How to validate list box with jquery validate

Question

I'm using jquery validate and it works with the normal fields. I need a way to make sure there is at least one entry in the one listbox before validation is satisfied. I tried to add a custom method.

$.validator.addMethod('checklist', function(value, element) {
  if ($("#currentimp").val() ==""){
    return false;
    } else return true;
  }, "Listbox is empty");

Then in the rules i have the following:

currentimp: {
   checklist:true
}

I'm not sure if there is a better way to accomplish this but I haven't seen any good examples for what I'm trying to do. I also changed my form button to a submit button but it won't submit unless I add in a submit function to the submithandler. Is this normal?

Answer 1

如果列表框是某种选择框或单选框，则只需使用required:true规则，而无需创建自己的自定义规则。

Answer 2

Quote OP :

"I need a way to make sure there is at least one entry in the one listbox before validation is satisfied."

If by "listbox", you mean <select multiple="multiple"> , then you do not need to write a custom method; you'd use the required rule.

The trick with validating a select is that your first <option> must contain value="" .

HTML :

<select name="currentimp" id="currentimp" multiple="multiple">
    <option value="">...</option>
    <option value="1">option 1</option>
    <option value="2">option 2</option>
    <option value="3">option 3</option>
    <option value="4">option 4</option>
</select>

jQuery :

$(document).ready(function () {

    $('#myform').validate({
        rules: {
            currentimp: {
                required: true
            }
        }
    });

});

DEMO: http://jsfiddle.net/5GKbF/

---

Quote OP :

"I also changed my form button to a submit button but it won't submit unless I add in a submit function to the submithandler. Is this normal?"

No, this is not normal.

The jQuery Validate plugin will always capture the click of any button with type="submit" as long as it's contained within your <form></form> tags.

Both <input type="submit" ... and <button type="submit" ... are acceptable.

The submitHandler callback is not a mandatory option.

If you leave out the submitHandler callback option, upon successful validation, the form will submit to the URL specified within your action attribute.

<form action="myScript.php" ...

Typically, the submitHandler is only used when you want to bypass the action and submit the form via .ajax() , and/or perform some other function(s).