Control.CausesValidation Proprietà
Definizione
Ottiene o imposta un valore che indica se viene eseguita la convalida di tutti i controlli per cui è richiesta quando il controllo riceve lo stato attivo.Gets or sets a value indicating whether the control causes validation to be performed on any controls that require validation when it receives focus.
public:
property bool CausesValidation { bool get(); void set(bool value); };
public bool CausesValidation { get; set; }
member this.CausesValidation : bool with get, set
Public Property CausesValidation As Boolean
Valore della proprietà
true
se viene eseguita la convalida di tutti i controlli per cui è richiesta quando il controllo riceve lo stato attivo; in caso contrario, false
.true
if the control causes validation to be performed on any controls requiring validation when it receives focus; otherwise, false
. Il valore predefinito è true
.The default is true
.
Esempi
Nell'esempio di codice seguente viene usata la classe derivata TextBox e viene convalidato un indirizzo di posta elettronica immesso dall'utente.The following code example uses the derived class TextBox and validates an email address that the user enters. Se l'indirizzo di posta elettronica non è nel formato standard (che contiene "@" and ""), la convalida ha esito negativo, viene visualizzata un'icona ErrorProvider e l'evento viene annullato.If the email address is not in the standard format (containing "@" and "."), the validation fails, an ErrorProvider icon is displayed, and the event is canceled. Uno dei pulsanti nel form ha la proprietà CausesValidation impostata su false
.One of the buttons on the form has its CausesValidation property set to false
. Quando si fa clic o si imposta lo stato attivo su questo pulsante non viene attivata la convalida.Clicking or setting focus to this button does not trigger validation. Questo esempio richiede che sia stato creato un controllo TextBox, un ErrorProvider e un Button in un modulo.This example requires that a TextBox, an ErrorProvider control, and a Button have been created on a form.
public:
Form1()
{
InitializeComponent();
//Set button2 to be non-validating.
this->button2->CausesValidation = false;
}
private:
void textBox1_Validating( Object^ sender, System::ComponentModel::CancelEventArgs^ e )
{
String^ errorMsg;
if ( !ValidEmailAddress( textBox1->Text, &errorMsg ) )
{
// Cancel the event and select the text to be corrected by the user.
e->Cancel = true;
textBox1->Select( 0, textBox1->Text->Length );
// Set the ErrorProvider error with the text to display.
this->errorProvider1->SetError( textBox1, errorMsg );
}
}
void textBox1_Validated( Object^ sender, System::EventArgs^ e )
{
// If all conditions have been met, clear the ErrorProvider of errors.
errorProvider1->SetError( textBox1, "" );
}
public:
bool ValidEmailAddress( String^ emailAddress, [Out]interior_ptr<String^> errorMessage )
{
// Confirm that the email address String* is not empty.
if ( emailAddress->Length == 0 )
{
*errorMessage = "email address is required.";
return false;
}
// Confirm that there is an "@" and a "." in the email address, and in the correct order.
if ( emailAddress->IndexOf( "@" ) > -1 )
{
if ( emailAddress->IndexOf( ".", emailAddress->IndexOf( "@" ) ) > emailAddress->IndexOf( "@" ) )
{
*errorMessage = "";
return true;
}
}
*errorMessage = "email address must be valid email address format.\n" +
"For example 'someone@example.com' ";
return false;
}
public Form1()
{
InitializeComponent();
//Set button2 to be non-validating.
this.button2.CausesValidation = false;
}
private void textBox1_Validating(object sender,
System.ComponentModel.CancelEventArgs e)
{
string errorMsg;
if(!ValidEmailAddress(textBox1.Text, out errorMsg))
{
// Cancel the event and select the text to be corrected by the user.
e.Cancel = true;
textBox1.Select(0, textBox1.Text.Length);
// Set the ErrorProvider error with the text to display.
this.errorProvider1.SetError(textBox1, errorMsg);
}
}
private void textBox1_Validated(object sender, System.EventArgs e)
{
// If all conditions have been met, clear the ErrorProvider of errors.
errorProvider1.SetError(textBox1, "");
}
public bool ValidEmailAddress(string emailAddress, out string errorMessage)
{
// Confirm that the email address string is not empty.
if(emailAddress.Length == 0)
{
errorMessage = "email address is required.";
return false;
}
// Confirm that there is an "@" and a "." in the email address, and in the correct order.
if(emailAddress.IndexOf("@") > -1)
{
if(emailAddress.IndexOf(".", emailAddress.IndexOf("@") ) > emailAddress.IndexOf("@") )
{
errorMessage = "";
return true;
}
}
errorMessage = "email address must be valid email address format.\n" +
"For example 'someone@example.com' ";
return false;
}
Public Sub New()
MyBase.New()
InitializeComponent()
'Set button2 to be non-validating.
Me.button2.CausesValidation = False
End Sub
Private Function ValidEmailAddress(ByVal emailAddress As String, ByRef errorMessage As String) As Boolean
' Confirm there is text in the control.
If textBox1.Text.Length = 0 Then
errorMessage = "Email address is required."
Return False
End If
' Confirm that there is an "@" and a "." in the email address, and in the correct order.
If emailAddress.IndexOf("@") > -1 Then
If (emailAddress.IndexOf(".", emailAddress.IndexOf("@")) > emailAddress.IndexOf("@")) Then
errorMessage = ""
Return True
End If
End If
errorMessage = "Email address must be valid email address format." + ControlChars.Cr + _
"For example 'someone@example.com' "
Return False
End Function
Private Sub textBox1_Validating(ByVal sender As Object, _
ByVal e As System.ComponentModel.CancelEventArgs) Handles textBox1.Validating
Dim errorMsg As String
If Not ValidEmailAddress(textBox1.Text, errorMsg) Then
' Cancel the event and select the text to be corrected by the user.
e.Cancel = True
textBox1.Select(0, textBox1.Text.Length)
' Set the ErrorProvider error with the text to display.
Me.errorProvider1.SetError(textBox1, errorMsg)
End If
End Sub
Private Sub textBox1_Validated(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles textBox1.Validated
' If all conditions have been met, clear the error provider of errors.
errorProvider1.SetError(textBox1, "")
End Sub
Commenti
Se la proprietà CausesValidation è impostata su false
, gli eventi Validating e Validated vengono eliminati.If the CausesValidation property is set to false
, the Validating and Validated events are suppressed.
Il valore della proprietà CausesValidation viene in genere impostato su false
per i controlli, ad esempio un pulsante?.The CausesValidation property value is typically set to false
for controls such as a Help button.