struts 2 checkboxlist validation question - validation

Question

I have struts 2 checkboxlist as followed:
<s:checkboxlist list="listOfOptions" name="someName" />
I would like to add validation to make sure that at least ONE of the checkboxes has been checked. Any thoughts?
Thanks

Answer 1

I use JS to do that.
<sx:submit
id="button_submit"
name="button_submit"
onclick="return validateNotEmptyCheckbox();" />
And JS:
function validateNotEmptyCheckbox() {
var checkboxes = document.getElementsByTagName('input');
for (i = 0; i < arguments.length; i++) {
var fieldName = arguments[i];
var atLeastOne = false;
for (j = 0; j < checkboxes.length; j++) {
if ((checkboxes[j].type == "checkbox" || checkboxes[j].type == "radio")
&& checkboxes[j].name == fieldName
&& checkboxes[j].checked == true)
atLeastOne = true;
}
if (atLeastOne == false) {
alert("Choose one!!!");
return false;
}
}
}
Also for radio buttons, as you can see.

Answer 2

I made an validation method on the action to whom the form is submitted.
deliveryTimesInputList is here the list of integer with the values from the checkboxlist.
#Override
public void validate() {
if(deliveryTimesInputList == null || deliveryTimesInputList.isEmpty()){
addFieldError("deliveryTimesInputList", "Du må velge minst et leveringstidspunkt for dette postnummeret");
}
}

Answer 3

Use the following code for struts2 xml validation .The value of checkbox List is stored as a string.Hence,you can use requiredstring.
<field name="someName">
<field-validator type="requiredstring">
<message>You need to select at least one option</message>
</field-validator>
</field>