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CustomValidator.EvaluateIsValid Metode

  • Referensi

Definisi

Ruang nama:
System.Web.UI.WebControls
Rakitan:
System.Web.dll

Mengambil alih EvaluateIsValid() metode .

protected:
 override bool EvaluateIsValid();
protected override bool EvaluateIsValid ();
override this.EvaluateIsValid : unit -> bool
Protected Overrides Function EvaluateIsValid () As Boolean

Mengembalikan

Boolean

true jika nilai dalam kontrol input valid; jika tidak, false.

Contoh

Contoh kode berikut menunjukkan cara mengambil alih EvaluateIsValid metode dalam kontrol server kustom.

Penting

Contoh ini memiliki kotak teks yang menerima input pengguna, yang merupakan potensi ancaman keamanan. Secara default, ASP.NET halaman Web memvalidasi bahwa input pengguna tidak menyertakan elemen skrip atau HTML. Untuk informasi selengkapnya, lihat Gambaran Umum Eksploitasi Skrip.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom CustomValidator - EvaluateIsValid - C# Example</title>
  </head>
<body>
  <form id="Form1" method="post" runat="server">
    <h3>Custom CustomValidator - EvaluateIsValid - C# Example</h3>

    <asp:Label id="Label1" runat="server" Text="Enter an even number:"
      AssociatedControlID="TextBox1" /><br />

    <asp:TextBox id="TextBox1" runat="server" /> 

    <aspSample:CustomCustomValidatorEvaluateIsValid
      id="Customvalidator1"
      runat="server"
      ControlToValidate="TextBox1"
      Display="Static"
      ErrorMessage="Not an even number!" /><br /><br />

    <asp:Button id="Button1" runat="server" Text="Validate" />

  </form>
</body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom CustomValidator - EvaluateIsValid - VB.NET Example</title>
  </head>
<body>
  <form id="Form1" method="post" runat="server">
    <h3>Custom CustomValidator - EvaluateIsValid - VB.NET Example</h3>
    <asp:Label id="Label1" runat="server" Text="Enter an even number:"
      AssociatedControlID="TextBox1" /><br />
    <asp:TextBox id="TextBox1" runat="server" /> 
    <aspSample:CustomCustomValidatorEvaluateIsValid id="Customvalidator1" runat="server" ControlToValidate="TextBox1" Display="Static" ErrorMessage="Not an even number!" /><br /><br />
    <asp:Button id="Button1" runat="server" Text="Validate" />
  </form>
</body>
</html>

using System.Web;
using System.Security.Permissions;

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomCustomValidatorEvaluateIsValid : System.Web.UI.WebControls.CustomValidator
    {
        protected override bool EvaluateIsValid()
        {
            bool isValid = false;
            
            // Get the name of the control to validate.
            string controlToValidate = this.ControlToValidate;
            if (controlToValidate.Length > 0) 
            {
            // Get the control's value.
            string controlValue = GetControlValidationValue(controlToValidate);

            // If the value is not null and not empty, test whether 
            // check if the value entered into the text box is even,
            // if so return true, else return false in all other cases.
            if ((controlValue != null) && (!controlValue.Trim().Equals(System.String.Empty)))
            {
                try 
                {
                int i = int.Parse(controlValue);
                isValid = ((i%2) == 0);
                }
                catch
                {}
            }  
            } 
            return isValid;   
        }
    }
}

Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls
    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomCustomValidatorEvaluateIsValid
        Inherits System.Web.UI.WebControls.CustomValidator

        Protected Overrides Function EvaluateIsValid() As Boolean
            Dim isValid As Boolean = False

            ' Get the name of the control to validate.
            Dim controlToValidate As String = Me.ControlToValidate
            If controlToValidate.Length > 0 Then

                ' Get the control's value.
                Dim controlValue As String = GetControlValidationValue(controlToValidate)

                ' If the value is not null and not empty, test whether 
                ' check if the value entered into the text box is even,
                ' if so return true, else return false in all other cases.
                If Not (controlValue Is Nothing) AndAlso _
                   Not controlValue.Trim().Equals(System.String.Empty) Then
                    Try
                        Dim i As Integer = Integer.Parse(controlValue)
                        isValid = ((i Mod 2) = 0)
                    Catch
                    End Try
                End If
            End If
            Return isValid
        End Function

    End Class
End Namespace

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