import pymongo

client = pymongo.MongoClient('0.0.0.0', 27017)
db = client.documents
collection = db.collections
test_data = collection.find_one({'metadata.encodingStage.terms.data.line.data.account.shortDescription': {'$exists': True}},
{'metadata.encodingStage.terms.data.line.data.account.shortDescription': 1})

{'_id': ObjectId('5a2fb9371de46756df51f37b'),
 'metadata': {'encodingStage': {'terms': {'data':
    {'line': [{'data': {'account': {'shortDescription': ['123456']}}},
              {'data': {'account': {'shortDescription': ['7890123']}}}]}}}}}

_id    shortDescription
-------------------------------------------------------
ObjectId('5a2fb9371de46756df51f37b')            123456
ObjectId('5a2fb9371de46756df51f37b')           7890123