String.Empty在单击按钮时不起作用

Question

I am trying to clear the form on cancel button click with a function clearForm() that uses String.Empty with each field of the form but this is not working. 我正在尝试使用函数clearForm（）来清除“取消”按钮上的表单，该函数将String.Empty与表单的每个字段一起使用，但这不起作用。 I am neither getting any error nor getting the expected result. 我既没有收到任何错误，也没有得到预期的结果。

Here's my design code: 这是我的设计代码：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="AddEmployee.aspx.cs" Inherits="AddEmployee" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajax" %>
<!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 id="Head1" runat="server">
    <title>Add Employee</title>
<link href="css/Style.css" type="text/css" rel="Stylesheet" />
</head>
<body>
    <form id="form1" runat="server">
    <ajax:ToolkitScriptManager ID="toolkit1" runat="server"></ajax:ToolkitScriptManager>
    <div>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>
        <table align="center" class="loginBox">
            <tr>
                <th colspan="2" style="color:White; font-size:medium; padding-bottom:10px;" align="left">Personal Information</th>
            </tr>
            <tr>
                <td>Name:</td>
                <td><asp:TextBox ID="txtName" CssClass="signup_textbox" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="reqName" ControlToValidate="txtName" runat="server" Display="None" ErrorMessage="Name" ></asp:RequiredFieldValidator>
                </td>
            </tr>
            <tr>
                <td>Address</td>
                <td><asp:TextBox TextMode="MultiLine" Height="40" Width="135" ID="txtAddress" CssClass="signup_textbox" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="reqAdd" ControlToValidate="txtAddress" runat="server" Display="None" ErrorMessage="Address" ></asp:RequiredFieldValidator>
                </td>
            </tr>
            <tr>
                <td>DoB:</td>
                <td>
                    <asp:TextBox ID="txtDoB" CssClass="signup_textbox cal_box" runat="server" />
                    <ajax:CalendarExtender ID="CalendarExtender1" TargetControlID="txtDoB" Format="dd/MM/yyyy" runat="server"></ajax:CalendarExtender> 
                </td>
            </tr>
            <tr>
                <td>Gender</td>
                <td>
                    <asp:RadioButtonList CssClass="signup_textbox" ID="GenderList" runat="server" RepeatDirection="Horizontal">
                        <asp:ListItem Selected="True">Male</asp:ListItem>
                        <asp:ListItem>Female</asp:ListItem>
                    </asp:RadioButtonList>
                </td>
            </tr>
            <tr>
                <th colspan="2" style="color:White; font-size:medium; padding-bottom:10px;" align="left">Professional Information</th>
            </tr>
            <tr>
                <td>Department:</td>
                <td>
                    <asp:DropDownList ID="ddlDept" CssClass="signup_textbox" runat="server"></asp:DropDownList>
                </td>
            </tr>
            <tr>
                <td>Designation:</td>
                <td><asp:TextBox ID="txtDesig" CssClass="signup_textbox" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="reqDesig" ControlToValidate="txtDesig" runat="server" Display="None" ErrorMessage="Designation" ></asp:RequiredFieldValidator>
                </td>

