Find Unchecked Checkboxes with jQuery and pass the Names to C# Code

Question

This is my code:

public class MyCollection {
        internal static Dictionary<string, CheckBox> MyCheckBox = new Dictionary<string, CheckBox>();
    }


    protected void Page_Load(object sender, EventArgs e) {

        if (!IsPostBack) {
            CheckBox chk1 = new CheckBox();
            chk1.ID = "chk1";
            chk1.Checked = true;
            if (!MyCollection.MyCheckBox.ContainsKey(chk1.ID))
                MyCollection.MyCheckBox.Add(chk1.ID, chk1);

            CheckBox chk2 = new CheckBox();
            chk2.ID = "chk2";
            chk2.Checked = true;
            if (!MyCollection.MyCheckBox.ContainsKey(chk2.ID))
                MyCollection.MyCheckBox.Add(chk2.ID, chk2);

            pl1.Controls.Add(chk1);
            pl2.Controls.Add(chk2);
        }
    }

    protected void btn1Click(object sender, EventArgs e) {
        lit1.Text = "Chk1.Checked: " + MyCollection.MyCheckBox["chk1"].Checked.ToString();
        lit1.Text += "<br />Chk2.Checked: " + MyCollection.MyCheckBox["chk2"].Checked.ToString();
    }

i have 2 checkboxes, but always when press the button, Checkboxes.Checked are true, also when i unchecked them, how can i hold checkboxes in some dictionary like above and check their Checked property in right way? actualy i do't want any event for change Checkboxes, I Think about a jQuery script, that when i press the button retrive me the name of checkboxes that unchecked i find a jQuery that can find the checkboxe names that unchecked but i don't know how can pass the names to the c# code?

my above code is just a sample and real project is a user control that dynamically define and render controls from a type, hmm the scenario is like this: the clients add the assembly of user control and declare a property of that named target type, user control read target and for each property decide which control must be add so by overrided RenderContents and other methods can add controls to page, so every control automatically have a Checkbox that enable/disable control and i need the checked property

i find this code in Stackoverflow...

var sList = "";
$('input[type=checkbox]').each(function () {
var sThisVal = (this.checked ? "1" : "0");
sList += (sList=="" ? sThisVal : "," + sThisVal);
});
console.log (sList);

but this code just write sList on console how can retrive the sList values in C# Code?

I find it here: [Retrive values from jQuery to C# Code][1] [1]: http://stackoverflow.com/questions/7951202/retrive-values-from-jquery-to-c-sharp-code — Saeid, Oct 31 '11 at 08:49

Steve Rowbotham · Answer 1 · 2011-10-31T10:53:41.370

Firstly, you should never store an instance of a control such as a CheckBox in a static member since this is a recipe for a memory leak in your application. ASP.NET Control classes hold a reference to their containing Page and so by adding the Control to a static collection you're going to keep the entire Page instance and all its child Controls from being garbage-collected.

Secondly, there's no point in doing this in your case since it isn't going to achieve what you're trying to do. The instance of the CheckBox class that you add to the Dictionary isn't going to be the same instance that you want to interact with on subsequent requests; the instance you store in the Dictionary is for that request only which is why the CheckBox instances are always returning true from their Checked property.

I don't think that JQuery is relevant here since that will not help you reconstitute the CheckBox controls on the server. What you need to do is add the CheckBox controls to the Page on every request. In order for the CheckBox controls to have their state loaded from the Form collection you need to add the Controls early enough in the Page lifecycle: I would recommend trying to add them during the Page.Init event.

public void Page_Init(object sender, EventArgs e)
{
   CheckBox chk1 = new CheckBox();
   chk1.ID = "Chk1";

   CheckBox chk2 = new CheckBox();
   ck2.ID = "Chk2";

   if(!IsPostBack)
   {
      ck1.Checked = true;
      ck2.Checked = true;
   }

   p1.Controls.Add(chk1);
   p2.Controls.Add(chk2);
}

Without the actual code it is difficult to understand what you're trying to do and how you're going about it. The fact remains, though, that if you don't add the CheckBox controls to the Page on every request then they cannot participate in the Page lifecycle and won't have their state loaded from the Form collection when the Page is submitted. It sounds to me like you want to manipulate the control tree of the Page on the server but that needs to be reconstituted on every request and only exists during the handling of the request. After the Page is rendered to the client the control tree no longer exists.

So, you could POST the values of the HTML input checkboxes to the server using JavaScript but where would you send them and what do you expect to happen? It seems like you're fighting against the ASP.NET Webforms way of doing things which revolves around post-backs and the Page object on the server that handles the request.

Thanks about static members, but actually I think I can not add controls in page because my above code is just a sample and real project is a user control that dynamically define and render controls from a type, hmm the scenario is like this: the clients add the assembly of user control and declare a property of that named target type, user control read target and for each property decide which control must be add so by overrided RenderContents and other methods can add controls to page, so every control automatically have a Checkbox that enable/disable control and i need the checked property — Saeid, Oct 31 '11 at 04:58
I've expanded my answer, Saeid, but to be honest I think that you're perhaps misunderstanding how ASP.NET Web Forms works. — Steve Rowbotham, Oct 31 '11 at 10:57
Steve, thanks, I understand your expanding, and I don't want to manipulate control tree, that's solve it to me, thanks again. — Saeid, Oct 31 '11 at 14:25

score 1 · Answer 2 · answered Oct 30 '11 at 14:13

1

Remember please some simple thing: YOU MUST ADD DYNAMIC CONTROLS ON EACH AND EVERY POSTBACK. This will save a lot of your time.

answered Oct 30 '11 at 14:13

Yuriy Rozhovetskiy

22,270
4
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score 1 · Accepted Answer · edited May 23 '17 at 11:55

1

Use this one maybe useful this is all of your needed test it and let me know about the result:

Loop through checkboxes and count each one checked or unchecked

edited May 23 '17 at 11:55

Community

1
1

answered Nov 21 '11 at 11:16

Find Unchecked Checkboxes with jQuery and pass the Names to C# Code

3 Answers3