DetailsViewUpdateEventHandler Delegát
Definice
Důležité
Některé informace platí pro předběžně vydaný produkt, který se může zásadně změnit, než ho výrobce nebo autor vydá. Microsoft neposkytuje žádné záruky, výslovné ani předpokládané, týkající se zde uváděných informací.
Představuje metodu, která zpracovává ItemUpdating událost DetailsView ovládacího prvku.
public delegate void DetailsViewUpdateEventHandler(System::Object ^ sender, DetailsViewUpdateEventArgs ^ e);public delegate void DetailsViewUpdateEventHandler(object sender, DetailsViewUpdateEventArgs e);type DetailsViewUpdateEventHandler = delegate of obj * DetailsViewUpdateEventArgs -> unitPublic Delegate Sub DetailsViewUpdateEventHandler(sender As Object, e As DetailsViewUpdateEventArgs)Parametry
- sender
- Object
Zdroj události
A DetailsViewUpdateEventArgs obsahující data události.
Příklady
Následující příklad kódu ukazuje, jak programově přidat DetailsViewUpdateEventHandler delegáta na ItemUpdating událost DetailsView ovládacího prvku.
<%@ 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">
void Page_Load(Object sender, EventArgs e)
{
// Create a new DetailsView object.
DetailsView customerDetailsView = new DetailsView();
// Set the DetailsView object's properties.
customerDetailsView.ID = "CustomerDetailsView";
customerDetailsView.DataSourceID = "DetailsViewSource";
customerDetailsView.AutoGenerateRows = true;
customerDetailsView.AutoGenerateEditButton = true;
customerDetailsView.AllowPaging = true;
customerDetailsView.DataKeyNames = new String[1] { "CustomerID" };
customerDetailsView.PagerSettings.Position = PagerPosition.Bottom;
// Programmatically register the event-handling methods
// for the DetailsView control.
customerDetailsView.ItemUpdating
+= new DetailsViewUpdateEventHandler(
this.CustomerDetailsView_ItemUpdating);
customerDetailsView.ModeChanging
+= new DetailsViewModeEventHandler(
this.CustomerDetailsView_ModeChanging);
// Add the DetailsView object to the Controls collection
// of the PlaceHolder control.
DetailsViewPlaceHolder.Controls.Add(customerDetailsView);
}
void CustomerDetailsView_ItemUpdating(Object sender,
DetailsViewUpdateEventArgs e)
{
// Validate the field values entered by the user. This
// example determines whether the user left any fields
// empty. Use the NewValues property to access the new
// values entered by the user.
ArrayList emptyFieldList =
ValidateFields((IOrderedDictionary)e.NewValues);
if (emptyFieldList.Count > 0)
{
// The user left some fields empty. Display an error message.
// Use the Keys property to retrieve the key field value.
String keyValue = e.Keys["CustomerID"].ToString();
MessageLabel.Text =
"You must enter a value for all fields of record " +
keyValue + ".<br/>The following fields are missing:<br/><br/>";
// Display the missing fields.
foreach (String value in emptyFieldList)
{
// Use the OldValues property access the original value
// of a field.
MessageLabel.Text += value + " - Original Value = " +
e.OldValues[value].ToString() + "<br />";
}
// Cancel the update operation.
e.Cancel = true;
}
else
{
// The field values passed validation. Clear the
// error message label.
MessageLabel.Text = "";
}
}
ArrayList ValidateFields(IOrderedDictionary list)
{
// Create an ArrayList object to store the
// names of any empty fields.
ArrayList emptyFieldList = new ArrayList();
// Iterate though the field values entered by
// the user and check for an empty field. Empty
// fields contain a null value.
foreach (DictionaryEntry entry in list)
{
if (entry.Value == null)
{
// Add the field name to the ArrayList object.
emptyFieldList.Add(entry.Key.ToString());
}
}
return emptyFieldList;
}
void CustomerDetailsView_ModeChanging(Object sender,
DetailsViewModeEventArgs e)
{
if (e.CancelingEdit)
{
// The user canceled the update operation.
// Clear the error message label.
MessageLabel.Text = "";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DetailsViewUpdateEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DetailsViewUpdateEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated DetailsView control. -->
<asp:placeholder id="DetailsViewPlaceHolder"
runat="server"/>
<br/><br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Northwind sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the web.config file. -->
<asp:sqldatasource id="DetailsViewSource"
selectcommand="Select [CustomerID], [CompanyName], [Address],
[City], [PostalCode], [Country] From [Customers]"
updatecommand="Update [Customers] Set
[CompanyName]=@CompanyName, [Address]=@Address,
[City]=@City, [PostalCode]=@PostalCode,
[Country]=@Country
Where [CustomerID]=@CustomerID"
connectionstring=
"<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
<%@ 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">
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
' Create a new DetailsView object.
Dim customerDetailsView As New DetailsView()
' Set the DetailsView object's properties.
customerDetailsView.ID = "CustomerDetailsView"
customerDetailsView.DataSourceID = "DetailsViewSource"
customerDetailsView.AutoGenerateRows = True
customerDetailsView.AutoGenerateEditButton = True
customerDetailsView.AllowPaging = True
customerDetailsView.PagerSettings.Position = PagerPosition.Bottom
Dim keyArray() As String = {"CustomerID"}
customerDetailsView.DataKeyNames = keyArray
' Programmatically register the event-handling methods
' for the DetailsView control.
