title: How do I Unmarshal the bson from mongo of a nested interface with mgo?
body: <p>I have a collection of documents that contain an array of a custom interface type that I have. Example below. What do I need to do to Unmarshal the bson from mongo so I can eventually return a JSON response?</p>
  
  <pre><code>type Document struct {
    Props here....
    NestedDocuments customInterface
  }
  </code></pre>
  
  <p>What do I need to do to map the nested interfaces to the right structs?</p>