温故知新ASP.NET 2.0(C#)(8) - DataSourceControl(数据源控件)

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[align=center]温故知新ASP.NET 2.0(C#)(8) - DataSourceControl(数据源控件)[/align]

作者：webabcd

介绍
在 ASP.NET 2.0 中有几个新的数据源控件，例如，SqlDataSource、ObjectDataSource、XmlDataSource、AccessDataSource 和 SiteMapDataSource。它们全都可以用来从它们各自类型的数据源中检索数据，并且可以绑定到各种数据绑定控件。数据源控件减少了为检索和绑定数据甚至对数据进行排序、分页或编辑而需要编写的自定义代码的数量。

其中 ObjectDataSource 控件可针对各种基础数据存储区（如 SQL 数据库或 XML）启用声明性数据绑定模型。因为页开发人员也常常将数据检索（也可能包含业务逻辑）封装在一个组件对象中，从而在呈现页和数据提供程序之间引入另一个层。ObjectDataSource 控件允许开发人员使用此传统的三层结构构造应用程序，同时仍然能够利用 ASP.NET 中的声明性数据绑定模型的易用性优点。

关键
1、在数据层创建 强类型的DataSet和TableAdapter，TableAdapter查询可以使用现有的存储过程。注：直接把表或存储过程拖进来会自动创建TableAdapter

2、中间层的类用[System.ComponentModel.DataObject]声明为数据组件，CRUD方法分别对应[DataObjectMethod(DataObjectMethodType.Insert)]，[DataObjectMethod(DataObjectMethodType.Select)]，[DataObjectMethod(DataObjectMethodType.Update)]，[DataObjectMethod(DataObjectMethodType.Delete)]

3、web层使用ObjectDataSource展现数据，ObjectDataSource就相当于一个代理。ObjectDataSource只是查找具有匹配的参数名称的方法，它不会使用参数的 Type 或 Size，而只是对参数的名称进行匹配

4、其它
·<asp:Parameter />有ConvertEmptyStringToNull属性，默认是true。另外还有Direction属性
·注意<asp:BoundField />的这几个属性NullDisplayText，HtmlEncode，ApplyFormatInEditMode，InsertVisible，DataFormatString，ReadOnly
·DataKeyNames有多个值的话用“,”分隔，用<asp:ControlParameter />绑定的话给其加一个“PropertyName”属性，值类似如下“SelectedDataKey.Values[0]”
·关于绑定：简单属性<%# custID %>；集合<asp:ListBox id="List1" datasource='<%# myArray %>' runat="server">；表达式<%# ( customer.FirstName + " " + customer.LastName ) %>；方法<%# GetBalance(custID) %>
·<%# Eval("field1") %> 和 <%# Bind("field1") %>，Eval是单向绑定，Bind是双向邦定
·<asp:ObjectDataSource />有一个OldValuesParameterFormatString属性一般不用，不过如果要处理乐观并发之类的就会用到。当该属性的值为“original_{0}”的时候“original_参数名”则为初始值
·还有一些如编程方式给参数赋值，错误处理，得到返回值之类的请看源码

示例
相关存储过程和数据层略，见源码

单例模式的实现
App_Code/Singleton.cs


using System;


using System.Data;


using System.Configuration;


using System.Web;


using System.Web.Security;


using System.Web.UI;


using System.Web.UI.WebControls;


using System.Web.UI.WebControls.WebParts;


using System.Web.UI.HtmlControls;



/// <summary>
/// Singleton 的摘要说明
/// </summary>


public class Singleton<T> where T : new()


{


public static T Instance


{


get { return SingletonCreator.instance; }


}




class SingletonCreator


{


internal static readonly T instance = new T();


}


}

中间层代码
App_Code/Test.cs


using System;


using System.Data;


using System.Configuration;


using System.Web;


using System.Web.Security;


using System.Web.UI;


using System.Web.UI.WebControls;


using System.Web.UI.WebControls.WebParts;


using System.Web.UI.HtmlControls;




using TestDatabaseTableAdapters;


using System.ComponentModel;



/// <summary>
/// Test 的摘要说明
/// </summary>


[DataObject]


public class Test


{


[DataObjectMethod(DataObjectMethodType.Select, true)]


public TestDatabase.TestDataTable GetTest()


