C#, ASP How to check how many check boxes are checked

Hello,
We have a web page with dynamically loaded check boxes (depends on how many records in database).
What i need is to make sure the user checks only 5 check boxes. And if he checks the 6th one, give him a message that he can only check 5.
ASP:
Please select up to five:
<asp:Repeater runat="server" ID="rptCandidats" >
        <ItemTemplate>
             <div>
                 <asp:checkbox id="chResponse" runat="server"  AutoPostBack="True"   OnCheckedChanged="Check_Clicked"></asp:checkbox>
<%# Eval("ResText")%> <a href="<%#Eval("ResLink")%>" class="moreinfo">   More Info</a>
                 <asp:HiddenField ID="ResId" runat="server" Value ='<%#Eval("ResponId")%>' />                           </div>
       </ItemTemplate>
</asp:Repeater>

Open in new window

I tried to use OnCheckedChanged event, but it doesn't work.
Below is a C# code:
protected void Check_Clicked(Object sender, EventArgs e)
       {
           int checkedCount = 0;
           foreach (RepeaterItem r in rptCandidats.Items)
           {
              CheckBox cb = (CheckBox)r.FindControl("chResponse");
               if (cb.Checked)
               {
                   checkedCount += (sender as CheckBox).Checked ? 1 : -1;
               }
           }
           if (checkedCount > 5)
           {
               System.Web.HttpContext.Current.Response.Write("<SCRIPT LANGUAGE=\"JavaScript\">alert(\"Only Up to five candidates can be selected.\")</SCRIPT>");
           }

       }

Open in new window

Any ideas how can i achieve it?
Thanks.
Galina BesselyanovaSenior Software Developer/EngineerAsked:
Who is Participating?

Improve company productivity with a Business Account.Sign Up

x
 
Scott Fell, EE MVEConnect With a Mentor Developer & EE ModeratorCommented:
I'm not a .NET dev.   An alternative would be to do this in javascript and avoid the call to the server.  You would still want to test serverside for more than 5 checks.  This is one way to do what I think you want on the front end.

A live sample http://jsbin.com/visiy/1/edit where I used the jquery docs as the base.  http://api.jquery.com/checked-selector/
<!DOCTYPE html>
<html>
<head>
<style>
  .error{background-color:pink;padding:5px;}
  </style>
<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
  <script>
    $(function() {
    var countChecked = function () {
    var n = $("input.chResponse:checked").length;
    if (n > 5) {
        $('#myButton').prop('disabled', true);
       
        $('div.msg').addClass('error').html('You have checked more than 5 boxes.  The submit button has been disabled.  Please check only 5 boxes');
    } else {
        $('#myButton').prop('disabled', false);
        $('div.msg').removeClass('error').html('Please check no more than 5 boxes');
    }
};
countChecked();

$("input[type=checkbox].chResponse").on("click", countChecked);
    });      
  </script>
</script>
  <meta charset="utf-8">
  <title>EE Q_28391393</title>
</head>
<body>
<input type="checkbox" class="chResponse">check1<br>
<input type="checkbox" class="chResponse">check2<br>
<input type="checkbox" class="chResponse">check3<br>
<input type="checkbox" class="chResponse">check4<br>
<input type="checkbox" class="chResponse">check5<br>
<input type="checkbox" class="chResponse">check6<br>
<input type="checkbox" class="chResponse">check7<br>
<input type="checkbox" class="chResponse">check8<br>
  <div class="msg">Please check no more than 5 boxes</div>
  <button id="myButton">Submit</button>
</body>
</html>

Open in new window

0
 
Kyle AbrahamsSenior .Net DeveloperCommented:
Don't use response.Write.

use ScriptManager.RegisterStartupScript:
http://msdn.microsoft.com/en-us/library/bb359558%28v=vs.110%29.aspx


 string javaScript = "<script language=JavaScript>\n" + "alert('Only Up to five candidates can be selected');\n" + "</script>";

ScriptManager.RegisterStartupScript(updatePanelId,updatePanelId.GetType()
                                                      , "alert", javaScript, true);
0
 
Galina BesselyanovaSenior Software Developer/EngineerAuthor Commented:
Thanks!
Here is my new code
 protected void Check_Clicked(Object sender, EventArgs e)
       {
           string sysAlert="Only up to five selections.";
           int checkedCount = 0;
           foreach (RepeaterItem r in rptCandidats.Items)
           {
               CheckBox cb = (CheckBox)r.FindControl("chResponse");
               if (cb.Checked)
               {
                   checkedCount += (sender as CheckBox).Checked ? 1 : -1;
                   if (checkedCount > 5)
                   {
                      
       Page.ClientScript.RegisterStartupScript(this.GetType(), "This Alert", "alert('" + sysAlert + "');", true);
       cb.Checked = false;

                   }
               }
           }
          
       }

Open in new window

It is working, but now, when you click on the check box, the page blinking like it reloads .
0
What Kind of Coding Program is Right for You?

There are many ways to learn to code these days. From coding bootcamps like Flatiron School to online courses to totally free beginner resources. The best way to learn to code depends on many factors, but the most important one is you. See what course is best for you.

 
Kyle AbrahamsSenior .Net DeveloperCommented:
take it out of the for each. and do you have your repeater ajaxified in an updatepanel?

protected void Check_Clicked(Object sender, EventArgs e)
       {
           string sysAlert="Only up to five selections.";
           int checkedCount = 0;
           foreach (RepeaterItem r in rptCandidats.Items)
           {
               CheckBox cb = (CheckBox)r.FindControl("chResponse");
               if (cb.Checked)
               {
                   checkedCount += cb.Checked ? 1 : 0;
                }
           }
          
        if (checkedCount > 5)
        {

       Page.ClientScript.RegisterStartupScript(this.GetType(), "This Alert", "alert('" + sysAlert + "');", true);
       cb.Checked = false;
        }

       } 

Open in new window

0
 
Galina BesselyanovaSenior Software Developer/EngineerAuthor Commented:
I'm sorry, i'm new to it.
There is no updatepanel.
And why remove For each if i need to count how many check boxes are already checked?
Am i doing something wrong?
0
 
Kyle AbrahamsSenior .Net DeveloperCommented:
@kqureshi321

If you see the code I modified I still use the for each, I just moved the register script out of it.  

http://www.experts-exchange.com/Programming/Languages/C_Sharp/Q_28391393.html#a39937803
0
 
Galina BesselyanovaSenior Software Developer/EngineerAuthor Commented:
Even with this change, the page still blinks like it reloads.
0
 
Kyle AbrahamsConnect With a Mentor Senior .Net DeveloperCommented:
that's coming from the postback.


add this to your front end:

<asp:UpdatePanel runat="server" id="UpdatePanel1">
<ContentTemplate >
  <! --- repeater goes in here -->
</ContentTemplate >
</UpdatePanel>

You can also take the javascript approach . . . but I've never been a fan of it for maintenance reasons.
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.