title: Why does "rails generate migration" call "invoke activerecord"
body: <p>When running:</p>
  
  <pre><code> rails generate migration &lt;someaction&gt; field:type
  </code></pre>
  
  <p>I can see it is performing two actions:</p>
  
  <ol>
  <li>Call invoke active_record</li>
  <li>Create a migration file.</li>
  </ol>
  
  <p>I understand perfectly why it is generating the migration file, but why does it invoke ActiveRecord? This bothers me because what if I want to create the migration file manually? how would I mimic this invocation (if it's even necessary..)?</p>