MongoDB Queries cont

The sample DB for this post :

import pymongo
from datetime import *
client = pymongo.MongoClient("localhost", 27017)
#Create of get the DB 
db = client['test-database']

#create user collection

userCollection = db['userCollection']

for nextNo in range (1,10,2):
   new_user = {"Name":"zvika",
                "Age":42,
                "Childs":["Lior","Gal","Shahf"],
                "dateofbirth" : datetime(1970, 10, 25),
                "email" : "loveme42@hotmail.com",
                "RunningNo":nextNo ,
                "Blog address":"http://zvikastechnologiesblog.blogspot.com"}
   userCollection.save (new_user)

Limiting the returned fields from mondo db results :
Return only the age and email fields :

users = db.userCollection.find({"Name":"zvika"},{"Age":1,"email":2})
for user in users:
    print ( type ( user))
    print (  user)

returns:

<class 'dict'>
{'_id': ObjectId('519ddd10def1c122d4074eef'), 'email': 'loveme42@hotmail.com', 'Age': 42}

Add sorting users = db.userCollection.find({"Name":"zvika"},{"RunningNo":1,"email":2},sort=[("RunningNo", pymongo.DESCENDING)])

Limiting the resutls setusers = db.userCollection.find({"Name":"zvika"},{"RunningNo":1,"email":2},sort=[("RunningNo", pymongo.DESCENDING)]).limit(1)
Note:the result set limitation in this case is relevant to the sorted field in this case if there is a several documents with the same sorted value than all of them will return.

for an example after running the sample data five times the result of the query will be :
<class 'dict'>
{'email': 'loveme42@hotmail.com', '_id': ObjectId('519de196def1c115a050470f'), 'RunningNo': 9}
<class 'dict'>
{'email': 'loveme42@hotmail.com', '_id': ObjectId('519de196def1c115a050470f'), 'RunningNo': 9}
<class 'dict'>
{'email': 'loveme42@hotmail.com', '_id': ObjectId('519de196def1c115a050470f'), 'RunningNo': 9}
<class 'dict'>
{'email': 'loveme42@hotmail.com', '_id': ObjectId('519de196def1c115a050470f'), 'RunningNo': 9}
<class 'dict'>
{'email': 'loveme42@hotmail.com', '_id': ObjectId('519de196def1c115a050470f'), 'RunningNo': 9}
The same result will be applied to limit 1..5 only if the limit will be greater then 6 the next batch will be returned.

The limit parse could be write although in the following syntex:

users = db.userCollection.find({"Name":"zvika"},{"RunningNo":1,"email":2},sort=[("RunningNo", pymongo.DESCENDING)] ,limit=24)