ObjectDataSource.Update Metodo
Definizione
Importante
Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.
Esegue un'operazione di aggiornamento chiamando il metodo identificato dalla proprietà UpdateMethod e dai parametri contenuti nell'insieme UpdateParameters.
public:
int Update();public int Update ();member this.Update : unit -> intPublic Function Update () As IntegerRestituisce
Valore che rappresenta il numero di righe aggiornate nell'archivio dati sottostante.
Esempio
In questa sezione sono riportati due esempi di codice. Il primo esempio di codice illustra come usare un DropDownList controllo, TextBox controlli e diversi ObjectDataSource oggetti per aggiornare i dati. Il secondo esempio di codice mostra la EmployeeLogic classe usata nel primo esempio di codice.
Nell'esempio di codice seguente viene illustrato come usare un DropDownList controllo, TextBox controlli e diversi ObjectDataSource controlli per aggiornare i dati. DropDownList Visualizza il nome di un dipendente Northwind, mentre i TextBox controlli vengono usati per immettere e aggiornare le informazioni sull'indirizzo. Poiché l'insieme UpdateParameters contiene un ControlParameter oggetto associato al valore selezionato di DropDownList, il pulsante che genera l'operazione Update viene abilitato solo dopo l'selezione di un dipendente.
Importante
L'esempio include una casella di testo che accetta l'input dell'utente e rappresenta quindi una potenziale minaccia alla sicurezza. Per impostazione predefinita, le pagine Web ASP.NET verificano che l'input dell'utente non includa script o elementi HTML. Per altre informazioni, vedere Cenni preliminari sugli attacchi tramite script.
<%@ 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>
Nell'esempio di codice seguente viene illustrata la EmployeeLogic classe usata nell'esempio 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 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
Commenti
Si presuppone che l'oggetto business aggiorni un record alla volta, anziché in un batch.
Prima di eseguire l'operazione Update , viene chiamato il OnUpdating metodo per generare l'evento Updating . È possibile gestire l'evento Updating per esaminare i valori dei parametri e per eseguire qualsiasi pre-elaborazione prima di un'operazione Update . Per eseguire un'operazione di aggiornamento, l'oggetto ObjectDataSourceView utilizza la reflection per creare un'istanza dell'oggetto identificato dalla TypeName proprietà . Chiama quindi il metodo identificato dalla UpdateMethod proprietà , utilizzando le proprietà associate UpdateParameters . Al termine dell'operazione Update , viene chiamato il OnUpdated metodo per generare l'evento Updated . È possibile gestire l'evento Updated per esaminare tutti i valori restituiti, i parametri di output e le eccezioni e per eseguire qualsiasi post-elaborazione.
Il Update metodo delega al Update metodo dell'oggetto ObjectDataSourceView associato al ObjectDataSource controllo .
Per altre informazioni sull'unione dei parametri, sulla durata degli oggetti e sulla risoluzione dei metodi, vedere UpdateMethod.
Importante
È necessario convalidare qualsiasi valore di parametro ricevuto dal client. Il runtime sostituisce semplicemente il valore del parametro nella UpdateMethod proprietà .
controlli Data-Bound
Quando il ObjectDataSource controllo è associato a un controllo associato a dati, ad esempio il GridView controllo , non è necessario chiamare il metodo dal codice della Update tabella. Il Update metodo viene richiamato direttamente dal controllo associato a dati.
Si applica a
Vedi anche
Collabora con noi su GitHub
L'origine di questo contenuto è disponibile in GitHub, in cui è anche possibile creare ed esaminare i problemi e le richieste pull. Per ulteriori informazioni, vedere la guida per i collaboratori.
