Question

Im using the Simple form gem to setup a form on my rails app. I have a list of checkboxes (about 20 options) and i want to limit the user to selecting only 3. How can i achieve this?

View:

<%= f.association :interests, :as => :check_boxes, :label => false %>

First part of the Rendered HTML

<div class="control-group check_boxes optional">
  <div class="controls">
    <label class="checkbox">
        <input class="check_boxes optional" id="user_interest_ids_1" name="user[interest_ids][] "      
         type="checkbox" value="1" />Adventure Sports</label>
   <label class="checkbox">
       <input class="check_boxes optional" id="user_interest_ids_2" name="user[interest_ids][]"  
       type="checkbox" value="2" />Arts and Crafts</label>

Answer 1

Probably would go with jQuery to deal with this :

$(":checkbox").click(function(){
  $length = $(":checkbox").length();
  if ( $length > 2 ) {
    $(":checkbox:checked").attr("disabled", true);
  } else {
    $(":checkbox").removeAttr("disabled");
  }
});