ObjectDataSource.Deleted 事件

定义

Delete() 操作完成时发生。Occurs when a Delete() operation has completed.

public:
 event System::Web::UI::WebControls::ObjectDataSourceStatusEventHandler ^ Deleted;
public event System.Web.UI.WebControls.ObjectDataSourceStatusEventHandler Deleted;
member this.Deleted : System.Web.UI.WebControls.ObjectDataSourceStatusEventHandler 
Public Custom Event Deleted As ObjectDataSourceStatusEventHandler 

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将ObjectDataSource对象与业务对象GridView和控件结合使用来删除数据。The first code example demonstrates how to use an ObjectDataSource object with a business object and a GridView control to delete data. 第二个代码示例演示EmployeeLogic了第一个代码示例中使用的类。The second code example shows the EmployeeLogic class that is used in the first code example.

下面的代码示例演示如何将ObjectDataSource控件与业务对象GridView和控件结合使用来删除数据。The following code example demonstrates how to use an ObjectDataSource control with a business object and a GridView control to delete data. 最初, GridView控件使用SelectMethod由属性指定的方法来显示EmployeeLogic对象中的数据, 以显示一组所有雇员。Initially, the GridView control displays a set of all employees, using the method that is specified by the SelectMethod property to retrieve the data from the EmployeeLogic object. 由于属性设置为true, 因此该控件会GridView自动显示 "删除" 按钮。 AutoGenerateDeleteButtonBecause the AutoGenerateDeleteButton property is set to true, the GridView control automatically displays a Delete button.

如果单击 "删除" 按钮, 则将使用DeleteMethod属性指定的方法和DeleteParameters集合中指定的任何参数来执行删除操作。If you click the Delete button, the delete operation is performed using the method that is specified by the DeleteMethod property and any parameters that are specified in the DeleteParameters collection. 在此代码示例中, 还执行了一些预处理和后处理步骤。In this code example, some preprocessing and post-processing steps are also performed. NorthwindEmployeeDeleting执行操作之前调用委托来Deleting处理事件, 并在NorthwindEmployeeDeleted操作完成后调用委托来处理Deleted事件以执行异常处理。The NorthwindEmployeeDeleting delegate is called to handle the Deleting event before the operation is performed and the NorthwindEmployeeDeleted delegate is called to handle the Deleted event after the operation has completed to perform exception handling. 在此代码示例中, 如果NorthwindDataException引发了, 则NorthwindEmployeeDeleted由方法进行处理。In this code example, if a NorthwindDataException is thrown, it is handled by the NorthwindEmployeeDeleted method.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS" Assembly="Samples.AspNet.CS" %>
<%@ Import namespace="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">
private void NorthwindEmployeeDeleting(object source, ObjectDataSourceMethodEventArgs e)
{
  // The GridView passes the ID of the employee
  // to be deleted. However, the buisiness object, EmployeeLogic,
  // requires a NorthwindEmployee parameter, named "ne". Create
  // it now and add it to the parameters collection.
  IDictionary paramsFromPage = e.InputParameters;
  if (paramsFromPage["EmpID"] != null) {
    NorthwindEmployee ne
      = new NorthwindEmployee( Int32.Parse(paramsFromPage["EmpID"].ToString()));
    // Remove the old EmpID parameter.
    paramsFromPage.Clear();
    paramsFromPage.Add("ne", ne);
  }
}

private void NorthwindEmployeeDeleted(object source, ObjectDataSourceStatusEventArgs e)
{
  // Handle the Exception if it is a NorthwindDataException
  if (e.Exception != null)
  {

    // Handle the specific exception type. The ObjectDataSource wraps
    // any Exceptions in a TargetInvokationException wrapper, so
    // check the InnerException property for expected Exception types.
    if (e.Exception.InnerException is NorthwindDataException)
    {
      Label1.Text = e.Exception.InnerException.Message;
      // Because the exception is handled, there is
      // no reason to throw it.
      e.ExceptionHandled = true;
    }
  }
}

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

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1"
          autogeneratedeletebutton="true"
          autogeneratecolumns="false"
          datakeynames="EmpID">
          <columns>
            <asp:boundfield headertext="EmpID" datafield="EmpID" />
            <asp:boundfield headertext="First Name" datafield="FirstName" />
            <asp:boundfield headertext="Last Name" datafield="LastName" />
          </columns>
        </asp:gridview>

