按钮仅在第二次单击时起作用

问题描述 投票：0回答：5

我正在尝试创建一个连接到数据库的 ASP.NET 基本站点。它应该允许用户注册和登录。

我使用 javascript 检查输入并检查后面的代码，以防它被禁用。

问题是，每当我第一次单击注册、登录或注销按钮时，它们都不起作用；页面保持不变。 然而，第二次，它们就完美地工作了。 调试器说它被调用了两次。

有什么想法吗？

ASP：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Main.aspx.cs" 
Inherits="Register_and_Login.Main" %>
<!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">
<script type="text/javascript">
    function isUserValid() {
    var UserLength = document.getElementById("UserTB").value.length;
    var ValidatorLabel = document.getElementById("ValidateUser");
    if (UserLength < 6 || UserLength > 15) {
        ValidatorLabel.style.display = 'inline';
        return false;
        }
    else {
        ValidatorLabel.style.display = 'none';
        return true;
    }  
    }
    function isPassValid() {
        var PassLength = document.getElementById("PasswordTB").value.length;
        var ValidatorLabel = document.getElementById("ValidatePassword");
        if (PassLength < 6 || PassLength > 15) {
            ValidatorLabel.style.display = 'inline';
            return false;
        }
        else {
            ValidatorLabel.style.display = 'none';
            return true;
        } 
    }
    function isConfirmValid() {
        var Password = document.getElementById("PasswordTB").value;
        var Me = document.getElementById("ConfirmTB").value;
        var ValidatorLabel = document.getElementById("ValidateConfirm");
        if (Password == Me) {
            ValidatorLabel.style.display = 'none';
            return true;
        }
        else {
            ValidatorLabel.style.display = 'inline';
            return false;
        }
    }
    function isEmailValid() {
        var str = document.getElementById("EmailTB").value;
        var lastAtPos = str.lastIndexOf('@');
        var lastDotPos = str.lastIndexOf('.');
        var isFine = (lastAtPos < lastDotPos && lastAtPos > 0 && str.indexOf('@@') == -1 && lastDotPos > 2 && (str.length - lastDotPos) > 2);
        var ValidationLabel=document.getElementById("ValidateEmail");
        if(isFine)
        {
            ValidationLabel.style.display='none';
            return true;
        }
        else
        {
            ValidationLabel.style.display='inline';
            return false;
        }
    }
</script>
<title></title>
<style type="text/css">
    .Validators
    {
        display:none;
    }
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
    <asp:Panel id="RegisterRelated" runat="server">
    Username:<br />
    <asp:TextBox ID="UserTB" runat="server" OnChange="isUserValid()" AutoPostBack="false"></asp:TextBox>
    <asp:Label ID="ValidateUser" runat="server" ForeColor="Red" 
        Text="Username must be 6-15 characters in length, and contain no special characters." CssClass="Validators"></asp:Label>
    <br />
    Password:<br />
    <asp:TextBox ID="PasswordTB" runat="server" OnChange="isPassValid()" AutoPostBack="false"></asp:TextBox>
    <asp:Label ID="ValidatePassword" runat="server" ForeColor="Red" 
        Text="Password must be 6-15 characters in length, and contain no special characters." CssClass="Validators"></asp:Label>
    <br />
    Confirm password:<br />
    <asp:TextBox ID="ConfirmTB" runat="server" OnChange="isConfirmValid()" AutoPostBack="false"></asp:TextBox>
    <asp:Label ID="ValidateConfirm" runat="server" ForeColor="Red" 
        Text="This field must match the password field." CssClass="Validators"></asp:Label>
    <br />
    Email:<br />
    <asp:TextBox ID="EmailTB" runat="server" OnChange="isEmailValid()" AutoPostBack="false"></asp:TextBox>
    <asp:Label ID="ValidateEmail" runat="server" ForeColor="Red" Text="Invalid Email." CssClass="Validators"></asp:Label>
    <br />
    <br />
    <asp:Button ID="Register" runat="server" Text="Register" onclick="Register_Click" EnableViewState="false"/>
    <br />
    <asp:Panel ID="Answer" runat="server" >
    </asp:Panel>
    </asp:Panel>
    <br />
    <br />
    <asp:Panel id="LoginRelated" runat="server">
    User: 
    <asp:TextBox ID="LoginUserTB" runat="server" AutoPostBack="false"></asp:TextBox>
    <br />
    Password:
    <asp:TextBox ID="LoginPassTB" runat="server" AutoPostBack="false"></asp:TextBox>
        <br />
    <asp:Button ID="Login" runat="server" Text="Login" onclick="Login_Click" EnableViewState="false" />
    <br />
    </asp:Panel>
    <asp:Panel ID="InPage" runat="server">
    <asp:Panel ID="LogAnswer" runat="server">
    </asp:Panel>
    <br />
    <asp:Label ID="WelcomeTag" runat="server"></asp:Label>

        <br />
        <br />
        <asp:Button ID="logout" runat="server" onclick="logout_Click" Text="Logout" EnableViewState="false"/>

