MongoDB/PyMongo: BadValue Unsupported projection option when trying to query all dates after

Question

I've build a Twitter scraper that stores tweets into MongoDB. Now I'm trying to query the data with PyMongo.

Stored data in my MongoDB:

{
    "_id": {
        "$oid": "5555dc0e50f808afe0da52fe"
    },
    "text": "Lorem Ipsum...",
    "created_at": {
        "$date": "2015-05-15T10:55:16.000Z"
    },
}

Following works perfectly fine (but fetches every tweet ever tweeted):

dikt1 = {}
tweets_iterator = coll.find({},{ "text": 1, "user.screen_name":1 ,created_at': 1} )

for tweet in tweets_iterator:
        dikt1[tweet['text']] = tweet['created_at']

However when trying to query all dates after certain dates like this:

date1 = datetime.utcnow()-timedelta(days=30)
dikt1 = {}
tweets_iterator = coll.find({},{ "text": 1, "user.screen_name":1 , 'created_at': {'$gt': date1}} )
for tweet in tweets_iterator:
        dikt1[tweet['text']] = tweet['created_at']

The last line "for tweet in tweets_iterator:" gives an error:

OperationFailure: database error: Can't canonicalize query: BadValue Unsupported projection option: created_at: { $gt: new Date(1434480147418) }

Any advices?

Thanks!

Solution

If you want to apply a filter, use the first positional argument to find():

tweets_iterator = coll.find({'created_at': {'$gt': date1}}, {"text": 1, "user.screen_name": 1, 'created_at': 1})