重新过一遍ASP.NET 2.0(C#)(8) DataSourceControl(数据源控件)

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，客户<%# custID %> ；集合，订单<asp:ListBox id="List1" datasource='<%# myArray %>' runat="server">；表达式， 合同<%# ( customer.FirstName + " " + customer.LastName ) %>；方法结果，未结余额<%# 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);
    }
}

OK
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