title: ActiveAdmin how to display values in dropdown but store keys to db
body: <p>How can I display the string name, but save the integer key to the db in a dropdown in active admin?
  I have this form:</p>
  
  <pre><code>form do |f|
    f.inputs "Status" do
      f.input :status, as: :select, collection: App::STATUSES.keys
    end
    f.actions
  end
  </code></pre>
  
  <p>which produces this and works fine:
  <img src="https://i.stack.imgur.com/Ie8b8.png" alt="enter image description here"></p>
  
  <p>but I need it to produce this:
  <img src="https://i.stack.imgur.com/1oAsS.png" alt="enter image description here"></p>
  
  <p>This is the code which produces the above image. It displays the values that I want, but it doesn't save the keys (0, 1, 2, etc.) to the db</p>
  
  <pre><code>form do |f|
    f.inputs "Status" do
      f.input :status, as: :select, collection: App::STATUSES.values
    end
    f.actions
  end
  </code></pre>
  
  <p>I tried this but it doesn't work:</p>
  
  <pre><code>form do |f|
    f.inputs "Status" do
      f.input :status, as: :select, collection: App::STATUSES.values, :label_method =&gt; :status_name
    end
    f.actions
  end
  </code></pre>
  
  <p>Here is my model:</p>
  
  <pre><code>IN_PROGRESS = 0 #default
  SUBMITTED = 1
  REVIEW = 2
  PENDING = 3
  APPROVED = 4
  LIVE = 5
  
  
  STATUSES = {
    IN_PROGRESS =&gt; 'in progress',
    SUBMITTED =&gt; 'submitted',
    REVIEW =&gt; 'review',
    PENDING =&gt; 'pending',
    APPROVED =&gt; 'approved',
    LIVE =&gt; 'live'
  }
  
  def status_name
    STATUSES[status].to_s
  end
  </code></pre>
  
  <p>The status_name method works fine throughout my app, it just doesn't get called for some reason when displaying the dropdown.</p>