【问题标题】:why does checkchanged event does not fire on uncheck of checkbox in asp.net为什么在asp.net中未选中复选框时checkedchanged事件不会触发
【发布时间】:2013-03-24 06:01:22
【问题描述】:

考勤跟踪器应用程序的一部分,显示用户的主题并让他标记自己的考勤。

使用 enableviewstate="true",复选框不会被取消选中,并且 checkchanged 事件不会执行。

namespace portal

{

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

        String[] split; string day;
        protected void Page_Load(object sender, EventArgs e)
        {

            /* if (Session["uname"] == null)
             {
                 Response.Redirect("Firstpage.aspx");
             }*/
            String[] split = new String[16];
            DateTime d1 = DateTime.Today;
            string month = d1.ToString("MMMM");
            Lblmonth.Text = month;
            String userid = Session["uname"].ToString();
            SqlConnection con2 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
            SqlCommand cmd2 = new SqlCommand("select sbranch ,syear from studdetails where userid=@userid ", con2);
            cmd2.Parameters.AddWithValue("userid", userid);
            String branch = "", year = "";
            SqlDataReader rdr2 = null;
            con2.Open();
            rdr2 = cmd2.ExecuteReader();
            while (rdr2.Read())
            {
                branch = rdr2["sbranch"].ToString();
                year = rdr2["syear"].ToString();
            }
            con2.Close();
            int sem = 0;
            switch (year)
            {
                case "B.E": sem = 8;
                    break;
                case "T.E": sem = 6;
                    break;
                case "S.E": sem = 4;
                    break;
                case "F.E": sem = 2;
                    break;
                default: sem = 2;
                    break;

            }

            int tempmonth = (int)(d1.Month);
            if (tempmonth > 6)
                sem = sem - 1;



            SqlConnection con3 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
            SqlCommand cmd3 = new SqlCommand("select subject from subjecttable where department=@dept and semester=@sem ", con3);
            cmd3.Parameters.AddWithValue("dept", branch);
            cmd3.Parameters.AddWithValue("sem", sem);
            con3.Open();
            SqlDataReader rdr3 = null;
            rdr3 = cmd3.ExecuteReader();
            string subject = "";
            while (rdr3.Read())
            {
                subject = rdr3["subject"].ToString();

            }
            con3.Close();
            Char[] separator = new Char[] { ',' };
            String[] subsplit = subject.Split(separator);
            int size = subsplit.Length;
            switch (size)
            {
                case 6: subj6.Text = subsplit[5];
                    goto case 5;
                case 5: subj5.Text = subsplit[4];
                    goto case 4;
                case 4: subj4.Text = subsplit[3];
                    goto case 3;
                case 3: subj3.Text = subsplit[2];
                    goto case 2;
                case 2: subj2.Text = subsplit[1];
                    goto case 1;
                case 1: subj1.Text = subsplit[0];
                    break; ;

            }

        }
        protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)
        {
            if (e.Day.IsWeekend)
            {
                e.Cell.BackColor = System.Drawing.Color.DarkBlue;
            }
            else
            {
                e.Cell.BackColor = System.Drawing.Color.LightBlue;
            }
            SelectedDatesCollection dates = Calendar1.SelectedDates;

            DateTime toDay = DateTime.Today;
            string days = toDay.ToLongDateString();

            Labelday.Text = days;
            Char[] separator = new Char[] { ',' };
            String[] split1 = days.Split(separator);
            day = split1[0];
            Session["day"] = Calendar1.SelectedDate.ToShortDateString();
            if (dates.Count > 0)
            {
                Labelday.Text = dates[0].ToLongDateString() + "<br />";
                String temp = Labelday.Text;
                split1 = temp.Split(separator);
                day = split1[0];
            }
            if (!(day.Equals("Saturday") || day.Equals("Sunday")))
            {
                SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                string cla = Convert.ToString(Session["uclass"]);
                SqlCommand cmd = new SqlCommand("select " + day + " from studtimetable where class = @class ", con);

                con.Open();
                cmd.Parameters.AddWithValue("class", cla);
                SqlDataReader rdr = null;
                String tt = "";
                rdr = cmd.ExecuteReader();
                while (rdr.Read())
                {
                    tt = rdr[day].ToString();
                }
                con.Close();

                split = tt.Split(separator);
                int size = split.Length;
                lbltime.Visible = true;
                Lblsubj.Visible = true;
                Lblatt.Visible = true;
                switch (size)
                {
                    case 16: Label15.Text = split[15];
                        Session["l15"] = Label15.Text;
                        Label14.Text = split[14];
                        CheckBox8.Visible = true;

