MongoClient. MongoDB is a fast database for storing data (documents) with no complex relational logic. It can be used through direct Python method calls.
Local database. This tutorial uses a local database on a Windows computer. It uses the Community release of MongoDB. The mongo.exe and mongod.exe programs must be run first.
Example program. Here we use the MongoClient object. We must pass a connection string to MongoClient—this is acquired by running mongo.exe.
Tip We must run mongod.exe and then mongo.exe to begin using MongoDB. We can then connect in a Python program.
Here We use example_database and example_collection, but you can specify other names (and should).
from pymongo import MongoClient
# Run mongod.exe before running this program.# Run mongo.exe to get the database connection string.
client = MongoClient("mongodb://127.0.0.1:27017")
# Specify the database name after the client object.
db = client.example_database
# Ensure everything is deleted from example collection.# ... The name can anything to specify a collection.
db.example_collection.delete_many({})
db.example_collection.insert_many([
{"type": "cat", "weight": 25, "color": "orange"},
{"type": "dog", "weight": 35, "color": "black"},
{"type": "cat", "weight": 10, "color": "black"}
])
# Find all things.
cursor = db.example_collection.find({})
print("FIND ALL")
for c in cursor:
print(c)
# Find all animals that are black.
cursor = db.example_collection.find({"color": "black"})
print("FIND COLOR BLACK")
for c in cursor:
print(c)
# Find all dogs.
cursor = db.example_collection.find({"type": "dog"})
print("FIND DOG")
for c in cursor:
print(c)FIND ALL
{'type': 'cat', 'weight': 25, 'color': 'orange',
'_id': ObjectId('59ee4d922514973b084100a7')}
{'type': 'dog', 'weight': 35, 'color': 'black',
'_id': ObjectId('59ee4d922514973b084100a8')}
{'type': 'cat', 'weight': 10, 'color': 'black',
'_id': ObjectId('59ee4d922514973b084100a9')}
FIND COLOR BLACK
{'type': 'dog', 'weight': 35, 'color': 'black',
'_id': ObjectId('59ee4d922514973b084100a8')}
{'type': 'cat', 'weight': 10, 'color': 'black',
'_id': ObjectId('59ee4d922514973b084100a9')}
FIND DOG
{'type': 'dog', 'weight': 35, 'color': 'black',
'_id': ObjectId('59ee4d922514973b084100a8')}
Notes, program. The program creates a database called example_database. It then creates a collection in the database called example_collection.
Then It uses delete_many with an empty dictionary argument to clear any existing data.
Notes, insert_many. We pass a dictionary argument to insert_many. Many rows (called documents) are added to the MongoDB collection.
Detail In MongoDB we insert documents into collections. In an SQL database we insert rows into tables.
ObjectId. We do not specify a "_id" in the insert_many method call. The objects are added with an ObjectId automatically. This is a feature of MongoDB.
Find. We can pass an empty dictionary to find() to find all documents (all rows). If we specify a key-value pair, all documents that match are returned.
In Python we can use a free and powerful NoSQL database. We use MongoClient to store documents in collections (which are inside databases).
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Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.