AddHandler customerDetailsView.ItemUpdating, _
AddressOf CustomerDetailsView_ItemUpdating
AddHandler customerDetailsView.ModeChanging, _
AddressOf CustomerDetailsView_ModeChanging
' Add the DetailsView object to the Controls collection
' of the PlaceHolder control.
DetailsViewPlaceHolder.Controls.Add(customerDetailsView)
End Sub
Sub CustomerDetailsView_ItemUpdating(ByVal sender As Object, _
ByVal e As DetailsViewUpdateEventArgs)
' Validate the field values entered by the user. This
' example determines whether the user left any fields
' empty. Use the NewValues property to access the new
' values entered by the user.
Dim emptyFieldList As ArrayList = _
ValidateFields(CType(e.NewValues, IOrderedDictionary))
If emptyFieldList.Count > 0 Then
' The user left some fields empty. Display an error message.
' Use the Keys property to retrieve the key field value.
Dim keyValue As String = e.Keys("CustomerID").ToString()
MessageLabel.Text = _
"You must enter a value for all fields of record " & _
keyValue & ".<br/>The following fields are missing:<br/><br/>"
' Display the missing fields.
Dim value As String
For Each value In emptyFieldList
' Use the OldValues property access the original value
' of a field.
MessageLabel.Text &= value & " - Original Value = " & _
e.OldValues(value).ToString() & "<br />"
Next
' Cancel the update operation.
e.Cancel = True
Else
' The field values passed validation. Clear the
' error message label.
MessageLabel.Text = ""
End If
End Sub
Function ValidateFields(ByVal list As IOrderedDictionary) _
As ArrayList
' Create an ArrayList object to store the
' names of any empty fields.
Dim emptyFieldList As New ArrayList()
' Iterate though the field values entered by
' the user and check for an empty field. Empty
' fields contain a null value.
Dim entry As DictionaryEntry
For Each entry In list
If entry.Value Is Nothing Then
' Add the field name to the ArrayList object.
emptyFieldList.Add(entry.Key.ToString())
End If
Next
Return emptyFieldList
End Function
Sub CustomerDetailsView_ModeChanging(ByVal sender As Object, ByVal e As DetailsViewModeEventArgs)
If e.CancelingEdit Then
' The user canceled the update operation.
' Clear the error message label.
MessageLabel.Text = ""
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DetailsViewUpdateEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DetailsViewUpdateEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated DetailsView control. -->
<asp:placeholder id="DetailsViewPlaceHolder"
runat="server"/>
<br/><br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Northwind sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the web.config file. -->
<asp:sqldatasource id="DetailsViewSource"
selectcommand="Select [CustomerID], [CompanyName], [Address],
[City], [PostalCode], [Country] From [Customers]"
updatecommand="Update [Customers] Set
[CompanyName]=@CompanyName, [Address]=@Address,
[City]=@City, [PostalCode]=@PostalCode,
[Country]=@Country Where [CustomerID]=@CustomerID"
connectionstring=
"<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
s </form>
</body>
</html>
Následující příklad kódu ukazuje, jak deklarativní přidat DetailsViewUpdateEventHandler delegáta na ItemUpdating událost DetailsView ovládacího prvku.
<%@ 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">
void CustomerDetailsView_ItemUpdating(Object sender,
DetailsViewUpdateEventArgs e)
{
// Validate the field values entered by the user. This
// example determines whether the user left any fields
// empty. Use the NewValues property to access the new
// values entered by the user.
ArrayList emptyFieldList =
ValidateFields((IOrderedDictionary)e.NewValues);
if (emptyFieldList.Count > 0)
{
// The user left some fields empty. Display an error message.
// Use the Keys property to retrieve the key field value.
String keyValue = e.Keys["CustomerID"].ToString();
MessageLabel.Text =
"You must enter a value for all fields of record " +
keyValue + ".<br/>The following fields are missing:<br/><br/>";
// Display the missing fields.
foreach (String value in emptyFieldList)
{
// Use the OldValues property access the original value
// of a field.
MessageLabel.Text += value + " - Original Value = " +
e.OldValues[value].ToString() + "<br />";
}
// Cancel the update operation.
e.Cancel = true;
}
else
{
// The field values passed validation. Clear the
// error message label.
MessageLabel.Text = "";
}
}
ArrayList ValidateFields(IOrderedDictionary list)
{
// Create an ArrayList object to store the
// names of any empty fields.
ArrayList emptyFieldList = new ArrayList();
// Iterate though the field values entered by
// the user and check for an empty field. Empty
// fields contain a null value.
foreach (DictionaryEntry entry in list)
{
if (entry.Value == null)
{
// Add the field name to the ArrayList object.
emptyFieldList.Add(entry.Key.ToString());
}
}
return emptyFieldList;
}
void CustomerDetailsView_ModeChanging(Object sender,
DetailsViewModeEventArgs e)
{
if (e.CancelingEdit)
{
// The user canceled the update operation.