    </asp:Panel>
</div>
</form>
</body>
</html>

C# 登录、注销和注册按钮：

protected void Register_Click(object sender, EventArgs e)
    {
        Label Reply = new Label();
        if (Session["User"] == null)
        {
            Result myRegResult = Result.IN_PROG;
            User myAddedUser = new User(UserTB.Text, PasswordTB.Text, EmailTB.Text);
            DbManager.OpenDbConnection();
            myRegResult = DbManager.Register(myAddedUser); //Connection with the database.
            Reply.Text = resultToString(myRegResult);
            Reply.ForeColor = resultColor(myRegResult);
        }
        else
        {
            Reply.Text = "You must log out before you register.";
            Reply.ForeColor = resultColor(Result.EXEC_ERROR);
        }
        Answer.Controls.Add((Control)Reply);
        //Reset_Fields();
    }


protected void Login_Click(object sender, EventArgs e)
    {
        Label Reply = new Label();
        LoginProc Status = LoginProc.IN_PROG;
        DbManager.OpenDbConnection();
        Status = DbManager.Login(LoginUserTB.Text, LoginPassTB.Text); //Connection with the database
        Reply.Text = ProcToString(Status);
        Reply.ForeColor = ProcToColor(Status);
        LogAnswer.Controls.Add(Reply);
        if (Status == LoginProc.FINE)
           Session["User"] = new User(LoginUserTB.Text, LoginPassTB.Text, null);
        //Reset_Fields();
    }



protected void logout_Click(object sender, EventArgs e)
    {
        Session["User"] = null;

    }

页面加载：

protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["User"] != null)
        {
            RegisterRelated.Visible = false;
            LoginRelated.Visible = false;
            InPage.Visible = true;
            WelcomeTag.Text = "Welcome, " + ((User)Session["User"]).Username + ".";
        }
        else
        {
            RegisterRelated.Visible = true;
            LoginRelated.Visible = true;
            WelcomeTag.Text = String.Empty;
            InPage.Visible = false;
        }
    }

编辑：我的一个朋友建议我看一下 ASP.NET 页面生命周期，如果它对任何人有帮助的话，它可能与页面呈现后完成的数据库交互有关。

c# asp.net button
5个回答
2
投票

你的朋友是对的，你需要更好地理解页面的Page Life周期。基本上在这种情况下，您需要了解 OnLoad 事件发生在任何单击事件之前。您可以通过向 OnLoad 事件和单击处理程序添加断点来亲自查看这一点。您将看到事件发生的顺序。 在这种情况下，我将编写一个方法来设置页面，然后在每个单击事件中调用它

private void setUpPage() { if (Session["User"] != null) { RegisterRelated.Visible = false; LoginRelated.Visible = false; InPage.Visible = true; WelcomeTag.Text = "Welcome, " + ((User)Session["User"]).Username + "."; } else { RegisterRelated.Visible = true; LoginRelated.Visible = true; WelcomeTag.Text = String.Empty; InPage.Visible = false; } } protected void Page_Load(object sender, EventArgs e) { //Call if not in response to button click if(!IsPostBack) { setUpPage(); } } protected void Register_Click(object sender, EventArgs e) { Label Reply = new Label(); if (Session["User"] == null) { Result myRegResult = Result.IN_PROG; User myAddedUser = new User(UserTB.Text, PasswordTB.Text, EmailTB.Text); DbManager.OpenDbConnection(); myRegResult = DbManager.Register(myAddedUser); //Connection with the database. Reply.Text = resultToString(myRegResult); Reply.ForeColor = resultColor(myRegResult); } else { Reply.Text = "You must log out before you register."; Reply.ForeColor = resultColor(Result.EXEC_ERROR); } Answer.Controls.Add((Control)Reply); //Reset_Fields(); //Reset the fields as required AFTER you have done what you need with the database setUpPage(); } protected void Login_Click(object sender, EventArgs e) { Label Reply = new Label(); LoginProc Status = LoginProc.IN_PROG; DbManager.OpenDbConnection(); Status = DbManager.Login(LoginUserTB.Text, LoginPassTB.Text); //Connection with the database Reply.Text = ProcToString(Status); Reply.ForeColor = ProcToColor(Status); LogAnswer.Controls.Add(Reply); if (Status == LoginProc.FINE) Session["User"] = new User(LoginUserTB.Text, LoginPassTB.Text, null); //Reset_Fields(); //Reset the fields as required AFTER you have done what you need with the database setUpPage(); } protected void logout_Click(object sender, EventArgs e) { Session["User"] = null; //Reset the fields as required AFTER you have done what you need with the database setUpPage(); } 




      

      
      
      

      

        

          

            

              
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投票

              
            

          

        

        
after
按钮单击事件起作用。

我可以看到，您在页面加载事件中设置为页面显示，并在按钮单击事件中设置为会话值。因此，第一次点击时，首先触发页面加载事件，但还没有 Session 值。页面加载事件完成并通过按钮单击事件恢复，因此会话值现在不为空（如果输入的用户信息有效）。
这就是页面在第二次点击时工作的原因。



解决方案：


protected void Page_Load(object sender, EventArgs e)
    {
        if (this.IsPostBack) //just write this
                return;

        if (Session["User"] != null)
        {
            RegisterRelated.Visible = false;
            LoginRelated.Visible = false;
            InPage.Visible = true;
            WelcomeTag.Text = "Welcome, " + ((User)Session["User"]).Username + ".";
        }
        else
        {
            RegisterRelated.Visible = true;
            LoginRelated.Visible = true;
            WelcomeTag.Text = String.Empty;
            InPage.Visible = false;
        }
    }




注意：我得到了你的代码并尝试过。



另请参阅：
http://msdn.microsoft.com/en-us/library/ms178472%28v=vs.85%29.aspx

    




      

      
      
      

      

        

          

            

              
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Page_BlockSubmit = false;
之前尝试
return false;
    





      

      
      
      

      

        

          

            

              
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