title: Filtering / Querying by the Contents of a List in DynamoDB
body: <p>I am attempting to filter a DynamoDB query by the contents of a Map contained within a List.  Here's an example of the structure I'm dealing with.</p>
  
  <pre><code>{
      'EventType': 'git/push'
      'EventTime': 1416251010,
      'Commits': [
          {
              'id': '29d02aff...',
              'subject': 'Add the thing to the place'
          },
          {
              'id': '9d888fec...',
              'subject': 'Spelling errors'
          },
          ...
      ]
  }
  </code></pre>
  
  <p>The hash key is <code>EventType</code> and range key <code>EventTime</code>.  I am trying to write a filter that filters the result of a query to a specific <code>id</code>.  Is is possible to create a DynamoDB filter expression that correctly filters the query like this?  (My first thought was to use <code>contains (a, a)</code>, but I don't think that will work on a List of Maps.)</p>