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          deletemethod="DeleteEmployee"
          ondeleting="NorthwindEmployeeDeleting"
          ondeleted="NorthwindEmployeeDeleted"
          typename="Samples.AspNet.CS.EmployeeLogic">
          <deleteparameters>
            <asp:parameter name="EmpID" type="Int32" />
          </deleteparameters>
        </asp:objectdatasource>

        <asp:label id="Label1" runat="server" />

    </form>
  </body>
</html>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB" Assembly="Samples.AspNet.VB" %>
<%@ Import namespace="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">
' Called before a Delete operation.
    Private Sub NorthwindEmployeeDeleting(ByVal source As Object, ByVal e As ObjectDataSourceMethodEventArgs)

        ' The GridView passes the ID of the employee
        ' to be deleted. However, the business object, EmployeeLogic,
        ' requires a NorthwindEmployee parameter, named "ne". Create
        ' it now and add it to the parameters collection.
        Dim paramsFromPage As IDictionary = e.InputParameters
  
        If Not paramsFromPage("EmpID") Is Nothing Then
    
            Dim ne As New NorthwindEmployee(paramsFromPage("EmpID").ToString())
            ' Remove the old EmpID parameter.
            paramsFromPage.Clear()
            paramsFromPage.Add("ne", ne)
    
    
        End If
    End Sub ' NorthwindEmployeeDeleting

    ' Called after a Delete operation.
    Private Sub NorthwindEmployeeDeleted(ByVal source As Object, ByVal e As ObjectDataSourceStatusEventArgs)
        ' Handle the Exception if it is a NorthwindDataException.
        If Not e.Exception Is Nothing Then

            ' Handle the specific exception type. The ObjectDataSource wraps
            ' any Exceptions in a TargetInvokationException wrapper, so
            ' check the InnerException property for the expected Exception types.
            If e.Exception.InnerException.GetType().Equals(GetType(NorthwindDataException)) Then

                Label1.Text = e.Exception.InnerException.Message
                ' Because the exception is handled, there is
                ' no reason to throw it.
                e.ExceptionHandled = True
      
            End If
        End If
    End Sub ' NorthwindEmployeeDeleted
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - VB Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1"
          autogeneratedeletebutton="true"
          autogeneratecolumns="false"
          datakeynames="EmpID">
          <columns>
            <asp:boundfield headertext="EmpID" datafield="EmpID" />
            <asp:boundfield headertext="First Name" datafield="FirstName" />
            <asp:boundfield headertext="Last Name" datafield="LastName" />
          </columns>
        </asp:gridview>

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          deletemethod="DeleteEmployee"
          ondeleting="NorthwindEmployeeDeleting"
          ondeleted="NorthwindEmployeeDeleted"
          typename="Samples.AspNet.VB.EmployeeLogic">
          <deleteparameters>
            <asp:parameter name="EmpID" type="Int32" />
          </deleteparameters>
        </asp:objectdatasource>

        <asp:label id="Label1" runat="server" />

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

下面的代码示例演示EmployeeLogic了前面的代码示例中使用的类。The following code example shows the EmployeeLogic class that is used in the preceding code example.

namespace Samples.AspNet.CS {

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Web.UI;
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 al = new ArrayList();

      // Use the SqlDataSource class to wrap the
      // ADO.NET code required to query the database.
      ConnectionStringSettings cts = ConfigurationManager.ConnectionStrings["NorthwindConnection"];

      SqlDataSource sds
        = new SqlDataSource(cts.ConnectionString,
                            "SELECT EmployeeID FROM Employees");
      try {
        IEnumerable IDs = sds.Select(DataSourceSelectArguments.Empty);

        // Iterate through the Enumeration and create a
        // NorthwindEmployee object for each ID.
        IEnumerator enumerator = IDs.GetEnumerator();
        while (enumerator.MoveNext()) {
          // The IEnumerable contains DataRowView objects.
          DataRowView row = enumerator.Current as DataRowView;
          string id = row["EmployeeID"].ToString();
          NorthwindEmployee nwe = new NorthwindEmployee(id);
          // Add the NorthwindEmployee object to the collection.
          al.Add(nwe);
        }
      }
      finally {
        // If anything strange happens, clean up.
        sds.Dispose();
      }

      return al;
    }

    public static NorthwindEmployee GetEmployee(object anID) {
      return new NorthwindEmployee(anID);
    }

    public static void DeleteEmployee(NorthwindEmployee ne) {
      bool retval = ne.Delete();
      if (! retval) { throw new NorthwindDataException("Employee delete failed."); }
      // Delete the object in memory.
      ne = null;
    }

    public static void DeleteEmployeeByID(int anID) {
        NorthwindEmployee tempEmp = new NorthwindEmployee(anID);
        DeleteEmployee(tempEmp);
    }
  }

  public class NorthwindEmployee {

    public NorthwindEmployee () {
      ID = DBNull.Value;
      lastName = "";
      firstName = "";
    }

    public NorthwindEmployee (object anID) {
      this.ID = anID;

