Control.Validating 事件
重要
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在控件验证时发生。
public:
event System::ComponentModel::CancelEventHandler ^ Validating;C#
public event System.ComponentModel.CancelEventHandler Validating;C#
public event System.ComponentModel.CancelEventHandler? Validating;member this.Validating : System.ComponentModel.CancelEventHandler Public Custom Event Validating As CancelEventHandler 下面的代码示例使用派生类 TextBox 并验证用户输入的电子邮件地址。 如果电子邮件地址不是标准格式， (包含“@”和“”。) ，验证失败，显示图标 ErrorProvider 并取消事件。 此示例要求 TextBox 已在窗体上创建 和 ErrorProvider 控件。
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;
}
C#
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;
}
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
通过使用键盘 (TAB、SHIFT+TAB 等) 、调用 Select 或 SelectNextControl 方法或将 属性设置为 ContainerControl.ActiveControl 当前窗体来更改焦点时，焦点事件按以下顺序发生：
使用鼠标或调用 Focus 方法更改焦点时，焦点事件按以下顺序发生：
如果 属性 CausesValidation 设置为 false， Validating 则取消和 Validated 事件。
Cancel如果在事件委托中Validating将 的 CancelEventArgs 属性设置为 true ，则通常会在事件后Validating发生的所有事件都会被禁止显示。
注意
不要尝试从 、、GotFocus、ValidatingLeaveLostFocus、 或 Validated 事件处理程序中Enter设置焦点。 这样做可能会导致应用程序或操作系统停止响应。 有关详细信息，请参阅 WM_KILLFOCUS “键盘输入参考”部分中的主题和 关于消息和消息队列 一文的“消息死锁”部分。
有关处理事件的详细信息，请参阅 处理和引发事件。
| 产品 | 版本 |
|---|---|
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| Windows Desktop | 3.0, 3.1, 5, 6, 7, 8, 9, 10 |
