title: ActiveAdmin, datetime & Strong Parameters
body: <p>I have a model called 'Trainers' with a datetime field called <code>scheduled_interview</code> which is editable in ActiveAdmin:</p>
  
  <p><code>f.input :scheduled_interview</code></p>
  
  <p>This creates 5 <code>&lt;select&gt;</code>s (for year, month, day, hours &amp; mins).</p>
  
  <p>I've tried adding each of:</p>
  
  <p><code>permit_params :scheduled_interview =&gt; []</code></p>
  
  <p>and:</p>
  
  <p><code>permit_params scheduled_interview: []</code></p>
  
  <p>into <code>ActiveAdmin.register Trainer do ...</code> </p>
  
  <p>But when submitting the form, I see:</p>
  
  <p><code>Unpermitted parameters: scheduled_interview(1i), scheduled_interview(2i), scheduled_interview(3i), scheduled_interview(4i), scheduled_interview(5i)</code></p>
  
  <p>What am I doing wrong with the strong parameters?</p>
  
  <p><strong>Edit 1:</strong> this is using Rails 4, which I wasn't clear about.</p>
  
  <p><strong>Edit 2:</strong></p>
  
  <p>In the trainer controller:</p>
  
  <pre><code>def create
    @trainer = Trainer.new(application_params)
  end
  
  def application_params
    params.require(:trainer).permit(
      :name, :email, :scheduled_interview: []
    )
  end
  </code></pre>
  
  <p>Using just <code>:scheduled_interview</code> generates the same error as above.</p>
  
  <p><strong>Edit 3:</strong></p>
  
  <p>Log when saving trainer:</p>
  
  <pre><code>Started PATCH "/admin/prospective_trainers/trainer-id" for 10.0.2.2 at 2014-07-06 17:49:36 +0000
  Processing by Admin::ProspectiveTrainersController#update as HTML
    Parameters: {"utf8"=&gt;"✓", "prospective_trainers"=&gt;{"name"=&gt;"trainer name", "email"=&gt;"email@emailaddres.com", "scheduled_interview(1i)"=&gt;"2014", "scheduled_interview(2i)"=&gt;"7", "scheduled_interview(3i)"=&gt;"15", "scheduled_interview(4i)"=&gt;"16", "scheduled_interview(5i)"=&gt;"15"}, "commit"=&gt;"Update Trainer", "id"=&gt;"trainer-id"}
    AdminUser Load (1.2ms)  SELECT "admin_users".* FROM "admin_users" WHERE "admin_users"."id" = 8 ORDER BY "admin_users"."id" ASC LIMIT 1
    Trainer Load (1.2ms)  SELECT "trainers".* FROM "trainers" WHERE "trainers"."slug" = 'trainer-id' ORDER BY "trainers"."id" ASC LIMIT 1
  Unpermitted parameters: scheduled_interview(1i), scheduled_interview(2i), scheduled_interview(3i), scheduled_interview(4i), scheduled_interview(5i)
  Unpermitted parameters: utf8, _method, commit, id
     (0.4ms)  BEGIN
     (0.4ms)  COMMIT
  Redirected to http://localhost:3000/admin/prospective_trainers/trainer-id
    Trainer Load (1.0ms)  SELECT "trainers".* FROM "trainers" WHERE "trainers"."id" = $1 LIMIT 1  [["id", 327]]
  Completed 302 Found in 167ms (ActiveRecord: 4.3ms)
  </code></pre>
  
  <p>All other fields save just fine (name, email etc).</p>