title: Dynamo DB + In put Item Request how to pass null value?
body: <p>I have one field which i have declared as string in the model as show below:</p>
  
  <pre><code>App.Student= DS.Model.extend({
  name: DS.attr('string'),
  address1: DS.attr('string'),
  address2: DS.attr('string'),
  city: DS.attr('string'),
  state: DS.attr('string'),
  postal: DS.attr('string'),
  country: DS.attr('string'),
  });
  </code></pre>
  
  <p>Here in the Edit mode when i update Adderess 2 field as null then below error comes:     </p>
  
  <p><code>"Failed to edit property: One or more parameter values were invalid: An AttributeValue may not contain an empty string"</code> </p>
  
  <p>I know this Error is generated because i am updating address 2 field as null and that what i want <strong>Address 2 field is not mandatory(One can pass data or can also left that column as blank")</strong></p>