title: How to ensure a rails f.check_box (not check_box_tag) is initially checked based on active record object attribute?
body: <p>Having a heck of a time with this; I'm convinced I'm just not getting something completely obvious as I can't imagine this being this difficult intentionally. Everything else works in my form, but upon initial display, the check boxes are not checked when they should be. Here's the relevant erb:</p>
  
  <pre><code>&lt;%= form_for :project, :url=&gt;{:controller=&gt;'projects', :action=&gt;'update_permissions', :id=&gt;@project.id} do |f| %&gt;
  &lt;fieldset&gt;
    &lt;% @project.contributors.each do |contributor| %&gt;
    &lt;%= f.fields_for "contributors[#{contributor.id}]" do |c| %&gt;
    &lt;ul id="PermissionsList" class="permissions-grid in-line clearfix full"&gt;
    &lt;li&gt;
  
     &lt;ul class = "clearfix permission-row"&gt;
      &lt;li class="first"&gt;
       &lt;%= c.check_box :is_active %&gt;&lt;label for="&lt;%= contributor.id %&gt;"&gt;&lt;%= contributor.user.whole_name %&gt;&lt;/label&gt;
  
      &lt;/li&gt;
      &lt;% @roles.each do |role| %&gt;
       &lt;li&gt;&lt;%= c.radio_button :role_id, role.id, :id=&gt;"#{contributor.id}-#{role.id}" %&gt;&lt;%= label "#{contributor.id}-#{role.id}", role.role_name %&gt;&lt;/li&gt;
      &lt;% end %&gt;
  
     &lt;/ul&gt;
     &lt;% end %&gt;
    &lt;/li&gt;
  
   &lt;/ul&gt;
   &lt;% end %&gt;
  &lt;/fieldset&gt;
  </code></pre>
  
  <p>I'm passing the is_checked attribute (for the current contributor) to the check_box helper. This is the proper way to do this correct? Here's what the generated markup looks like:</p>
  
  <pre><code>&lt;ul class="clearfix permission-row"&gt;
      &lt;li class="first"&gt;
       &lt;input type="hidden" value="0" name="project[contributors[9]][is_active]"&gt;&lt;input type="checkbox" value="1" name="project[contributors[9]][is_active]" id="project_contributors_9__is_active"&gt;&lt;label for="9"&gt;Bill Hatch&lt;/label&gt;
  
      &lt;/li&gt;
       &lt;li&gt;&lt;input type="radio" value="1" name="project[contributors[9]][role_id]" id="9-1" style="display: none;"&gt;&lt;label for="9-1_Reviewer" style="display: none;"&gt;Reviewer&lt;/label&gt;&lt;/li&gt;
       &lt;li&gt;&lt;input type="radio" value="2" name="project[contributors[9]][role_id]" id="9-2" style="display: none;"&gt;&lt;label for="9-2_Tech. Reviewer" style="display: none;"&gt;Tech. reviewer&lt;/label&gt;&lt;/li&gt;
       &lt;li&gt;&lt;input type="radio" value="3" name="project[contributors[9]][role_id]" id="9-3" style="display: none;"&gt;&lt;label for="9-3_Contributor" style="display: none;"&gt;Contributor&lt;/label&gt;&lt;/li&gt;
  
     &lt;/ul&gt;
  </code></pre>
  
  <p>The value of the checkbox is 1, as it should be, so I'm a little confused as to why it's not displaying as checked. Like I said, I'm sure I'm just missing something obvious; no way can this be this hard;-)</p>