ObjectDataSource.Update 方法

定义

通过调用 UpdateMethod 属性标识的方法和 UpdateParameters 集合中的所有参数,执行更新操作。

public:
 int Update();
public int Update ();
member this.Update : unit -> int
Public Function Update () As Integer

返回

一个值,表示基础数据存储中更新的行数。

示例

本部分包含两个代码示例。 第一个代码示例演示如何使用控件 DropDownListTextBox 控件和多个 ObjectDataSource 对象来更新数据。 第二个代码示例演示在第 EmployeeLogic 一个代码示例中使用的类。

下面的代码示例演示如何使用控件 DropDownListTextBox 控件和多个 ObjectDataSource 控件来更新数据。 显示 DropDownList Northwind 员工的姓名,而 TextBox 控件用于输入和更新地址信息。 UpdateParameters由于集合包含绑定到 ControlParameter 的选定值DropDownList的对象,因此,仅当选择员工后,才会启用引发操作的Update按钮。

重要

此示例具有一个接受用户输入的文本框,这是一个潜在的安全威胁。 默认情况下,ASP.NET 网页验证用户输入是否不包含脚本或 HTML 元素。 有关详细信息,请参阅脚本侵入概述

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

// Add parameters and initialize the user interface
// only if an employee is selected.
private void Page_Load(object sender, EventArgs e)
{
  // Be sure the text boxes are initialized with
  // data from the currently selected employee.
  NorthwindEmployee selectedEmployee = EmployeeLogic.GetEmployee(DropDownList1.SelectedValue);
  if (selectedEmployee != null) {
    AddressBox.Text    = selectedEmployee.Address;
    CityBox.Text       = selectedEmployee.City;
    PostalCodeBox.Text = selectedEmployee.PostalCode;

    Button1.Enabled = true;
  }
  else {
    Button1.Enabled = false;
  }
}

// Press the button to update.
private void Btn_UpdateEmployee (object sender, CommandEventArgs e) {
  ObjectDataSource2.Update();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <!-- The DropDownList is bound to the first ObjectDataSource. -->
        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          typename="Samples.AspNet.CS.EmployeeLogic" />

        <p><asp:dropdownlist
          id="DropDownList1"
          runat="server"
          datasourceid="ObjectDataSource1"
          datatextfield="FullName"
          datavaluefield="EmpID"
          autopostback="True" /></p>

        <!-- The second ObjectDataSource performs the Update. This
             preserves the state of the DropDownList, which otherwise
             would rebind when the DataSourceChanged event is
             raised as a result of an Update operation. -->

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

        <asp:objectdatasource
          id="ObjectDataSource2"
          runat="server"
          updatemethod="UpdateEmployeeWrapper"
          typename="Samples.AspNet.CS.EmployeeLogic">
          <updateparameters>
            <asp:controlparameter name="anID" controlid="DropDownList1" propertyname="SelectedValue" />
            <asp:formparameter name="anAddress" formfield="AddressBox" />
            <asp:formparameter name="aCity" formfield="CityBox" />
            <asp:formparameter name="aPostalCode" formfield="PostalCodeBox" />
          </updateparameters>
        </asp:objectdatasource>

        <p><asp:textbox
          id="AddressBox"
          runat="server" /></p>

        <p><asp:textbox
          id="CityBox"
          runat="server" /></p>

        <p><asp:textbox
          id="PostalCodeBox"
          runat="server" /></p>

        <asp:button
          id="Button1"
          runat="server"
          text="Update Employee"
          oncommand="Btn_UpdateEmployee" />

    </form>
  </body>
</html>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB" Assembly="Samples.AspNet.VB" %>
<%@ Page language="vb" %>
<%@ Import namespace="Samples.AspNet.VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

' Add parameters and initialize the user interface
' only if an employee is selected.
Private Sub Page_Load(sender As Object, e As EventArgs)

