How to uncheck Checkbox without raising event

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I have a C# project wherein i have registered checkox event.When the checkbox is Unchecked i am displaying a message box which will prompt the user to confirm,if the user does not confirm then the checkbox should retain the state(Checked) So in code i try to check it which again raises the same event.
Is there a way to change the value without raising the event
I know this can be done by un-registering the event,set the value then re-register.but i am looking for a cleaner way. :doh:

Posted 18-Jan-10 22:01pm

krravisha

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alexey.nayda · Answer 1 · 2010-01-19T01:00:00

public class MyCheckEventArgs: EventArgs {
    public bool CurrentState { get; protected set; }
    public bool CancelEvent { get; set; }

    public MyCheckEventArgs(bool currentState) {
        CancelEvent = false;
        CurrentState = currentState;
    }
}

public class MyCheck : CheckBox {
    public EventHandler<MyCheckEventArgs> BeforeChecked;

    protected override void OnClick(EventArgs e) {
        bool handled = false;
        if (BeforeChecked != null) {
            MyCheckEventArgs myCheckEventArgs = new MyCheckEventArgs(this.Checked);
            BeforeChecked(this, myCheckEventArgs);
            handled = myCheckEventArgs.CancelEvent;
        }

        if (!handled)
            base.OnClick(e);
    }
}

I'm sure the rest you can do by yourself.

Regards,
Alexey

Christian Graus · Answer 2 · 2010-01-18T23:59:00

Solution 3

There are multiple reasons why the code someone else posted will not work.

if (UserChangedMind)
        CheckBox1.Checked = true;
    UserChangedMind = false;

is just one of them UserChangedMind is only ever true for a microsecond, as the second assignment always runs.

Posted 18-Jan-10 23:59pm

Christian Graus

#realJSOP · Answer 3 · 2010-01-20T00:22:00

Try it this way in your form class:

private bool initialized = false;

public MyForm()
{
    InitializeComponents();
    this.initialized = true;
}

void checkbox_clickevent(object sender, EventArgs e)
{
    // initialized prevents the message box from being displayed in the 
    // setting is loaded at startup that results in the checkbox being 
    // unchecked.
    if (initialized)
    {
        CheckBox checkBox = sender as CheckBox;
        // this will only ex3cute if the checkbox is unchecked by the user
        if (!checkBox.Checked)
        {
            if (!UserVerified())
            {
                checkBox.Checked = true;
            }
        }
    }
}

You may need to tweak this a bit, but I think you get the idea.

Sandeep Mewara · Answer 4 · 2010-01-19T00:10:00

You can achieve it easliy using Javascipt.

1. Add a onclick/onchange javascript event to the checkbox
2. In the event raised - handle the scenario
a. Checkbox unchecked - leave as it is procceed
b. Checkbox checked - prompt a 'confirm' box. Ask for confirmation. If Yes: return true and move on. such that the server onchange event is fired. Take appropriate action needed there.
If No: toggle the checkbox value back and return false, move on. Such that the server event is no more fired and the click/confirm was all on the client side.

Hope that helps

Christian Graus · Answer 5 · 2010-01-18T23:33:00

Solution 1

Well, you're asking for the event framework to break itself. No, you can't do that. Sadly, and it's not pretty, the only way I know of to do stuff like that, is to set some sort of flag that the event code knows to check, in order to ignore the event.

Posted 18-Jan-10 23:33pm

Christian Graus

How to uncheck Checkbox without raising event

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