// Clear the error message label.
MessageLabel.Text = "";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DetailsViewUpdateEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DetailsViewUpdateEventHandler Example</h3>
<asp:detailsview id="CustomerDetailsView"
datasourceid="DetailsViewSource"
autogeneraterows="true"
autogenerateeditbutton="true"
allowpaging="true"
datakeynames="CustomerID"
onitemupdating="CustomerDetailsView_ItemUpdating"
onmodechanging="CustomerDetailsView_ModeChanging"
runat="server">
<pagersettings position="Bottom"/>
</asp:detailsview>
<br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Northwind sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the web.config file. -->
<asp:sqldatasource id="DetailsViewSource"
selectcommand="Select [CustomerID], [CompanyName], [Address],
[City], [PostalCode], [Country] From [Customers]"
updatecommand="Update [Customers] Set
[CompanyName]=@CompanyName, [Address]=@Address,
[City]=@City, [PostalCode]=@PostalCode,
[Country]=@Country
Where [CustomerID]=@CustomerID"
connectionstring=
"<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
<%@ Page language="VB" autoeventwireup="false" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub CustomerDetailsView_ItemUpdating(ByVal sender As Object, ByVal e As DetailsViewUpdateEventArgs) Handles CustomerDetailsView.ItemUpdating
' Validate the field values entered by the user. This
' example determines whether the user left any fields
' empty. Use the NewValues property to access the new
' values entered by the user.
Dim emptyFieldList As ArrayList = ValidateFields(CType(e.NewValues, IOrderedDictionary))
If emptyFieldList.Count > 0 Then
' The user left some fields empty. Display an error message.
' Use the Keys property to retrieve the key field value.
Dim keyValue As String = e.Keys("CustomerID").ToString()
MessageLabel.Text = "You must enter a value for all fields of record " & _
keyValue & ".<br/>The following fields are missing:<br/><br/>"
' Display the missing fields.
Dim value As String
For Each value In emptyFieldList
' Use the OldValues property access the original value
' of a field.
MessageLabel.Text &= value & " - Original Value = " & _
e.OldValues(value).ToString() & "<br />"
Next
' Cancel the update operation.
e.Cancel = True
Else
' The field values passed validation. Clear the
' error message label.
MessageLabel.Text = ""
End If
End Sub
Function ValidateFields(ByVal list As IOrderedDictionary) As ArrayList
' Create an ArrayList object to store the
' names of any empty fields.
Dim emptyFieldList As New ArrayList()
' Iterate though the field values entered by
' the user and check for an empty field. Empty
' fields contain a null value.
Dim entry As DictionaryEntry
For Each entry In list
If entry.Value Is Nothing Then
' Add the field name to the ArrayList object.
emptyFieldList.Add(entry.Key.ToString())
End If
Next
Return emptyFieldList
End Function
Sub CustomerDetailsView_ModeChanging(ByVal sender As Object, ByVal e As DetailsViewModeEventArgs) Handles CustomerDetailsView.ModeChanging
If e.CancelingEdit Then
' The user canceled the update operation.
' Clear the error message label.
MessageLabel.Text = ""
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DetailsViewUpdateEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DetailsViewUpdateEventHandler Example</h3>
<asp:detailsview id="CustomerDetailsView"
datasourceid="DetailsViewSource"
autogeneraterows="true"
autogenerateeditbutton="true"
allowpaging="true"
datakeynames="CustomerID"
runat="server">
<pagersettings position="Bottom"/>
</asp:detailsview>
<br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Northwind sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the web.config file. -->
<asp:sqldatasource id="DetailsViewSource"
selectcommand="Select [CustomerID], [CompanyName], [Address],
[City], [PostalCode], [Country] From [Customers]"
updatecommand="Update [Customers] Set
[CompanyName]=@CompanyName, [Address]=@Address,
[City]=@City, [PostalCode]=@PostalCode,
[Country]=@Country
Where [CustomerID]=@CustomerID"
connectionstring=
"<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Poznámky
Ovládací DetailsView prvek vyvolá ItemUpdating událost, když se v ovládacím prvku klikne tlačítko Update (tlačítko s CommandName jeho vlastností nastavenou na "Update") v ovládacím prvku, ale před tím, než DetailsView ovládací prvek aktualizuje záznam. To vám umožní poskytnout obslužnou rutinu události, která provádí vlastní rutinu, jako je například kódování HTML hodnoty záznamu před aktualizací ve zdroji dat, kdykoli dojde k této události.
Při vytváření delegáta DetailsViewUpdateEventHandler identifikujete metodu, která bude zpracovávat událost. Pokud chcete událost přidružit k obslužné rutině události, přidejte do události instanci delegáta. Obslužná rutina události se volá při každém výskytu události, pokud delegáta neodeberete. Další informace o delegátech obslužné rutiny událostí naleznete v tématu Zpracování a vyvolávání událostí.
Metody rozšíření
| Name | Description |
|---|---|
| GetMethodInfo(Delegate) |
Získá objekt, který představuje metodu reprezentovanou zadaným delegátem. |