                        goto case 14;
                    case 14: Label13.Text = split[13];
                        Session["l13"] = Label13.Text;
                        Label12.Text = split[12];
                        CheckBox7.Visible = true;
                        goto case 12;
                    case 12: Label11.Text = split[11];
                        Session["l11"] = Label11.Text;
                        Label10.Text = split[10];
                        CheckBox6.Visible = true;
                        goto case 10;
                    case 10: Label9.Text = split[9];
                        Session["l9"] = Label9.Text;
                        Label8.Text = split[8];
                        CheckBox5.Visible = true;
                        goto case 8;
                    case 8: Label7.Text = split[7];
                        Session["l7"] = Label7.Text;
                        Label6.Text = split[6];
                        CheckBox4.Visible = true;
                        goto case 6;
                    case 6: Label5.Text = split[5];
                        Session["l5"] = Label5.Text;
                        Label4.Text = split[4];
                        CheckBox3.Visible = true;
                        goto case 4;
                    case 4: Label3.Text = split[3];
                        Session["l3"] = Label3.Text;
                        Label2.Text = split[2];
                        CheckBox2.Visible = true;
                        goto case 2;
                    case 2: Label1.Text = split[1];
                        Session["l1"] = Label1.Text;
                        Label0.Text = split[0];
                        CheckBox1.Visible = true;
                        break;

                }

            }
            else
            {
                lbltime.Text = "Enjoy weekend";
                lbltime.Visible = true;
            }
        }
        protected void Calendar1_SelectionChanged(object sender, EventArgs e)
        {

            CheckBox1.Checked = false;

            CheckBox2.Checked = false;

            CheckBox3.Checked = false;

            CheckBox4.Checked = false;

            CheckBox5.Checked = false;

            CheckBox6.Checked = false;

            CheckBox7.Checked = false;

            CheckBox8.Checked = false;
        }



        protected void CheckBox1_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox1.Checked == true)
            {
                string sub = Session["l1"].ToString();
                string userid = Session["uname"].ToString();
                string date = Session["day"].ToString();
                string tempclass = Session["uclass"].ToString();

                SqlConnection con4 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                SqlCommand cmd4 = new SqlCommand("insert into " + tempclass + "track values ('" + userid + "','" + sub + "','" + date + "')", con4);
                con4.Open();

                cmd4.ExecuteNonQuery();
                con4.Close();


            }
            else
            {
                Label18.Text = "uncheck";//temporary to check if this block executes
            }
        }



        protected void CheckBox2_CheckedChanged(object sender, EventArgs e)
        {

            if (CheckBox2.Checked == true)
            {
                string sub = Session["l3"].ToString();
                string userid = Session["uname"].ToString();
                string date = Session["day"].ToString();
                string tempclass = Session["uclass"].ToString();

                SqlConnection con4 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                SqlCommand cmd4 = new SqlCommand("insert into " + tempclass + "track values ('" + userid + "','" + sub + "','" + date + "')", con4);
                con4.Open();

                cmd4.ExecuteNonQuery();
                con4.Close();

                //Response.Redirect("tracker.aspx");
            }
            else
            {
            }

        }

        protected void CheckBox3_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox3.Checked == true)
            {
                string sub = Session["l5"].ToString();
                string userid = Session["uname"].ToString();
                string date = Session["day"].ToString();
                string tempclass = Session["uclass"].ToString();

                SqlConnection con4 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                SqlCommand cmd4 = new SqlCommand("insert into " + tempclass + "track values ('" + userid + "','" + sub + "','" + date + "')", con4);
                con4.Open();

                cmd4.ExecuteNonQuery();
                con4.Close();

                //Response.Redirect("tracker.aspx");
            }
            else
            {
            }

        }

        protected void CheckBox4_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox4.Checked == true)
            {
                string sub = Session["l7"].ToString();
                string userid = Session["uname"].ToString();
                string date = Session["day"].ToString();
                string tempclass = Session["uclass"].ToString();

                SqlConnection con4 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                SqlCommand cmd4 = new SqlCommand("insert into " + tempclass + "track values ('" + userid + "','" + sub + "','" + date + "')", con4);
                con4.Open();

                cmd4.ExecuteNonQuery();
                con4.Close();

                //Response.Redirect("tracker.aspx");
            }
            else
            {

            }

        }

        protected void CheckBox5_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox5.Checked == true)
            {
                string sub = Session["l9"].ToString();
                string userid = Session["uname"].ToString();
                string date = Session["day"].ToString();
                string tempclass = Session["uclass"].ToString();

                SqlConnection con4 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                SqlCommand cmd4 = new SqlCommand("insert into " + tempclass + "track values ('" + userid + "','" + sub + "','" + date + "')", con4);
                con4.Open();

                cmd4.ExecuteNonQuery();
                con4.Close();

                //Response.Redirect("tracker.aspx");
            }
            else
            {
            }
        }

        protected void CheckBox6_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox6.Checked == true)
            {
                string sub = Session["l11"].ToString();
                string userid = Session["uname"].ToString();
                string date = Session["day"].ToString();
                string tempclass = Session["uclass"].ToString();

                SqlConnection con4 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                SqlCommand cmd4 = new SqlCommand("insert into " + tempclass + "track values ('" + userid + "','" + sub + "','" + date + "')", con4);
                con4.Open();

                cmd4.ExecuteNonQuery();
                con4.Close();

