ObjectDataSourceFilteringEventHandler 委托

定义

表示将处理 Filtering 控件的 ObjectDataSource 事件的方法。Represents the method that will handle the Filtering event of the ObjectDataSource control.

public delegate void ObjectDataSourceFilteringEventHandler(System::Object ^ sender, ObjectDataSourceFilteringEventArgs ^ e);
public delegate void ObjectDataSourceFilteringEventHandler(object sender, ObjectDataSourceFilteringEventArgs e);
type ObjectDataSourceFilteringEventHandler = delegate of obj * ObjectDataSourceFilteringEventArgs -> unit
Public Delegate Sub ObjectDataSourceFilteringEventHandler(sender As Object, e As ObjectDataSourceFilteringEventArgs)

参数

sender
Object

事件的源,即 ObjectDataSourceThe source of the event, the ObjectDataSource.

继承
ObjectDataSourceFilteringEventHandler

示例

本部分包含两个代码示例。This section contains two code examples. 第一个代码示例演示如何使用ObjectDataSource控件从中间层业务对象中检索数据, 然后GridView使用控件显示结果, 从而显示筛选后的数据。The first code example demonstrates how to display filtered data by using an ObjectDataSource control to retrieve data from a middle-tier business object, and then using a GridView control to display the results. 第二个代码示例提供了第一个代码示例使用的中间层业务对象的示例。The second code example provides an example of a middle-tier business object that is used by the first code example.

下面的代码示例演示如何使用ObjectDataSource控件从中间层业务对象中检索数据, 然后GridView使用控件显示结果, 从而显示筛选后的数据。The following code example demonstrates how to display filtered data by using an ObjectDataSource control to retrieve data from a middle-tier business object, and then using a GridView control to display the results. 仅当检索数据的方法将其检索DataSet为或DataTable对象时,控件才能筛选数据。ObjectDataSourceThe ObjectDataSource control can filter data only when the method that retrieves the data retrieves it as a DataSet or DataTable object. 出于此原因, SelectMethod属性标识将数据DataSet作为或DataTable对象检索的业务对象方法。For this reason, the SelectMethod property identifies a business object method that retrieves data as a DataSet or DataTable object.

TextBox代码示例包含一个控件、一个GridView控件、 ObjectDataSource一个控件和一个提交按钮。The code example consists of a TextBox control, a GridView control, the ObjectDataSource control, and a Submit button. 默认情况下, TextBox该控件用 Northwind 商贸中某个雇员的名称填充。By default, the TextBox control is populated with the name of one of the employees at Northwind Traders. 控件在中显示由名称标识的员工的相关信息。 TextBox GridViewThe GridView control displays information about the employee who is identified by the name in the TextBox. 若要检索另一个雇员的数据, TextBox请在控件中键入雇员的全名, 然后单击 "提交" 按钮。To retrieve data for another employee, in the TextBox control, type the full name of the employee, and then click the Submit button.

属性指定一个表达式, 该表达式用于筛选由SelectMethod属性指定的方法检索的数据。 FilterExpressionThe FilterExpression property specifies an expression that is used to filter the data that is retrieved by the method that is specified by the SelectMethod property. 它使用计算结果为FilterParameters集合中包含的参数的参数占位符。It uses parameter placeholders that are evaluated to the parameters that are contained in the FilterParameters collection. 在此示例中, 参数占位符括在单引号 (') 中, 因为该参数的类型是可能包含空格的字符串类型。In this example, the parameter placeholder is enclosed by single quotation marks (') because the type of the parameter is a string type that might contain spaces. 如果参数的类型为数值或日期, 则不需要引号。If the type of the parameter is numeric or date, quotation marks are not required. 集合包含一个参数FormParameter , TextBox该对象绑定到控件。 FilterParametersThe FilterParameters collection contains one parameter, a FormParameter object that is bound to the TextBox control.