  ' Be sure the text boxes are initialized with
  ' data from the currently selected employee.
  Dim selectedEmployee As NorthwindEmployee
  selectedEmployee = EmployeeLogic.GetEmployee(DropDownList1.SelectedValue)

  If Not selectedEmployee Is Nothing Then
    AddressBox.Text    = selectedEmployee.Address
    CityBox.Text       = selectedEmployee.City
    PostalCodeBox.Text = selectedEmployee.PostalCode

    Button1.Enabled = True
  Else
    Button1.Enabled = False
  End If
End Sub ' Page_Load

' Press the button to update.
Private Sub Btn_UpdateEmployee (sender As Object, e As CommandEventArgs )
  ObjectDataSource2.Update()
End Sub ' Btn_UpdateEmployee

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

        <!-- The DropDownList is bound to the first ObjectDataSource. -->
        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          typename="Samples.AspNet.VB.EmployeeLogic" />

        <p><asp:dropdownlist
          id="DropDownList1"
          runat="server"
          datasourceid="ObjectDataSource1"
          datatextfield="FullName"
          datavaluefield="EmpID"
          autopostback="True" /></p>

        <!-- The second ObjectDataSource performs the Update. This
             preserves the state of the DropDownList, which otherwise
             would rebind when the DataSourceChanged event is
             raised as a result of an Update operation. -->

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

        <asp:objectdatasource
          id="ObjectDataSource2"
          runat="server"
          updatemethod="UpdateEmployeeWrapper"
          typename="Samples.AspNet.VB.EmployeeLogic">
          <updateparameters>
            <asp:controlparameter name="anID" controlid="DropDownList1" propertyname="SelectedValue" />
            <asp:formparameter name="anAddress" formfield="AddressBox" />
            <asp:formparameter name="aCity" formfield="CityBox" />
            <asp:formparameter name="aPostalCode" formfield="PostalCodeBox" />
          </updateparameters>
        </asp:objectdatasource>

        <p><asp:textbox
          id="AddressBox"
          runat="server" /></p>

        <p><asp:textbox
          id="CityBox"
          runat="server" /></p>

        <p><asp:textbox
          id="PostalCodeBox"
          runat="server" /></p>

        <asp:button
          id="Button1"
          runat="server"
          text="Update Employee"
          oncommand="Btn_UpdateEmployee" />

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

下面的代码示例演示在 EmployeeLogic 前面的代码示例中使用的 类。

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 one 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) {
      ArrayList al = GetAllEmployees() as ArrayList;
      IEnumerator enumerator = al.GetEnumerator();
      while (enumerator.MoveNext()) {
        // The IEnumerable contains initialized NorthwindEmployee objects.
        NorthwindEmployee ne = enumerator.Current as NorthwindEmployee;
        if (ne.EmpID.Equals(anID.ToString())) {
          return ne;
        }
      }
      return null;
    }
    public static void UpdateEmployee(NorthwindEmployee ne) {
      bool retval = ne.Update();
      if (! retval) { throw new NorthwindDataException("Employee update failed."); }
    }

    // This method is added as a conveniece wrapper on the original
    // implementation.
    public static void UpdateEmployeeWrapper(string anID,
                                             string anAddress,
                                             string aCity,
                                             string aPostalCode) {
      NorthwindEmployee ne = new NorthwindEmployee(anID);
      ne.Address = anAddress;
      ne.City = aCity;
      ne.PostalCode = aPostalCode;
      UpdateEmployee(ne);
    }

    // And so on...
  }

  public class NorthwindEmployee {

    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,Address,City,PostalCode " +
                       " 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();
          this.address         = sdr["Address"].ToString();
          this.city            = sdr["City"].ToString();
          this.postalCode      = sdr["PostalCode"].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 {
      set { lastName = value; }
    }

    private string firstName;
    public string FirstName {
      set { firstName = value;  }
    }

    public string FullName {
      get { return firstName + " " + lastName; }
    }

    private string address;
    public string Address {
      get { return address; }
      set { address = value;  }
    }

    private string city;
    public string City {
      get { return city; }
      set { city = value;  }
    }

    private string postalCode;
    public string PostalCode {
      get { return postalCode; }
      set { postalCode = value;  }
    }

    public bool Update () {

      // Implement Update logic.