                //Response.Redirect("tracker.aspx");
            }
            else
            {
            }
        }

        protected void CheckBox7_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox7.Checked == true)
            {
                string sub = Session["l13"].ToString();
                string userid = Session["uname"].ToString();
                string date = Session["day"].ToString();
                string tempclass = Session["uclass"].ToString();

                SqlConnection con4 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                SqlCommand cmd4 = new SqlCommand("insert into " + tempclass + "track values ('" + userid + "','" + sub + "','" + date + "')", con4);
                con4.Open();

                cmd4.ExecuteNonQuery();
                con4.Close();

                //Response.Redirect("tracker.aspx");
            }
            else
            {
            }

        }

        protected void CheckBox8_CheckedChanged(object sender, EventArgs e)
        {
            if (CheckBox8.Checked == true)
            {
                string sub = Session["l15"].ToString();
                string userid = Session["uname"].ToString();
                string date = Session["day"].ToString();
                string tempclass = Session["uclass"].ToString();

                SqlConnection con4 = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\mmm\portal\App_Data\student.mdf;Integrated Security=True;User Instance=True");
                SqlCommand cmd4 = new SqlCommand("insert into " + tempclass + "track values ('" + userid + "','" + sub + "','" + date + "')", con4);
                con4.Open();

                cmd4.ExecuteNonQuery();
                con4.Close();

                //Response.Redirect("tracker.aspx");
            }
            else
            {
            }
        }
    }
}

【问题讨论】:

  • 也许你应该检查 CheckBox State
  • 您如何通过Visible="False" 获得用户操作?
  • 老实人。忽略可见 = false..from 8 个复选框,我根据页面加载事件中的用户将可见 = true
  • 乍一看,您正在更改选中状态的唯一地方是 Calendar1_SelectionChanged - 仅出于测试目的,您为什么不注释掉该方法的主体,看看您是否仍然遇到同样的错误。
  • thnx loren 浏览了代码。我尝试评论但没有帮助。当用户取消选中 checkbox1 时,我担心为什么 checkchanged 事件的 else 部分没有被执行

标签: c# asp.net checkbox


【解决方案1】:

来自 MSDN (http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.checkbox.oncheckedchanged.aspx):

CheckBox 控件必须在发送到 服务器以使此事件正常工作。确保视图状态是 为此控件启用。

当 (html) 复选框未选中并提交表单时,不会将任何值传递回服务器,这就是您需要为此控件启用 ViewState 的原因,因此 ASP.NET 会跟踪状态(选中/未选中)。

【讨论】:

  • 当我设置启用 viewstate=true 时,它​​不允许我取消选中该复选框。在取消选中时,页面重新加载并且复选框保持选中状态。
  • 您可能在 ASP.NET 页面生命周期中还有其他内容,即在事件处理后设置复选框,或者您在事件中修改数据后没有从商店重新加载数据处理程序。
  • thnx floremin.. 但我正在重新加载数据...我猜由于 enableviewstate=true,复选框保留了以前的状态..
  • 这里有一些解决方案..但不理解..谁能详细说明...stackoverflow.com/questions/1404528/…
  • 然后你可以在CheckBox1_CheckedChanged处理程序中处理INSERT或DELETE后设置CheckBox1.Checked = false
【解决方案2】:

删除 EnableViewState="false" 应该可以正常工作

【讨论】:

  • 删除 EnableViewState="false" 无济于事..当我选中复选框时,它会被选中并正确执行..但是它不允许我取消选中复选框。当我尝试取消选中时,页面重新加载并且复选框保持选中状态。
  • 您是否从来自数据库的数据中选中此框?听起来您的代码隐藏文件中正在重新选中该框。
  • 我开始了一个空项目,对其进行了测试,并且每次都能完美运行,所以我认为您没有向我们展示的代码会影响复选框选中状态。
  • thnx loren.. 考虑到您的回答,即使我执行了一个新项目并且确实有效...请您仔细阅读我的整个代码并回答导致复选框的代码缺陷在哪里保持检查... PS:此代码是考勤跟踪器应用程序的一部分,它根据用户显示时间表并让他标记自己的考勤
  • 请浏览整个代码并告诉我哪个语句不允许取消选中复选框。同样在调试器模式下,取消选中时,checkchanged 根本不执行。
【解决方案3】:

感谢大家的考虑。 问题终于解决了。在用户取消选中事件时,checkchanged 方法没有执行,因为 1) 启用自动回发,取消选中导致 page_load 方法的执行,这反过来导致 checkbox.visible=false,所以 checkchanged 没有执行,然后日历渲染方法导致 checkbox.visible =true 与前一个状态(viewstate=true) 即检查状态。

特别感谢弗洛雷明和罗兰。

【讨论】:

  • 我遇到了同样的问题。在我的例子中,CheckBox 默认是禁用的(Enabled="false")。所以没有为控件加载 ViewState。
【解决方案4】:

解决方案:您应该设置-> EnableViewstate = True,ViewStateMode = Enabled,Autopostback = true。就这样。这对我有用。

【讨论】:

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