Python Driver

Connect to MongoDB using pymongo

from pymongo import MongoClient

uri = "mongodb://localhost:27017/"

client = MongoClient(uri)

db = client['test_db']
# or
# db = client.test_db

# collection = db['test_collection']
# or
collection = db.test_collection


collection.save({"hello":"world"})

print collection.find_one()

PyMongo queries

Once you got a collection object, queries use the same syntax as in the mongo shell. Some slight differences are:

every key must be enclosed in brackets. For example:

db.find({frequencies: {$exists: true}})

becomes in pymongo (note the True in uppercase):

db.find({"frequencies": { "$exists": True }})

objects such as object ids or `ISODate` are manipulated using python classes. PyMongo uses its own [`ObjectId`](http://api.mongodb.com/python/current/api/bson/objectid.html) class to deal with object ids, while dates use the standard `datetime` package. For example, if you want to query all events between 2010 and 2011, you can do:

 from datetime import datetime

 date_from = datetime(2010, 1, 1)
 date_to = datetime(2011, 1, 1)
 db.find({ "date": { "$gte": date_from, "$lt": date_to } }):

Update all documents in a collection using PyMongo

Let’s say you need to add a field to every document in a collection.

import pymongo

client = pymongo.MongoClient('localhost', 27017)
db = client.mydb.mycollection

for doc in db.find():
   db.update(
       {'_id': doc['_id']},
       {'$set': {'newField': 10} }, upsert=False, multi=False)

The find method returns a Cursor, on which you can easily iterate over using the for in syntax. Then, we call the update method, specifying the _id and that we add a field ($set). The parameters upsert and multi come from mongodb (see here for more info).

Syntax

• mongodb://[username:password@]host1[:port1][,host2[:port2],…[,hostN[:portN]]][/[database][?options]]

Parameters

|Parameter|Detail |---|---|---|---|---|---|---|---|---|--- |hostX|Optional. You can specify as many hosts as necessary. You would specify multiple hosts, for example, for connections to replica sets. |:portX|Optional. The default value is :27017 if not specified. |database|Optional. The name of the database to authenticate if the connection string includes authentication credentialsIf /database is not specified and the connection string includes credentials, the driver will authenticate to the admin database. |?options|Connection specific options