如果未在TextBox控件中指定任何名称, 则会将一个新参数添加ParameterValues到集合中, 以便搜索成功。If no name is specified in the TextBox control, a new parameter is added to the ParameterValues collection so that the search is successful.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS" Assembly="Samples.AspNet.CS" %>
<%@ Page language="c#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

    protected void ObjectDataSource1_Filtering(object sender, ObjectDataSourceFilteringEventArgs e)
    {
        if (Textbox1.Text == "")
        {
            e.ParameterValues.Clear();
            e.ParameterValues.Add("FullName", "Nancy Davolio");
        }
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <p>Show all users with the following name.</p>

        <asp:textbox id="Textbox1" runat="server" text="Nancy Davolio" />

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1"
          autogeneratecolumns="False">
          <columns>
            <asp:boundfield headertext="ID" datafield="EmpID" />
            <asp:boundfield headertext="Name" datafield="FullName" />
            <asp:boundfield headertext="Street Address" datafield="Address" />
          </columns>
        </asp:gridview>

        <!-- Security Note: The ObjectDataSource uses a FormParameter,
             Security Note: which does not perform validation of input from the client. -->

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployeesAsDataSet"
          typename="Samples.AspNet.CS.EmployeeLogic"
          filterexpression="FullName='{0}'" OnFiltering="ObjectDataSource1_Filtering">
            <filterparameters>
              <asp:formparameter name="FullName" formfield="Textbox1" defaultvalue="Nancy Davolio" />
            </filterparameters>
        </asp:objectdatasource>

        <p><asp:button id="Button1" runat="server" text="Search" /></p>

    </form>
  </body>
</html>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB" Assembly="Samples.AspNet.VB" %>
<%@ Page language="vb" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

    Protected Sub ObjectDataSource1_Filtering(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ObjectDataSourceFilteringEventArgs)
        If Textbox1.Text = "" Then
            e.ParameterValues.Clear()
            e.ParameterValues.Add("FullName", "Nancy Davolio")
        End If
    End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - VB Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <p>Show all users with the following name.</p>

        <asp:textbox id="Textbox1" runat="server" text="Nancy Davolio" />

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1"
          autogeneratecolumns="False">
          <columns>
            <asp:boundfield headertext="ID" datafield="EmpID" />
            <asp:boundfield headertext="Name" datafield="FullName" />
            <asp:boundfield headertext="Street Address" datafield="Address" />
          </columns>
        </asp:gridview>

        <!-- Security Note: The ObjectDataSource uses a FormParameter,
             Security Note: which does not perform validation of input from the client. -->

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployeesAsDataSet"
          typename="Samples.AspNet.VB.EmployeeLogic"
          filterexpression="FullName='{0}'" OnFiltering="ObjectDataSource1_Filtering">
            <filterparameters>
              <asp:formparameter name="FullName" formfield="Textbox1" defaultvalue="Nancy Davolio" />
            </filterparameters>
        </asp:objectdatasource>

        <p><asp:button id="Button1" runat="server" text="Search" /></p>

    </form>
  </body>
</html>

下面的代码示例提供了前面的代码示例使用的中间层业务对象的示例。The following code example provides an example of a middle-tier business object that the preceding code example uses. 此代码示例包含两个基本类: EmployeeLogicNorthwindEmployeeThe code example consists of two basic classes: EmployeeLogic and NorthwindEmployee. 类封装业务逻辑NorthwindEmployee , 类是一个模型类, 该类仅包含从数据层加载和保存数据所需的基本功能。 EmployeeLogicThe EmployeeLogic class encapsulates business logic and the NorthwindEmployee class is a model class that contains only the basic functionality that is required to load and persist data from the data tier. 为简单起见, EmployeeLogic类创建了静态数据集, 而不是从数据层检索数据。For simplicity, the EmployeeLogic class creates a static set of data, rather than retrieving the data from a data tier. 对于完整的工作示例, 必须使用所提供的 Web 窗体代码示例来编译并使用这些类。For a complete working example, you must compile and use these classes with the Web Forms code examples that are provided.

