ES 2.0: excluding from source, but storing attachment, then retrieve via 'fields'

In ES 1.5 I was able to exclude an attachment from _source, but store it, so that the encoded text would not be stored, but the plain text would be. I could then access the text via 'fields' when running a query, i.e.
MyModel.search(query: { query_string: { query: "search text" } }, fields: ['_source', 'my_attachment']).

Now, in ES 2.0, I don't see any fields hash in the response. And I don't see the attachment text.

Is what I was doing still possible somehow with ES 2.0?