Control.CausesValidation 属性

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

获取或设置一个值，该值指示控件是否会引起在任何需要在接收焦点时执行验证的控件上执行验证。

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

属性值

Boolean

如果控件引起在任何需要在接收焦点时执行验证的控件上执行验证，则为 true；否则为 false。 默认值为 true。

示例

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。 窗体上的一个按钮的 CausesValidation 属性设置为 false。 单击或设置此按钮的焦点不会触发验证。 此示例要求 TextBox已在窗体上创建 、 ErrorProvider 控件和 Button 。

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

注解

如果 属性 CausesValidation 设置为 false， Validating 则会取消 和 Validated 事件。

对于 CausesValidation 控件（例如“帮助”按钮），属性值通常设置为 false 。

另请参阅

• Validating
• Validated