                        Page.ClientScript.RegisterStartupScript(this.GetType(),  "js",  "alert('CategoryID: " + category.CategoryID + "');", true); 
                } 

                GridView1.EditIndex = -1; 
                BindData(); 
        } 

void GridView1_RowDeleting() void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e) 
        { 
                using (var ctx =  new NorthwindEntities()) 
                { 
                        var categoryId = (int)GridView1.DataKeys[e.RowIndex].Value; 

                        var category = ctx.Categories.First(p => p.CategoryID == categoryId); 

                        // 加载类别下的产品到当前上下文中，用以级联删除 
                        // 当然如果在数据库中配置了级联删除，并且映射中配置了<OnDelete Action= "Cascade" />（EDM编辑器会根据数据库中的配置自动做此配置）则不用此句 
                        category.Products.Load(); 

                        // DeleteObject() - 将指定的对象的状态更改为已删除（调用 SaveChanges() 之后才会执行） 
                        ctx.DeleteObject(category); 

                        ctx.SaveChanges(); 
                } 

                GridView1.EditIndex = -1; 
                BindData(); 
        } 

void GridView1_SelectedIndexChanged() void GridView1_SelectedIndexChanged(object sender, EventArgs e) 
        { 
                using (var ctx =  new NorthwindEntities()) 
                { 
                        var categoryId = (int)GridView1.SelectedDataKey.Value; 

                        // 查找当前选中的类别下的产品集合 
                        var products = ctx.Products.Where(p => p.Categories.CategoryID == categoryId); 

                        // 将 System.Linq.IQueryable<Products> 绑定到 GridView2 
                        GridView2.DataSource = products; 
                        GridView2.DataBind(); 
                } 
        } 

void GridView1_RowUpdating() void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e) 
        { 
                using (var ctx =  new NorthwindEntities()) 
                { 
                        var categoryId = (int)GridView1.DataKeys[e.RowIndex].Value; 

                        var category = ctx.Categories.First(p => p.CategoryID == categoryId); 

                        // 修改 category 对象的属性 
                        category.CategoryName = ((TextBox)GridView1.Rows[e.RowIndex].Cells[1].Controls[0]).Text; 
                        category.Description = ((TextBox)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).Text; 

                        ctx.SaveChanges(); 
                } 

                GridView1.EditIndex = -1; 
                BindData(); 
        } 

void GridView1_RowEditing() void GridView1_RowEditing(object sender, GridViewEditEventArgs e) 
        { 
                GridView1.EditIndex = e.NewEditIndex; 
                BindData(); 
        } 

void GridView1_RowCancelingEdit() void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e) 
        { 
                GridView1.EditIndex = -1; 
                BindData(); 
        } 
}