{


return Singleton<TestTableAdapter>.Instance.GetTest();


}




[DataObjectMethod(DataObjectMethodType.Select, false)]


public TestDatabase.TestDataTable GetTestById(int id)


{


return Singleton<TestTableAdapter>.Instance.GetTestById(id);


}




[DataObjectMethod(DataObjectMethodType.Insert, true)]


public int?[] InsertTest(int? parentId, string name, DateTime? publishTime, decimal? price, bool? isGood, out int? minId)


{


// 仅为说明如何做错误处理


if (String.IsNullOrEmpty(name))


throw new ArgumentException("参数不能是空", "name");




int? id = null;


int? count = null;


minId = null;




Singleton<TestTableAdapter>.Instance.InsertTest(parentId, name, publishTime, price, isGood, ref id, ref count, ref minId);


return new int?[] { id, count };


}




[DataObjectMethod(DataObjectMethodType.Delete, true)]


public int? DeleteTest(int id)


{


int? rowAffected;




rowAffected = Singleton<TestTableAdapter>.Instance.DeleteTest(id);


return rowAffected;


}




[DataObjectMethod(DataObjectMethodType.Update, true)]


public int? UpdateTest(int? id, int? parentId, string name, DateTime? publishTime, decimal? price, bool? isGood)


{


int? rowAffected;




rowAffected = Singleton<TestTableAdapter>.Instance.UpdateTest(id, parentId, name, publishTime, price, isGood);


return rowAffected;


}


}

DataSourceControl/Test.aspx

<%@ Page Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile="Test.aspx.cs"
Inherits="DataSourceControl_Test" Title="数据源控件测试" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
<p>
<asp:Label ID="lblMsg" runat="server" ForeColor="red" />
</p>
<table cellpadding="6">
<tr>
<td valign="top">
<asp:DetailsView ID="DetailsView1" runat="server" AllowPaging="True" AutoGenerateRows="False"
DataKeyNames="Id" DataSourceID="ObjectDataSource1" Height="50px" Width="125px" OnItemInserted="DetailsView1_ItemInserted">
<Fields>
<asp:BoundField DataField="Id" HeaderText="Id" InsertVisible="False" ReadOnly="True"
SortExpression="Id" />
<asp:BoundField DataField="ParentId" HeaderText="ParentId" SortExpression="ParentId" />
<asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
<asp:BoundField DataField="PublishTime" HeaderText="PublishTime" SortExpression="PublishTime"
InsertVisible="False" />
<asp:BoundField DataField="Price" HeaderText="Price" SortExpression="Price" DataFormatString="{0:c}" HtmlEncode="False" />
<asp:CheckBoxField DataField="IsGood" HeaderText="IsGood" SortExpression="IsGood" />
<asp:CommandField ShowInsertButton="True" />
</Fields>
</asp:DetailsView>
</td>
<td valign="top">
<asp:DetailsView ID="DetailsView2" runat="server" Height="50px" Width="125px" AutoGenerateRows="False" DataKeyNames="Id" DataSourceID="ObjectDataSource2">
<Fields>
<asp:BoundField DataField="Id" HeaderText="Id" InsertVisible="False" ReadOnly="True"
SortExpression="Id" />
<asp:BoundField DataField="ParentId" HeaderText="ParentId" SortExpression="ParentId" />
<asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
<asp:BoundField DataField="PublishTime" HeaderText="PublishTime" SortExpression="PublishTime" />
<asp:BoundField DataField="Price" HeaderText="Price" SortExpression="Price" DataFormatString="{0:c}" HtmlEncode="false" />
<asp:CheckBoxField DataField="IsGood" HeaderText="IsGood" SortExpression="IsGood" />
</Fields>
</asp:DetailsView>
</td>
</tr>
</table>
<p>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="Id"
DataSourceID="ObjectDataSource1" AllowPaging="True" AllowSorting="True" OnRowUpdating="GridView1_RowUpdating">
<Columns>
<asp:CommandField ShowDeleteButton="True" ShowEditButton="True" ShowSelectButton="True" />
<asp:BoundField DataField="Id" HeaderText="Id" InsertVisible="False" ReadOnly="True"
SortExpression="Id" />
<asp:BoundField DataField="ParentId" HeaderText="ParentId" SortExpression="ParentId"
NullDisplayText="我的值是NULL" />
<asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
<asp:BoundField DataField="PublishTime" HeaderText="PublishTime" SortExpression="PublishTime"
ReadOnly="true" />
<asp:BoundField DataField="Price" HeaderText="Price" SortExpression="Price" DataFormatString="{0:c}" HtmlEncode="false" ApplyFormatInEditMode="True" />
<asp:CheckBoxField DataField="IsGood" HeaderText="IsGood" SortExpression="IsGood" />
</Columns>
</asp:GridView>
</p>
<asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="GetTest"
TypeName="Test" InsertMethod="InsertTest" DeleteMethod="DeleteTest" UpdateMethod="UpdateTest"
OnInserting="ObjectDataSource1_Inserting" OnInserted="ObjectDataSource1_Inserted">
<InsertParameters>
<%--ConvertEmptyStringToNull属性默认为true--%>
<asp:Parameter Name="parentId" Type="Int32" ConvertEmptyStringToNull="true" />
<asp:Parameter Name="name" Type="String" />
<asp:Parameter Name="publishTime" Type="DateTime" />
<asp:Parameter Name="price" Type="Decimal" />
<asp:Parameter Name="isGood" Type="Boolean" />
<asp:Parameter Direction="Output" Name="minId" Type="Int32" />
</InsertParameters>
<DeleteParameters>
<asp:Parameter Name="id" Type="Int32" />
</DeleteParameters>
<UpdateParameters>
<asp:Parameter Name="id" Type="Int32" />
<asp:Parameter Name="parentId" Type="Int32" />
<asp:Parameter Name="name" Type="String" />
<asp:Parameter Name="publishTime" Type="DateTime" />
<asp:Parameter Name="price" Type="Decimal" />
<asp:Parameter Name="isGood" Type="Boolean" />
</UpdateParameters>
</asp:ObjectDataSource>
<asp:ObjectDataSource ID="ObjectDataSource2" runat="server" OldValuesParameterFormatString="original_{0}"
SelectMethod="GetTestById" TypeName="Test">
<SelectParameters>
<asp:ControlParameter ControlID="GridView1" Name="id" PropertyName="SelectedValue"
Type="Int32" />
</SelectParameters>
</asp:ObjectDataSource>
</asp:Content>

