Control.CausesValidation Control.CausesValidation Control.CausesValidation Control.CausesValidation Property

定義

取得或設定值,指出控制項取得焦點時,是否會在任何需要驗證的控制項上執行驗證。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

屬性值

如果控制項取得焦點時會在需要驗證的任何控制項上執行驗證,則為 true,否則為 falsetrue if the control causes validation to be performed on any controls requiring validation when it receives focus; otherwise, false. 預設為 trueThe default is true.

範例

下列程式碼範例會使用衍生類別TextBox ,並驗證使用者輸入的電子郵件地址。The following code example uses the derived class TextBox and validates an email address that the user enters. 如果電子郵件地址不是標準格式(包含 "@" and "."),驗證就會失敗ErrorProvider 、顯示圖示,並取消事件。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. 表單上的其中一個按鈕會將CausesValidation其屬性設定false為。One of the buttons on the form has its CausesValidation property set to false. 按一下或設定此按鈕的焦點,並不會觸發驗證。Clicking or setting focus to this button does not trigger validation. 這個範例需要TextBox在表單上ErrorProvider建立、控制項和ButtonThis 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

備註

如果屬性設定為false,則Validating會隱藏和Validated事件。 CausesValidationIf the CausesValidation property is set to false, the Validating and Validated events are suppressed.

控制項CausesValidation的屬性值通常會設定false為,例如 [說明] 按鈕。The CausesValidation property value is typically set to false for controls such as a Help button.

適用於

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