How to I check if at least one checkbox is checked?

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Hi, Im trying to bind my data into gridview only when at least one checkbox is checked in each checkboxlist. However it does not seem to work as when I click on submit it with no checkbox checked it still go in the bind statement and did not display the text message in the label.

Where did it gone wrong in my code? please help

C#

if (IsPostBack)
                   {
                       if (!stringIsNullOrEmpty(CheckBoxList1.SelectedValue) && !stringIsNullOrEmpty(CheckBoxList2.SelectedValue) )
                       {
                           Bind();
                       }
                       else if (CheckBoxList1.SelectedValue == String.Empty)
                       {
                           LABEL1.Text = ("Please select at least one checkbox").ToString();
                       }
 
                       else if (CheckBoxList2.SelectedValue == String.Empty)
                       {
                           LABEL2.Text = ("Please select at least one checkbox").ToString();
                       }

Posted 26-Sep-15 17:22pm

waynetan123

Updated 26-Sep-15 19:25pm

v2

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Patrice T · Answer 1 · 2015-09-26T17:58:00

Solution 1

Simple, if your code always Bind, it is simply because CheckBoxList1.SelectedValue do not return null whether a box is checked or not.

Use a debugger and look at the value and type returned by CheckBoxList1.SelectedValue.

~~I wonder of this code compile ?~~ updated code must compile now.

I see that later, you compare CheckBoxList1.SelectedValue against String.Empty, if it work in second test, it should also work in first test.

I suggest to read the documentation to know the type returned by CheckBoxList1.SelectedValue

Posted 26-Sep-15 17:58pm

Patrice T

Updated 26-Sep-15 19:49pm

v3

Comments

waynetan123 27-Sep-15 0:09am

In debug !=null is true even when I did not check any item. please suggest alternative thanks

Patrice T 27-Sep-15 0:17am

see answer update

waynetan123 27-Sep-15 0:32am

still cant

Patrice T 27-Sep-15 0:43am

and what is saying the documentation ?

waynetan123 27-Sep-15 0:49am

what documentation are you referring to?

Patrice T 27-Sep-15 0:53am

You are using a function of a language, so there is documentation somewhere.

Patrice T 27-Sep-15 0:55am

May be you can use the debugger to see what value and type is returned by SelectedValue in both cases.

waynetan123 27-Sep-15 1:25am

Hi I updated my codes but still does not work. please help to see my updated codes thanks