DataSourceControl/Test.aspx.cs


using System;


using System.Data;


using System.Configuration;


using System.Collections;


using System.Web;


using System.Web.Security;


using System.Web.UI;


using System.Web.UI.WebControls;


using System.Web.UI.WebControls.WebParts;


using System.Web.UI.HtmlControls;




public partial class DataSourceControl_Test : System.Web.UI.Page


{


protected void Page_Load(object sender, EventArgs e)


{




}




protected void ObjectDataSource1_Inserting(object sender, ObjectDataSourceMethodEventArgs e)


{


// 编程方式给参数赋值


if (e.InputParameters["publishTime"] == null)


{


e.InputParameters["publishTime"] = DateTime.Now;


}


}




protected void ObjectDataSource1_Inserted(object sender, ObjectDataSourceStatusEventArgs e)


{


// 错误处理


if (e.Exception != null)


{


if (e.Exception.InnerException != null)


{


Exception inner = e.Exception.InnerException;




if (inner is ArgumentException)


{


string paramName = ((ArgumentException)inner).ParamName;


lblMsg.Text = string.Concat("参数 ", paramName, " 有问题");


}


}


}


else


{


int?[] ary = (int?[])e.ReturnValue;


lblMsg.Text = "新插入信息的ID是：" + ary[0].ToString();


lblMsg.Text += "<br />数据总数是：" + ary[1].ToString();




lblMsg.Text += "<br />最小ID是：" + e.OutputParameters["minId"].ToString();


}


}




protected void DetailsView1_ItemInserted(object sender, DetailsViewInsertedEventArgs e)


{


if (e.Exception != null)


{


// 错误已处理


e.ExceptionHandled = true;


// DetailsView保持插入状态


e.KeepInInsertMode = true;


}


}




protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)


{


// 价格格式转换为decimal格式


if (e.NewValues["Price"] != null)


e.NewValues["Price"] = decimal.Parse(e.NewValues["Price"].ToString(), System.Globalization.NumberStyles.Currency);


}


}

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