Mongodb $ always returns 0

Question

I have a database collection (called fols), for example:

{'followers':
        {
           '123':1
           '123':2
           '123':3
         }
}

If I run the query (using pymongo):

cursor = fols.find()
cursor.count()
>>3

It works great. Now:

cursor = fols.find({'followers':{'123':1}})
cursor.count()
>>1

Again works fine. BUT if I try:

cursor = fols.find({'followers':{'123':{'$exists': True}}})
cursor.count()
>> 0

It returns 0, although there are 3 records.

+5

Amitash Sep 13 '12 at 2:27

2 answers

Try the point syntax:

cursor = fols.find({'followers.123': {'$exists': True}})

But also see my comment above. You cannot have the same key more than once in a (sub) document.

+5

Thomas Sep 13 '12 at 2:44

Johnnyhk · Accepted Answer · 2012-09-13T02:43:25+0000

If you do not match the complete object, you need to use dot notation to use the operator against the inline object. So in this case:

cursor = fols.find({'followers.123':{'$exists': True}})