      return true;
    }
  }

  internal 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 one can perform on a NorthwindEmployee object.
'
Public Class EmployeeLogic

   ' Returns 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
      Dim al As ArrayList = CType(GetAllEmployees(), ArrayList)
      Dim enumerator As IEnumerator = al.GetEnumerator()
      While enumerator.MoveNext()
         ' The IEnumerable contains initialized NorthwindEmployee objects.
         Dim ne As NorthwindEmployee = CType(enumerator.Current,NorthwindEmployee)
         If ne.EmpID.Equals(anID.ToString()) Then
            Return ne
         End If
      End While
      Return Nothing
   End Function 'GetEmployee

   Public Shared Sub UpdateEmployee(ne As NorthwindEmployee)
      Dim retval As Boolean = ne.Update()
      If Not retval Then
         Throw New NorthwindDataException("Employee update failed.")
      End If
   End Sub

   ' This method is added as a conveniece wrapper on the original
   ' implementation.
   Public Shared Sub UpdateEmployeeWrapper(anID As String, _
                                           anAddress As String, _
                                           aCity As String, _
                                           aPostalCode As String)
      Dim ne As New NorthwindEmployee(anID)
      ne.Address = anAddress
      ne.City = aCity
      ne.PostalCode = aPostalCode
      UpdateEmployee(ne)
   End Sub
   ' And so on...

End Class

Public Class NorthwindEmployee

   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,Address,City,PostalCode " & _
                               " 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()
            Me.aAddress = sdr("Address").ToString()
            Me.aCity = sdr("City").ToString()
            Me.aPostalCode = sdr("PostalCode").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 WriteOnly Property LastName() As String
      Set
         aLastName = value
      End Set
   End Property

   Private aFirstName As String
   Public WriteOnly Property FirstName() As String
      Set
         aFirstName = value
      End Set
   End Property

   Public ReadOnly Property FullName() As String
      Get
         Return aFirstName & " " & aLastName
      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

   Private aCity As String
   Public Property City() As String
      Get
         Return aCity
      End Get
      Set
         aCity = value
      End Set
   End Property

   Private aPostalCode As String
   Public Property PostalCode() As String
      Get
         Return aPostalCode
      End Get
      Set
         aPostalCode = value
      End Set
   End Property

   Public Function Update() As Boolean

      ' Implement Update logic.
      Return True

   End Function 'Update

End Class

Friend Class NorthwindDataException
   Inherits Exception

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

End Class
End Namespace

注解

假定业务对象一次更新一条记录,而不是批量更新数据。

在执行 Update 操作之前, OnUpdating 将调用 方法来引发 Updating 事件。 可以处理 事件以 Updating 检查参数的值,并在操作之前 Update 执行任何预处理。 为了执行更新操作, ObjectDataSourceView 对象使用反射来创建 由 TypeName 属性标识的 对象的实例。 然后,它使用任何关联的UpdateParameters属性调用 由 UpdateMethod 属性标识的方法。 操作 Update 完成后, OnUpdated 将调用 方法来引发 Updated 事件。 可以处理 Updated 事件以检查任何返回值、输出参数和异常,并执行任何后期处理。

方法Update委托给UpdateObjectDataSourceView与 控件关联的 的 方法ObjectDataSource

有关参数合并、对象生存期和方法解析的详细信息,请参阅 UpdateMethod

重要

应验证从客户端接收的任何参数值。 运行时只是将参数值 UpdateMethod 替换为 属性。

数据绑定控件

当控件 ObjectDataSource 与数据绑定控件(如 GridView 控件)关联时,无需从页面代码调用 Update 方法。 方法 Update 由数据绑定控件直接调用。

适用于

另请参阅