如果条件为真，代码不会返回答案

【问题标题】：Code does not return if the condition is true如果条件为真，代码不会返回
【发布时间】：2012-04-02 02:19:50
【问题描述】：

我需要验证用户提供的信息是否在数据库中，我尝试输入正确的条件，但它不工作它返回一个在数据库中找不到的错误。你能检查我的代码并告诉我发生了什么吗？，我尝试调试它，但 foreach 循环继续循环并且没有转到 if (isexist) 语句

protected void btnSubmit_Click(object sender, EventArgs e)
    {
        token = FormsAuthentication.HashPasswordForStoringInConfigFile(txtUsername.Text.ToString() + txtAcctNo.Text.ToString(), "MD5");
        try
        {
            bool isExist = false;
            DataSet ds = new DataSet();
            ds = startService.getAllUsersWithoutFilter();
            if (ds.Tables[0].Rows.Count > 0)
            {
                foreach (DataRow dRow in ds.Tables[0].Rows)
                {

                    string userName = dRow["UserName"].ToString();
                    string acctNo = dRow["AccountNumber"].ToString();
                    string question = dRow["SecretQuestion"].ToString();
                    string answer = dRow["SecretAnswer"].ToString();

                    if (userName == txtUsername.Text.ToString() && acctNo == txtAcctNo.Text.ToString() && question == cboQuestion.Text.ToString() &&  answer == txtAnswer.Text.ToString())
                    {
                        isExist = true;
                    }
                    else
                    {
                        isExist = false;
                    }

                }

                if (isExist)
                {
                    startService.sendTokenizer(txtUsername.Text.ToString(), token);
                    //update database to change password to standard password
                    startService.inserUserActivity(txtUsername.Text.ToString(), txtAcctNo.Text.ToString(), "Password Reset Request", HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]);
                    startService.requestReset(txtUsername.Text.ToString(), txtAcctNo.Text.ToString(), token);

                    lblMessage.ForeColor = System.Drawing.Color.Green;
                    lblMessage.Text = "<br>We have sent an email to you for the instructions to reset your password. Please check your email.";
                }
                else
                {
                    this.lblMessage.ForeColor = System.Drawing.Color.Red;
                    this.lblMessage.Text = "<br><br>Error - Information cannot be found. Please check and try again. Make sure all the fields are correct.";
                }

            }
        }
        catch
        {
            lblError.Text = "There was an error occured while processing your request. Please try again later.";
        }

    }

【问题讨论】：

标签： c# asp.net sql-server database web-services

【解决方案1】：

我认为当你将 isExist 设置为 true 时，你需要的只是打破你的 foreach 循环。

if (userName == txtUsername.Text.ToString() && acctNo == txtAcctNo.Text.ToString() && question == cboQuestion.Text.ToString() &&  answer == txtAnswer.Text.ToString())
{
    isExist = true;
    break; //Found it, so stop looking.
}

【讨论】：

【解决方案2】：

我认为 Joel 对您的问题的直接回答是正确的。

我要补充一点，您应该重新考虑加载整个用户表并在 Web 服务器上对其进行迭代。为什么不尝试从数据库中选择匹配的行呢？如果您得到匹配，则凭证是有效的。如果不是，则它们无效。

【讨论】：

+1 - 绝对是一个好主意，不要加载整个表，而是利用数据库的力量找到匹配的行进行验证。

【解决方案3】：

@Dhenn：您需要在代码中进行以下更改

protected void btnSubmit_Click(object sender, EventArgs e)
{
    token = FormsAuthentication.HashPasswordForStoringInConfigFile(txtUsername.Text.ToString() + txtAcctNo.Text.ToString(), "MD5");
    try
    {
        bool isExist = false;
        DataSet ds = new DataSet();
        ds = startService.getAllUsersWithoutFilter();
        if (ds.Tables[0].Rows.Count > 0)
        {
            foreach (DataRow dRow in ds.Tables[0].Rows)
            {

                string userName = dRow["UserName"].ToString();
                string acctNo = dRow["AccountNumber"].ToString();
                string question = dRow["SecretQuestion"].ToString();
                string answer = dRow["SecretAnswer"].ToString();

                if (userName == txtUsername.Text.ToString() && acctNo == txtAcctNo.Text.ToString() && question == cboQuestion.Text.ToString() &&  answer == txtAnswer.Text.ToString())
                {
                     // if exist execute following code

                    startService.sendTokenizer(txtUsername.Text.ToString(), token);
                //update database to change password to standard password
                startService.inserUserActivity(txtUsername.Text.ToString(), txtAcctNo.Text.ToString(), "Password Reset Request", HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]);
                startService.requestReset(txtUsername.Text.ToString(), txtAcctNo.Text.ToString(), token);

                lblMessage.ForeColor = System.Drawing.Color.Green;
                lblMessage.Text = "<br>We have sent an email to you for the instructions to reset your password. Please check your email.";
                }
                else
                {
                  // id not exist then execute following code

                   this.lblMessage.ForeColor = System.Drawing.Color.Red;
                this.lblMessage.Text = "<br><br>Error - Information cannot be found. Please check and try again. Make sure all the fields are correct.";
                }

            }              

        }
    }
    catch
    {
        lblError.Text = "There was an error occured while processing your request. Please try again later.";
    }

}

【讨论】：