MongoDB insert & update demo.

mongodb_update_demo.py

"""
MongoDB insert & update demo.

Create a database & collection on a local MongoDB instance, and insert & update
some documents.

"""


import pymongo
from pprint import pprint


# -----------------------------------------------------------------------------
# *** Preparations

client = pymongo.MongoClient()

my_db = client.my_database

my_col = my_db['my_collection']


# -----------------------------------------------------------------------------
# *** Insert datapoints

observation_01 = {
    'name': 'Ron',
    'IQ': 82.2,
    'hair_colour': 'ginger',
    }
observation_02 = {
    'name': 'Hermione',
    'IQ': 178.5,
    'hair_colour': 'brown',
    }
response = my_col.insert_many([observation_01, observation_02])

query_result = list(my_col.find({}, {'_id': False}))
pprint(query_result)
# Returns:
# [{'IQ': 82.2, 'hair_colour': 'ginger', 'name': 'Ron'},
#  {'IQ': 178.5, 'hair_colour': 'brown', 'name': 'Hermione'}]


# -----------------------------------------------------------------------------
# *** Test 1 - update one field

response = my_col.update_one(
    {'name': 'Ron'},  # Search for name = Ron
    {'$set': {'IQ': 55.8}},  # Update only the IQ field
    )

query_result = list(my_col.find({}, {'_id': False}))
pprint(query_result)
# Ron's IQ field has been updated, without changing any other fields:
# [{'IQ': 55.8, 'hair_colour': 'ginger', 'name': 'Ron'},
#  {'IQ': 178.5, 'hair_colour': 'brown', 'name': 'Hermione'}]


# -----------------------------------------------------------------------------
# *** Test 2 - insert extra field in existing document

response = my_col.update_one(
    {'name': 'Hermione'},  # Search for name = Hermione
    {'$set': {'house': 'Gryffindor'}},  # Add a new field
    )

query_result = list(my_col.find({}, {'_id': False}))
pprint(query_result)
# Adding a new field doesn't change the existing fields:
# [{'IQ': 55.8, 'hair_colour': 'ginger', 'name': 'Ron'},
#  {'IQ': 178.5,
#   'hair_colour': 'brown',
#   'house': 'Gryffindor',
#   'name': 'Hermione'}]

client.close()