Question

我想以随机顺序从数据库中填充5个值的RadioButtonList。

所以我尝试将5个值存储在Session对象中，然后使用以下代码将值随机添加到RadioButtonList（rblQuestions）：

    Random ran = new Random();
    var numbers = Enumerable.Range(1, 5).OrderBy(i => ran.Next()).ToList();

    List<ListItem> ans = new List<ListItem>();
    ans.Add(new ListItem(Session["Value1"].ToString(), "y"));
    ans.Add(new ListItem(Session["Value2"].ToString(), "n"));
    ans.Add(new ListItem(Session["Value3"].ToString(), "n"));
    ans.Add(new ListItem(Session["Value4"].ToString(), "n"));
    ans.Add(new ListItem(Session["Value5"].ToString(), "n"));

    foreach (int num in numbers)
    {
        rblQuestions.Items.Add(ans[num - 1]);
    }

这很有效。但是，当我单击同一表单上的另一个按钮时，列表中的所选项目会随机更改。为什么这样，我怎么能避免这个？

[编辑以包含代码。]

<form id="form1" runat="server">
<div>
    <asp:Button ID="btnGetQuestion" runat="server" Text="Get Question" OnClick="btnGetQuestion_Click" />
    <asp:Label ID="lblQuestion" runat="server" Text=""></asp:Label>
    <asp:RadioButtonList ID="rblQuestions" runat="server"></asp:RadioButtonList>
    <asp:Button ID="btnCheck" runat="server" Text="Check Answer" OnClick="btnCheck_Click" />
    <asp:Label ID="lblAnswer" runat="server" Text=""></asp:Label>
    <asp:Label ID="lblError" runat="server" Text=""></asp:Label>
</div>
</form>

C＃：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using MySql.Data.MySqlClient;
using System.Configuration;

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

protected void btnGetQuestion_Click(object sender, EventArgs e)
{
    getRandomQuestion();
}

protected void btnCheck_Click(object sender, EventArgs e)
{

}

protected void getRandomQuestion()
{
    string connStr = ConfigurationManager.ConnectionStrings["myConnectionString"].ConnectionString;
    MySqlConnection conn = new MySqlConnection(connStr);
    MySqlDataReader reader;

    try
    {
        conn.Open();

        string cmdText = "SELECT * FROM questions ORDER BY RAND() LIMIT 1";
        MySqlCommand cmd = new MySqlCommand(cmdText, conn);

        reader = cmd.ExecuteReader();

        if (reader.Read())
        {
            lblQuestion.Text = reader["question"].ToString();
            Session["Answer1"] = reader["answer1"].ToString();
            Session["Answer2"] = reader["answer2"].ToString();
            Session["Answer3"] = reader["answer3"].ToString();
            Session["Answer4"] = reader["answer4"].ToString();
            Session["Answer5"] = reader["answer5"].ToString();
        }
        else
        {
            lblError.Text = "(no questions found)";
        }
        reader.Close();
    }
    catch
    {
        lblError.Text = "Database connection error - failed to insert record.";
    }
    finally
    {
        conn.Close();
    }

    Random ran = new Random();
    var numbers = Enumerable.Range(1, 5).OrderBy(i => ran.Next()).ToList();

    List<ListItem> ans = new List<ListItem>();
    ans.Add(new ListItem(Session["Answer1"].ToString(), "y"));
    ans.Add(new ListItem(Session["Answer2"].ToString(), "n"));
    ans.Add(new ListItem(Session["Answer3"].ToString(), "n"));
    ans.Add(new ListItem(Session["Answer4"].ToString(), "n"));
    ans.Add(new ListItem(Session["Answer5"].ToString(), "n"));

    foreach (int num in numbers)
    {
        rblQuestions.Items.Add(ans[num - 1]);
    }
}
}

在回发时维护选定的单选按钮项目

0 个答案: