MongoDB-forespørgsel for kun at returnere indlejret dokument

Jeg tror, ​​det du ønskede, er dette:

print db.dvds.aggregate([
  {"$unwind": "$episodes"}, # One document per episode
  {"$match": {"episodes.title": "Episode 1"} }, # Selects (filters)
  {"$group": {"_id": "$_id", # Put documents together again
              "episodes": {"$push": "$episodes"},
              "title": {"$first": "$title"} # Just take any title
             }
  },
])["result"]

Outputtet (udover mellemrummene) er:

[ { u'episodes': [ { u'title': u'Episode 1',
                     u'desc': u'...'
                   }
                 ],
    u'_id': ObjectId('51542645a0c6dc4da77a65b6'),
    u'title': u'The Hitchhikers Guide to the Galaxy'
  }
]

Hvis du vil slippe af med u"_id" , tilføj pipelinen med:

  {"$project": {"_id": 0,
                "episodes": "$episodes",
                "title": "$title"}
               }