Getting started with PyMongo

Hello, World

PyMongo is a native Python driver for MongoDB.

Install PyMongo

pip install pymongo

Create a connection

Use MongoClient to create a connection. MongoClient defaults to MongoDB instance running on localhost:27017 if not specified.

from pymongo import MongoClient
client = MongoClient() 

Access Database Objects

PyMongo’s Database class represents database construct in MongoDB. Databases hold groups of logically related collections.

db = client.mydb

Access Collection Objects

PyMongo’s Collection class represents collection construct in MongoDB. Collections hold groups of related documents.

col = db.mycollection

MongoDB creates new databases and collections implicitly upon first use.

Basic CRUD Operation

MongoDB stores data records as BSON documents. BSON is the binary representation of JSON.

$ python
>>> from pymongo import MongoClient
>>> client = MongoClient()
>>> col = client.mydb.test

Create

Insert a single document insert_one(document)

>>> result = col.insert_one({'x':1})
>>> result.inserted_id
ObjectId('583c16b9dc32d44b6e93cd9b')

Insert multiple documents insert_many(documents)

>>> result = col.insert_many([{'x': 2}, {'x': 3}])
>>> result.inserted_ids
[ObjectId('583c17e7dc32d44b6e93cd9c'), ObjectId('583c17e7dc32d44b6e93cd9d')]

Replace a single document matching the filter replace_one(filter, replacement, upsert=False). (to insert a new document if matching document doesn’t exist, use upsert=True)

>>> result = col.replace_one({'x': 1}, {'y': 1})
>>> result.matched_count
1
>>> result.modified_count
1

Update

Update a single document matching the filter update_one(filter, update, upsert=False)

>>> result = col.update_one({'x': 1}, {'x': 3})

Update one or more documents that match the filter update_many(filter, update, upsert=False)

>>> result = col.update_many({'x': 1}, {'x': 3})

Read

Query the database find(filter=None, projection=None, skip=0, limit=0, no_cursor_timeout=False). The filter argument is a prototype document that all results must match.

>>> result = col.find({'x': 1})

Get a single document from the database find_one(filter=None)

>>> result = col.find_one()

Query With Projection

query={'x':1}
projection={'_id':0, 'x':1} # show x but not show _id
result=col.find(query,projection)

Delete

Delete a single document matching the filter delete_one(filter)

>>> result = col.delete_one({'x': 1})
>>> result.deleted_count
1

Delete one or more documents matching the filter delete_many(filter)

>>> result = col.delete_many({'x': 1})
>>> result.deleted_count
3

PyMongo also provides find_one_and_delete(), find_one_and_update() and find_one_and_replace() functionality.

Installation or Setup

Detailed instructions on getting pymongo set up or installed.

  • Installing with Pip

    • To install pymongo for the first time:

      pip install pymongo

    • Installing a specific version of pymongo:

      Where X.X.X is the version to be installed

      pip install pymongo==X.X.X

    • Upgrading existing pymongo:

      pip install --upgrade pymongo

  • Installing with easy_install

    • To install pymongo for the first time:

      python -m easy_install pymongo

    • Upgrading existing pymongo:

      python -m easy_install -U pymongo