namespace Samples.AspNet.CS {

using System;
using System.Collections;
using System.Data;
using System.Web.UI.WebControls;
  //
  // EmployeeLogic is a stateless business object that encapsulates 
  // the operations you can perform on a NorthwindEmployee object.
  //
  public class EmployeeLogic {
  
    
    // Returns a collection of NorthwindEmployee objects.
    public static ICollection GetAllEmployees () {
      ArrayList data = new ArrayList();
           
      data.Add(new NorthwindEmployee(1,"Nancy","Davolio","507 - 20th Ave. E. Apt. 2A"));
      data.Add(new NorthwindEmployee(2,"Andrew","Fuller","908 W. Capital Way"));
      data.Add(new NorthwindEmployee(3,"Janet","Leverling","722 Moss Bay Blvd."));
      data.Add(new NorthwindEmployee(4,"Margaret","Peacock","4110 Old Redmond Rd."));
      data.Add(new NorthwindEmployee(5,"Steven","Buchanan","14 Garrett Hill"));
      data.Add(new NorthwindEmployee(6,"Michael","Suyama","Coventry House Miner Rd."));
      data.Add(new NorthwindEmployee(7,"Robert","King","Edgeham Hollow Winchester Way"));
      
      return data;
    }
    
    public static NorthwindEmployee GetEmployee(object anID) {
      ArrayList data = GetAllEmployees() as ArrayList;     
      int empID = Int32.Parse(anID.ToString());      
      return data[empID] as NorthwindEmployee;
    }

    // 
    // To support basic filtering, the employees cannot
    // be returned as an array of objects, rather as a 
    // DataSet of the raw data values. 
    public static DataSet GetAllEmployeesAsDataSet () {
      ICollection employees = GetAllEmployees();
      
      DataSet ds = new DataSet("Table");
      
      // Create the schema of the DataTable.
      DataTable dt = new DataTable();
      DataColumn dc;
      dc = new DataColumn("EmpID",   typeof(int));    dt.Columns.Add(dc);
      dc = new DataColumn("FullName",typeof(string)); dt.Columns.Add(dc);
      dc = new DataColumn("Address", typeof(string)); dt.Columns.Add(dc);
      
      // Add rows to the DataTable.
      DataRow row;
            
      foreach (NorthwindEmployee ne in employees) {                
        row = dt.NewRow();
        row["EmpID"]    = ne.EmpID;
        row["FullName"] = ne.FullName;
        row["Address"]  = ne.Address;
        dt.Rows.Add(row);
      } 
      // Add the complete DataTable to the DataSet.
      ds.Tables.Add(dt);
      
      return ds;
    }    
  }

  public class NorthwindEmployee {

    public NorthwindEmployee (int anID, 
                              string aFirstName,
                              string aLastName,
                              string anAddress) {
      ID = anID;
      firstName = aFirstName;
      lastName = aLastName;   
      address = anAddress;
    }

    private object ID;
    public string EmpID {
      get { return ID.ToString();  }
    }

    private string lastName;
    public string LastName {
      get { return lastName; }
      set { lastName = value; }
    }

    private string firstName;
    public string FirstName {
      get { return firstName; }
      set { firstName = value;  }
    }
    
    public string FullName {
      get { return FirstName  + " " +  LastName; }
    }
    
    private string address;
    public string Address {
      get { return address; }
      set { address = value;  }
    }    
    
  }
}
Imports System.Collections
Imports System.Data
Imports System.Web.UI.WebControls

Namespace Samples.AspNet.VB
'
' EmployeeLogic is a stateless business object that encapsulates 
' the operations you can perform on a NorthwindEmployee object.
'
Public Class EmployeeLogic
   