      ConnectionStringSettings cts = ConfigurationManager.ConnectionStrings["NorthwindConnection"];

      SqlConnection conn = new SqlConnection (cts.ConnectionString);
      SqlCommand sc =
        new SqlCommand(" SELECT FirstName,LastName " +
                       " FROM Employees " +
                       " WHERE EmployeeID = @empId",
                       conn);
      // Add the employee ID parameter and set its value.
      sc.Parameters.Add(new SqlParameter("@empId",SqlDbType.Int)).Value = Int32.Parse(anID.ToString());
      SqlDataReader sdr = null;

      try {
        conn.Open();
        sdr = sc.ExecuteReader();

        // This is not a while loop. It only loops once.
        if (sdr != null && sdr.Read()) {
          // The IEnumerable contains DataRowView objects.
          this.firstName        = sdr["FirstName"].ToString();
          this.lastName         = sdr["LastName"].ToString();
        }
        else {
          throw new NorthwindDataException("Data not loaded for employee id.");
        }
      }
      finally {
        try {
          if (sdr != null) sdr.Close();
          conn.Close();
        }
        catch (SqlException) {
          // Log an event in the Application Event Log.
          throw;
        }
      }
    }

    private object ID;
    public object EmpID {
      get { return ID; }
    }

    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 bool Delete () {
      if (ID.Equals(DBNull.Value)) {
        // The Employee object is not persisted.
        return true;
      }
      else {
        // The Employee object is persisted.
        // Use the SqlDataSource control as a convenient wrapper for
        // the ADO.NET code needed to delete a record from the database.
        ConnectionStringSettings cts = ConfigurationManager.ConnectionStrings["NorthwindConnection"];
        SqlDataSource sds = new SqlDataSource();

        try {
          sds.ConnectionString = cts.ConnectionString;
          sds.DeleteParameters.Add(new Parameter("empID", TypeCode.Int32, this.ID.ToString()));
          sds.DeleteCommand = "DELETE FROM [Order Details] " + 
              "WHERE OrderID IN (SELECT OrderID FROM Orders WHERE EmployeeID=@empID)";
          sds.Delete();
          sds.DeleteCommand = "DELETE FROM Orders WHERE EmployeeID=@empID";
          sds.Delete();
          sds.DeleteCommand = "DELETE FROM EmployeeTerritories WHERE EmployeeID=@empID";
          sds.Delete();
          sds.DeleteCommand = "DELETE FROM Employees WHERE EmployeeID=@empID";
          sds.Delete();
          return true;
        }
        finally {
          // Clean up resources.
          sds.Dispose();
        }
      }
    }
  }

  public class NorthwindDataException: Exception {
    public NorthwindDataException(string msg) : base (msg) { }
  }
}
Imports System.Collections
Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.UI
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

   ' Return a collection of NorthwindEmployee objects.
   Public Shared Function GetAllEmployees() As ICollection
      Dim al As New ArrayList()

      ' Use the SqlDataSource class to wrap the
      ' ADO.NET code required to query the database.
      Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection")
      Dim sds As New SqlDataSource(cts.ConnectionString, _
                                  "SELECT EmployeeID FROM Employees")
      Try
         Dim IDs As IEnumerable = sds.Select(DataSourceSelectArguments.Empty)

         ' Iterate through the Enumeration and create a
         ' NorthwindEmployee object for each ID.
         Dim enumerator As IEnumerator = IDs.GetEnumerator()
         While enumerator.MoveNext()
            ' The IEnumerable contains DataRowView objects.
            Dim row As DataRowView = CType(enumerator.Current,DataRowView)
            Dim id As String = row("EmployeeID").ToString()
            Dim nwe As New NorthwindEmployee(id)
            ' Add the NorthwindEmployee object to the collection.
            al.Add(nwe)
         End While
      Finally
         ' If anything strange happens, clean up.
         sds.Dispose()
      End Try

      Return al
   End Function 'GetAllEmployees


   Public Shared Function GetEmployee(anID As Object) As NorthwindEmployee
      Return New NorthwindEmployee(anID)
   End Function 'GetEmployee


