Question

我试图找出是否有办法在C＃ASP.net中的5个不同if语句中使用单个标签来创建新行。标签为每个未填写的文本框提供错误消息，我试图将所有错误消息放在单独的行上。这是我的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class frmPersonnel : System.Web.UI.Page
{
  protected void Page_Load(object sender, EventArgs e)
  {

  }
  protected void btnSubmit_Click(object sender, EventArgs e)
  {
    bool txtFieldError = false;
    lblError.Text = "";
    txtFirstName.BackColor = System.Drawing.Color.White;
    txtLastName.BackColor = System.Drawing.Color.White;
    txtPayRate.BackColor = System.Drawing.Color.White;
    txtStartDate.BackColor = System.Drawing.Color.White;
    txtEndDate.BackColor = System.Drawing.Color.White;

    if (txtFirstName.Text.Trim() == "")
    {
        txtFieldError = true;
        lblError.Text = lblError.Text + "Must enter first name";
        txtFirstName.BackColor= System.Drawing.Color.Yellow;            
    }

    if (txtLastName.Text.Trim() == "")
    {
        txtFieldError = true;
        lblError.Text = lblError.Text + "Must enter Last name";
        txtLastName.BackColor = System.Drawing.Color.Yellow;
    }

    if (txtPayRate.Text.Trim() == "")
    {
        txtFieldError = true;
        lblError.Text = lblError.Text + "Must enter pay rate";
        txtPayRate.BackColor = System.Drawing.Color.Yellow;
    }

    if (txtStartDate.Text.Trim() == "")
    {
        txtFieldError = true;
        lblError.Text = lblError.Text + "Must enter start date";
        txtStartDate.BackColor = System.Drawing.Color.Yellow;
    }

    if (txtEndDate.Text.Trim() == "")
    {
        txtFieldError = true;
        lblError.Text = lblError.Text + "Must enter end date";
        txtEndDate.BackColor = System.Drawing.Color.Yellow;
    }

    if (!txtFieldError)
    {
        DateTime strDate;
        DateTime nDate;

        strDate = DateTime.Parse(txtStartDate.Text);
        nDate = DateTime.Parse(txtEndDate.Text);

          if (DateTime.Compare(strDate, nDate) >= 0)
          {
           txtFieldError = true;
           lblError.Text = lblError.Text + "Must enter start date earlier than end date";
           txtStartDate.BackColor = System.Drawing.Color.Yellow;
           txtEndDate.BackColor = System.Drawing.Color.Yellow;
          }
    }

    if (!txtFieldError)
    {
        Session["txtFirstName"] = txtFirstName.Text;
        Session["txtLastName"] = txtLastName.Text;
        Session["txtPayRate"] = txtPayRate.Text;
        Session["txtStartDate"] = txtStartDate.Text;
        Session["txtEndDate"] = txtEndDate.Text;

        Response.Redirect("frmPersonnelVerified.aspx");
    }   

  }
}

如果我将所有字段留空，我会以连续的行显示所有错误消息并将其包装到下一行。我希望每个错误都有它自己的行。提前致谢！

Answer 1

在这种情况下，您最好的选择是StringBuilder来构建错误消息，最后在标签中显示错误。你可以通过以下方式实现这一目标：

 StringBuilder ErrorBuilder = new StringBuilder();
 ErrorBuilder.Append("Following are errors :");
        if (txtFirstName.Text.Trim() == "")
        {
            txtFieldError = true;
            ErrorBuilder.AppendLine("Must enter first name");
            txtFirstName.BackColor = System.Drawing.Color.Yellow;
        }

        if (txtLastName.Text.Trim() == "")
        {
            txtFieldError = true;
            ErrorBuilder.AppendLine("Must enter Last name");
            txtLastName.BackColor = System.Drawing.Color.Yellow;
        }

        // Rest of conditions here 

        lblError.Text = ErrorBuilder.ToString();

在我们使用+=时，为了best option is stringBuilder而不是ErrorBuilder.AppendLine连接字符串，newLine字符会自动附加字符串。

Answer 2

您应该能够将HTML放在那里，例如：

lblError.Text = lblError.Text + "<br> Must enter end date";

新行在多个if语句中使用的单个标签

2 个答案: