title: Rails: id field is nil when calling Model.new
body: <p>I am a little confused about the auto-increment id field in rails. I have a rails project with a simple schema. When i check the development.sqlite3 I can see that all of my tables have an id field with auto increment.</p>
  
  <pre><code>CREATE TABLE "messages" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "text" text, "created_at" datetime, "updated_at" datetime);
  </code></pre>
  
  <p>But when I call <code>Message.new</code> in the console, the resulting object has an <code>id</code> of <code>nil</code>.</p>
  
  <pre><code>&gt;&gt; a = Message.new
  =&gt; #&lt;Message id: nil, text: nil, created_at: nil, updated_at: nil&gt;
  </code></pre>
  
  <p>Shouldn't the <code>id</code> come back populated?</p>