ObjectDataSourceView.Updating Evento
Definição
Importante
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Ocorre antes de uma Update operação.
public:
event System::Web::UI::WebControls::ObjectDataSourceMethodEventHandler ^ Updating;public event System.Web.UI.WebControls.ObjectDataSourceMethodEventHandler Updating;member this.Updating : System.Web.UI.WebControls.ObjectDataSourceMethodEventHandler Public Custom Event Updating As ObjectDataSourceMethodEventHandler Tipo de Evento
Exemplos
O exemplo de código seguinte demonstra como usar um DropDownList controlo, TextBox controlos e vários ObjectDataSource controlos para atualizar dados. Apresenta DropDownList o nome de um NorthwindEmployee, enquanto os TextBox controlos são usados para introduzir e atualizar informações de endereço. Como a UpdateParameters coleção contém um ControlParameter objeto associado ao valor selecionado do DropDownList, o botão que desencadeia a Update operação só é ativado depois de um funcionário ser selecionado.
<%@ 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();
}
// Dynamically add parameters to the InputParameters collection.
private void NorthwindEmployeeUpdating(object source, ObjectDataSourceMethodEventArgs e) {
// The names of the parameters are the same as
// the variable names for the method that is invoked to
// perform the Update. The InputParameters collection is
// an IDictionary collection of name/value pairs,
// not a ParameterCollection.
e.InputParameters.Add("anID", DropDownList1.SelectedValue);
e.InputParameters.Add("anAddress" ,AddressBox.Text);
e.InputParameters.Add("aCity" ,CityBox.Text);
e.InputParameters.Add("aPostalCode",PostalCodeBox.Text);
}
</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. -->
<asp:objectdatasource
id="ObjectDataSource2"
runat="server"
updatemethod="UpdateEmployeeWrapper"
onupdating="NorthwindEmployeeUpdating"
typename="Samples.AspNet.CS.EmployeeLogic" />
<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
' Dynamically add parameters to the InputParameters collection.
Private Sub NorthwindEmployeeUpdating(source As Object, e As ObjectDataSourceMethodEventArgs)
' The names of the parameters are the same as
' the variable names for the method that is invoked to
' perform the Update. The InputParameters collection is
' an IDictionary collection of name/value pairs,
' not a ParameterCollection.
e.InputParameters.Add("anID", DropDownList1.SelectedValue)
e.InputParameters.Add("anAddress" ,AddressBox.Text)
e.InputParameters.Add("aCity" ,CityBox.Text)
e.InputParameters.Add("aPostalCode",PostalCodeBox.Text)
End Sub ' NorthwindEmployeeUpdating
</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. -->
<asp:objectdatasource
id="ObjectDataSource2"
runat="server"
updatemethod="UpdateEmployeeWrapper"
onupdating="NorthwindEmployeeUpdating"
typename="Samples.AspNet.VB.EmployeeLogic" />
<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>
Observações
Trate do Updating evento para realizar operações adicionais de inicialização específicas da sua aplicação, para validar os valores dos parâmetros ou para alterar os valores dos parâmetros antes do ObjectDataSource controlo realizar a Update operação. Os parâmetros estão disponíveis como uma IDictionary coleção, acedida pela InputParameters propriedade que é exposta pelo ObjectDataSourceMethodEventArgs objeto.
Para mais informações sobre como gerir eventos, consulte Gestão e Levantamento de Eventos.