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


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);
        }
}