   Public Shared Sub DeleteEmployee(ne As NorthwindEmployee)
      Dim retval As Boolean = ne.Delete()
      If Not retval Then
         Throw New NorthwindDataException("Employee delete failed.")
      End If ' Delete the object in memory.
      ne = Nothing
   End Sub


   Public Shared Sub DeleteEmployeeByID(anID As Integer)
      Dim tempEmp As New NorthwindEmployee(anID)
      DeleteEmployee(tempEmp)
   End Sub

End Class

Public Class NorthwindEmployee

   Public Sub New()
      ID = DBNull.Value
      aLastName = ""
      aFirstName = ""
   End Sub


   Public Sub New(anID As Object)
      Me.ID = anID
      Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection")
      Dim conn As New SqlConnection(cts.ConnectionString)
      Dim sc As New SqlCommand(" SELECT FirstName,LastName " & _
                               " FROM Employees " & _
                               " WHERE EmployeeID = @empId", conn)
      ' Add the employee ID parameter and set its value.
      sc.Parameters.Add(New SqlParameter("@empId", SqlDbType.Int)).Value = Int32.Parse(anID.ToString())
      Dim sdr As SqlDataReader = Nothing

      Try
         conn.Open()
         sdr = sc.ExecuteReader()

         ' This is not a while loop. It only loops once.
         If Not (sdr Is Nothing) AndAlso sdr.Read() Then
            ' The IEnumerable contains DataRowView objects.
            Me.aFirstName = sdr("FirstName").ToString()
            Me.aLastName = sdr("LastName").ToString()
         Else
            Throw New NorthwindDataException("Data not loaded for employee id.")
         End If
      Finally
         Try
            If Not (sdr Is Nothing) Then
               sdr.Close()
            End If
            conn.Close()
         Catch se As SqlException
            ' Log an event in the Application Event Log.
            Throw
         End Try
      End Try
   End Sub

   Private ID As Object
   Public ReadOnly Property EmpID() As Object
      Get
         Return ID
      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 Function Delete() As Boolean
      If ID.Equals(DBNull.Value) Then
         ' The Employee object is not persisted.
         Return True
      Else
         ' The Employee object is persisted.
         ' Use the SqlDataSource control as a convenient wrapper for
         ' the ADO.NET code needed to delete a record from the database.
         Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection")
         Dim sds As New SqlDataSource()
         Try
            sds.ConnectionString = cts.ConnectionString
            sds.DeleteParameters.Add(New Parameter("empID", TypeCode.Int32, Me.ID.ToString()))
            sds.DeleteCommand = "DELETE FROM [Order Details] " & _
                "WHERE OrderID IN (SELECT OrderID FROM Orders WHERE EmployeeID=@empID)"
            sds.Delete()
            sds.DeleteCommand = "DELETE FROM Orders WHERE EmployeeID=@empID"
            sds.Delete()
            sds.DeleteCommand = "DELETE FROM EmployeeTerritories WHERE EmployeeID=@empID"
            sds.Delete()
            sds.DeleteCommand = "DELETE FROM Employees WHERE EmployeeID=@empID"
            sds.Delete()
            Return True
         Finally
            ' Clean up resources.
            sds.Dispose()
         End Try
      End If
   End Function 'Delete
End Class

Public Class NorthwindDataException
   Inherits Exception

   Public Sub New(msg As String)
      MyBase.New(msg)
   End Sub

End Class
End Namespace

注解

处理事件以检查返回值或输出参数的值, 或确定在Delete操作完成后是否引发了异常。 DeletedHandle the Deleted event to examine the values of a return value or output parameters, or to determine whether an exception was thrown after a Delete operation has completed. 可从与事件关联的ObjectDataSourceStatusEventArgs对象中获取返回值、输出参数和异常处理属性。The return value, output parameters, and exception handling properties are available from the ObjectDataSourceStatusEventArgs object that is associated with the event.

可以使用ObjectDataSourceStatusEventArgs对象的AffectedRows属性来返回从Delete方法中删除的行数。You can use the AffectedRows property of the ObjectDataSourceStatusEventArgs object to return the number of rows that were deleted from the Delete method. 为此, 请设置AffectedRows属性。To do this, set the AffectedRows property. 如果从DeleteMethod属性指定的方法返回删除的行数, 则可以ReturnValueObjectDataSourceStatusEventArgs对象的属性中获取值。If you return the number of deleted rows from the method that is specified by the DeleteMethod property, the value is available from the ReturnValue property of the ObjectDataSourceStatusEventArgs object.

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.

适用于

另请参阅