title: knockoutjs data bind of something doesn't exist yet
body: <p>Lets say I have a list of items, and the data is created by mapping plugin, and it's normal that the list is empty. I would like to have a form that performs edit and create actions, which should bind to a single selected item.</p>
  
  <pre><code>&lt;div id="appointment-modal" class="reveal-modal" data-bind="with: appointment"&gt;
      &lt;form id="appointment-form" data-bind="submit: submit_appointment"&gt;
          &lt;input type="text" name="name" data-bind="value: name"/&gt;
          &lt;textarea name="description" data-bind="value: description"&gt;&lt;/textarea&gt;
          &lt;input type="text" name="time" data-bind="value time" /&gt;
          &lt;input type="text" name="address1" data-bind="value: address1"/&gt;
          &lt;input type="text" name="address2" data-bind="value: address2"/&gt;
          &lt;input type="text" name="phone" data-bind="value: phone"/&gt;
          &lt;input type="text" name="email" data-bind="value: email"/&gt;
      &lt;/form&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>The problem is, I get errors complaining about appointment is not defined:</p>
  
  <pre><code>Uncaught ReferenceError: Unable to parse bindings.
  Bindings value: with: appointment
  Message: appointment is not defined
  </code></pre>
  
  <p>I might be able to use the "if" binding to check if <code>appointment</code> exists, but I don't know how to cater for creation, ideally I would like to reuse the same form.</p>
  
  <p>Came across this <a href="http://knockoutjs.com/examples/betterList.html" rel="nofollow">link</a>, I can just create a dummy obervable "appointment", but since appointment is dummy, the div renders nothing, this is not good particularly for creating new appointment item.</p>