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ObjectDataSource.DeleteParameters Proprietà

Definizione

Ottiene l'insieme di parametri contenente i parametri utilizzati dal metodo DeleteMethod.

public:
 property System::Web::UI::WebControls::ParameterCollection ^ DeleteParameters { System::Web::UI::WebControls::ParameterCollection ^ get(); };
[System.Web.UI.PersistenceMode(System.Web.UI.PersistenceMode.InnerProperty)]
public System.Web.UI.WebControls.ParameterCollection DeleteParameters { get; }
[<System.Web.UI.PersistenceMode(System.Web.UI.PersistenceMode.InnerProperty)>]
member this.DeleteParameters : System.Web.UI.WebControls.ParameterCollection
Public ReadOnly Property DeleteParameters As ParameterCollection

Valore della proprietà

Oggetto ParameterCollection contenente i parametri utilizzati dal metodo DeleteMethod.

Attributi

Esempio

In questa sezione sono riportati due esempi di codice. Il primo esempio di codice illustra come usare un oggetto con un ObjectDataSource oggetto business e un GridView controllo per eliminare i dati. Il secondo esempio di codice mostra la EmployeeLogic classe usata nel primo esempio di codice.

Nell'esempio ObjectDataSource di codice seguente viene illustrato come usare la DeleteParameters proprietà del controllo con un oggetto business e un GridView controllo per eliminare i dati. Inizialmente, il controllo visualizza un set di tutti i dipendenti, usando il GridView metodo specificato dalla SelectMethod proprietà per recuperare i dati dall'oggetto EmployeeLogic . Poiché la AutoGenerateDeleteButton proprietà è impostata su true, il GridView controllo visualizza automaticamente un pulsante Delete .

Se si fa clic sul pulsante Elimina , l'evento Deleting viene chiamato con due parametri. Un parametro, EmpID, proviene dal DataGrid controllo e si basa sulla DataKeyNames proprietà . L'altro parametro proviene dalla proprietà dichiarativa DeleteParameters . La EmployeeLogic classe esegue l'overload del DeleteEmployee metodo. Un overload accetta un parametro e l'altro accetta un NorthwindEmployeeInt32 parametro denominato anID. Nell'evento Deleting , le voci nella InputParameters proprietà vengono regolate per includere un solo parametro denominato anID con il valore da original_EmpID. Quando esiste il gestore eventi, viene chiamato il metodo corrispondente DeleteEmployee .

Nell'esempio di codice seguente viene illustrata la pagina Web che visualizza il controllo e gestisce l'evento DataGridDeleting .

<%@ 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)
{
  IDictionary paramsFromPage = e.InputParameters;

  paramsFromPage.Remove("anID");
  paramsFromPage.Add("anID", (int)paramsFromPage["EmpID"]);
  paramsFromPage.Remove("EmpID");
    
}
</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"
          DataKeyNames="EmpID">
        </asp:gridview>

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

    </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">
Private Sub NorthwindEmployeeDeleting(source As Object, e As ObjectDataSourceMethodEventArgs)

  Dim paramsFromPage As IDictionary = e.InputParameters

  paramsFromPage.Remove("anID")
  paramsFromPage.Add("anID", CInt(paramsFromPage("EmpID")))
  paramsFromPage.Remove("EmpID")

End Sub ' NorthwindEmployeeDeleting
</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"
          DataKeyNames="EmpID">
        </asp:gridview>

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

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

Nell'esempio di codice seguente viene illustrata la classe usata nell'esempio EmployeeLogic di codice precedente.

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;
          int id = (int) row["EmployeeID"];
          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(int 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 DeleteEmployee(int anID) {
        NorthwindEmployee tempEmp = new NorthwindEmployee(anID);
        DeleteEmployee(tempEmp);
    }
  }
  public class NorthwindEmployee {

    public NorthwindEmployee (int 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.DeleteCommand = "DELETE FROM Employees WHERE EmployeeID=@empID;";
          sds.DeleteParameters.Add(new Parameter("empID",TypeCode.Int32,this.ID.ToString()));

          /* To make this sample fully functional, uncomment these lines
          int retval = sds.Delete();
          if (retval == 1) { return true; }
          return false; */

          return true;
        }
        finally {
          sds.Dispose();
        }
      }
    }
  }
  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 you 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(CInt(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 Integer) 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 DeleteEmployee(anID As Integer)
      Dim tempEmp As New NorthwindEmployee(anID)
      DeleteEmployee(tempEmp)
   End Sub

   ' And so on...

End Class

Public Class NorthwindEmployee

   Public Sub New(anID As Integer)
      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.firstName = sdr("FirstName").ToString()
            Me.lastName = 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.DeleteCommand = "DELETE FROM Employees WHERE EmployeeID=@empID;"
                    Dim param As New Parameter("empID", TypeCode.Int32, CStr(Me.ID))
            sds.DeleteParameters.Add(param)

            ' To make this sample fully functional, uncomment these lines
'          int retval = sds.Delete();
'          if (retval == 1) { return true; }
'          return false;

            Return True
         Finally
            sds.Dispose()
         End Try
      End If
   End Function 'Delete

End Class

Friend Class NorthwindDataException
   Inherits Exception

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

End Namespace

Commenti

I nomi e i tipi dei parametri contenuti nell'insieme DeleteParameters devono corrispondere ai nomi e ai tipi dei parametri nella firma del DeleteMethod metodo. I nomi dei parametri sono interessati dalla OldValuesParameterFormatString proprietà e sono distinzione tra maiuscole e minuscole. I parametri della raccolta dipendono dai dati inclusi nel controllo associato a dati, dai parametri specificati in modo dichiarativo e dai parametri aggiunti a livello di codice. Per altre informazioni, vedere "Unione dei parametri" in Delete e Uso dei parametri con il controllo ObjectDataSource.

La DeleteParameters proprietà recupera la DeleteParameters proprietà contenuta dall'oggetto ObjectDataSourceView associato al ObjectDataSource controllo.

Per altre informazioni sull'unione dei parametri, sulla durata dell'oggetto e sulla risoluzione dei metodi, vedere DeleteMethod.

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