   ' Returns a collection of NorthwindEmployee objects.
   Public Shared Function GetAllEmployees() As ICollection
      Dim data As New ArrayList()
      
      data.Add(New NorthwindEmployee(1, "Nancy", "Davolio", "507 - 20th Ave. E. Apt. 2A"))
      data.Add(New NorthwindEmployee(2, "Andrew", "Fuller", "908 W. Capital Way"))
      data.Add(New NorthwindEmployee(3, "Janet", "Leverling", "722 Moss Bay Blvd."))
      data.Add(New NorthwindEmployee(4, "Margaret", "Peacock", "4110 Old Redmond Rd."))
      data.Add(New NorthwindEmployee(5, "Steven", "Buchanan", "14 Garrett Hill"))
      data.Add(New NorthwindEmployee(6, "Michael", "Suyama", "Coventry House Miner Rd."))
      data.Add(New NorthwindEmployee(7, "Robert", "King", "Edgeham Hollow Winchester Way"))
      
      Return data
   End Function 'GetAllEmployees
   
   
   Public Shared Function GetEmployee(anID As Object) As NorthwindEmployee
      Dim data As ArrayList = CType(GetAllEmployees(), ArrayList)
      Dim empID As Integer = Int32.Parse(anID.ToString())
      Return CType(data(empID),NorthwindEmployee)   
   End Function 'GetEmployee
   
   
   ' To support basic filtering, the employees cannot
   ' be returned as an array of objects, rather as a 
   ' DataSet of the raw data values. 
   Public Shared Function GetAllEmployeesAsDataSet() As DataSet
      Dim employees As ICollection = GetAllEmployees()
      
      Dim ds As New DataSet("Table")
      
      ' Create the schema of the DataTable.
      Dim dt As New DataTable()
      Dim dc As DataColumn
      dc = New DataColumn("EmpID", GetType(Integer))
      dt.Columns.Add(dc)
      dc = New DataColumn("FullName", GetType(String))
      dt.Columns.Add(dc)
      dc = New DataColumn("Address", GetType(String))
      dt.Columns.Add(dc)
      
      ' Add rows to the DataTable.
      Dim row As DataRow
      Dim ne As NorthwindEmployee
      For Each ne In employees         
         row = dt.NewRow()
         row("EmpID") = ne.EmpID
         row("FullName") = ne.FullName
         row("Address") = ne.Address
         dt.Rows.Add(row)
      Next
      ' Add the complete DataTable to the DataSet.
      ds.Tables.Add(dt)
      
      Return ds
   End Function 'GetAllEmployeesAsDataSet
      
End Class


Public Class NorthwindEmployee
   
   Public Sub New(anID As Integer, aFirstName As String, aLastName As String, anAddress As String)
      ID = anID
      Me.aFirstName = aFirstName
      Me.aLastName = aLastName
      Me.aAddress = anAddress
   End Sub
   
   Private ID As Object   
   Public ReadOnly Property EmpID() As String
      Get
         Return ID.ToString()
      End Get
   End Property 

   Private aLastName As String   
   Public Property LastName() As String
      Get
         Return aLastName
      End Get
      Set
         aLastName = value
      End Set
   End Property 

   Private aFirstName As String   
   Public Property FirstName() As String
      Get
         Return aFirstName
      End Get
      Set
         aFirstName = value
      End Set
   End Property 
   
   Public ReadOnly Property FullName() As String
      Get
         Return FirstName & " " & LastName
      End Get
   End Property 
  
   Private aAddress As String  
   Public Property Address() As String
      Get
         Return aAddress
      End Get
      Set
         aAddress = value
      End Set
   End Property 
   
End Class
End Namespace

注解

创建 ObjectDataSourceFilteringEventHandler 委托时,需要标识将要处理该事件的方法。When you create an ObjectDataSourceFilteringEventHandler delegate, you identify the method that will handle the event. 若要将事件与事件处理程序关联,请将该委托的一个实例添加到事件中。To associate the event with your event handler, add an instance of the delegate to the event. 除非移除了该委托,否则每当发生该事件时就会调用事件处理程序。The event handler is called whenever the event occurs, unless you remove the delegate. 有关如何处理事件的详细信息, 请参阅处理和引发事件For more information about how to handle events, see Handling and Raising Events.

扩展方法

GetMethodInfo(Delegate)

获取指示指定委托表示的方法的对象。Gets an object that represents the method represented by the specified delegate.

适用于

另请参阅