            </tr>
            <tr>    
                <td>Salary:</td>
                <td><asp:TextBox ID="txtSal" CssClass="signup_textbox" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="reqSal" ControlToValidate="txtSal" runat="server" Display="None" ErrorMessage="Salary" ></asp:RequiredFieldValidator>
                    <asp:RegularExpressionValidator runat="server" id="rexSal" controltovalidate="txtSal" validationexpression="^[0-9]{5}$" errormessage="Salary must be max 5 digits" Display="None" />
                </td>
            </tr>
            <tr>
                <th colspan="2" style="color:White; font-size:medium; padding-bottom:10px;" align="left">Login Information</th>
            </tr>
            <tr>
                <td>Email:</td>
                <td>
                    <asp:TextBox ID="txtEmail" CssClass="signup_textbox" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="reqEmail" ControlToValidate="txtEmail" runat="server" Display="None" ErrorMessage="Email" ></asp:RequiredFieldValidator>
                    <asp:RegularExpressionValidator ID="valEmail" runat="server" ErrorMessage="Invalid Email" ControlToValidate="txtEmail" ValidationExpression="^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$" CssClass="error_msg" Display="none" />
                </td>
            </tr>
            <tr>
                <td>Username:</td>
                <td>
                    <asp:TextBox ID="txtUser" CssClass="signup_textbox" runat="server"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="reqUser" ControlToValidate="txtUser" runat="server" Display="None" EnableClientScript="true" SetFocusOnError="true" ErrorMessage="Username" ></asp:RequiredFieldValidator>
                    <asp:RegularExpressionValidator ID="RegularExpressionValidator1" Display="None" ControlToValidate="txtUser" ValidationExpression="^[\s\S]{3,}$" runat="server" ErrorMessage="Username must have at least 3 characters required."></asp:RegularExpressionValidator>
                </td>
            </tr>
            <tr>
                <td>Password:</td>
                <td><asp:TextBox ID="txtPass" CssClass="signup_textbox" runat="server" TextMode="Password"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="reqPass" ControlToValidate="txtPass" runat="server" Display="None" EnableClientScript="true" SetFocusOnError="true" ErrorMessage="Password" ></asp:RequiredFieldValidator>
                </td>
            </tr>
            <tr>    
                <td>Confirm Password:</td>
                <td><asp:TextBox ID="txtConfPass" CssClass="signup_textbox" runat="server" TextMode="Password"></asp:TextBox>
                    <asp:RequiredFieldValidator ID="reqConfPass" ControlToValidate="txtConfPass" runat="server" Display="None" EnableClientScript="true" SetFocusOnError="true" ErrorMessage="Confirm Password" ></asp:RequiredFieldValidator>
                    <asp:CompareValidator ID="cmpPass" runat="server" ControlToCompare="txtPass" ControlToValidate="txtConfPass" ErrorMessage="Password must match" CssClass="error_msg" Display="None"></asp:CompareValidator>
                </td>
            </tr>
            <tr>
                <td align="center" colspan="2" style="padding:5px;"><span><asp:Button ID="btnRegister" Width="60" runat="server" Text="Register" CssClass="btnLogin" OnClick="btn_AddEmp" /></span>
                                   <span><asp:Button ID="btnClr" Width="60" runat="server" Text="Cancel" CssClass="btnLogin" OnClick="btn_ClearForm" /></span>
                </td>
            </tr>
        </table>
            <asp:Panel ID="errorsPanel" runat="server" Style="display: none; border-style: solid; border-width: thin; border-color: #FFDBCA" Width="175px" BackColor="White">
            <asp:ValidationSummary ID="valSummary" runat="server" CssClass="error_msg" HeaderText="You must enter following" DisplayMode="BulletList" EnableClientScript="true" ShowSummary="true" />
         </asp:Panel>
        </ContentTemplate>
        </asp:UpdatePanel>
            </div>
    </form>
</body>
</html>

Here's my code-behind: 这是我的代码背后：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Globalization;

public partial class AddEmployee : System.Web.UI.Page
{

    protected void Page_Load(object sender, EventArgs e)
    {


    }


    protected void btn_ClearForm(object sender, EventArgs e) //to clear form on IsPostBack or on press of cancel button
    {
        if (!IsPostBack)
        {
            clearForm();
        }
    }

    #region public functions

    public void clearForm()
    {
        txtName.Text = String.Empty;
        txtAddress.Text = String.Empty;
        txtDoB.Text = String.Empty;
        txtDesig.Text = String.Empty;
        txtSal.Text = String.Empty;
        txtEmail.Text = String.Empty;
        txtUser.Text = String.Empty;
        txtPass.Text = String.Empty;
        txtConfPass.Text = String.Empty;
        GenderList.Items[0].Selected = true;
        GenderList.Items[1].Selected = false;
    }

    #endregion

}

Answer 1

There is nothing wrong with string.Empty . string.Empty没有错。 But you do not need condition in btn_ClearForm as btn_ClearForm handler will always called on postback and you put the condition if !IsPostBack 但是您不需要btn_ClearForm条件，因为btn_ClearForm处理程序将始终在回发时调用，并且如果!IsPostBack

// if (!IsPostBack) 
//{
    clearForm();
// }

Your code would be 您的代码将是

protected void btn_ClearForm(object sender, EventArgs e) 
{       
        clearForm();       
}

Answer 2

Got the fix! 解决了！

Just use CausesValidation="false" on the cancel button so as to disable validation upon cancel button click event. 只需在取消按钮上使用CausesValidation =“ false”即可在取消按钮单击事件时禁用验证。

Because when you have used validation on your controls without using CausesValidation="false" on the cancel button, your controls will be forced to pass through validation conditions given to them and since the cancel button is meant to clear your form regardless of checking the validity of the data in form fields, the form will get stuck. 因为当您在控件上使用验证但未在“取消”按钮上使用CausesValidation =“ false”时，您的控件将被迫通过赋予它们的验证条件，并且由于“取消”按钮是为了清除表单而与检查有效性无关表单字段中的数据，表单将被卡住。

So whenever you have used validation conditions on your controls, just make sure you don't get them fired on the click of Cancel/clear/reset button. 因此，无论何时在控件上使用了验证条件，只需确保不要单击“取消/清除/重置”按钮就可以触发它们。

Thanks 谢谢

String.Empty在单击按钮时不起作用

问题描述

2 个解决方案

解决方案1
2 2014-06-27 12:11:22

解决方案2
0 已采纳 2014-07-03 11:46:32

String.Empty在单击按钮时不起作用

问题描述

2 个解决方案

解决方案1 2 2014-06-27 12:11:22

解决方案2 0 已采纳 2014-07-03 11:46:32

解决方案1
2 2014-06-27 12:11:22

解决方案2
0 已采纳 2014-07-03 11:46:32