How to make a Bootstrap dropdown required?

Question

So, I've got following code for a dropdown box made with bootstrap:

<div class="btn-group">     <button id="landKapitein" type="button" data-toggle="dropdown" class="btn btn-default dropdown-toggle">Land         <span class="caret"></span>     </button>     <ul class="dropdown-menu">         <li><a role="menuitem" tabindex="-1" href="#">België/Belgique</a></li>         <li><a role="menuitem" tabindex="-1" href="#">Deutschland</a></li>         <li><a role="menuitem" tabindex="-1" href="#">France</a></li>         <li><a role="menuitem" tabindex="-1" href="#">Nederland</a></li>         <li><a role="menuitem" tabindex="-1" href="#">United Kingdom</a></li>      </ul> </div> 

Now I want to make it required to select something from this dropdown box before you can continue on. I've already done this for textboxes and radio buttons by just adding required to the tag, but I don't have a tag like that here, so how do I do this then?

Answer 1

If we just put required in select tag and <option value="">None</option> in the option it will work for validation. I have refer this page.

It works for selection must be made among provided value.

But I would like to know how to write custom validation message coming by default like this message.?

 <form action="demo_form.asp">     <select required>       <option value="">None</option>       <option value="volvo">Volvo</option>       <option value="saab">Saab</option>       <option value="mercedes">Mercedes</option>       <option value="audi">Audi</option>     </select>     <input type="submit">     </form> 

Above code works fine for validation like "Selecting an item in the list before submit".