MongoDB and Python (original) (raw)

MongoDB is an open-source NoSQL database that stores data in flexible, JSON-like documents (BSON format).

Handles large, unstructured or semi-structured data efficiently
Adapts easily to changing data models
Supports fast read/write operations for real-time applications and APIs
Integrates seamlessly with Python using libraries like pymongo

MongoDB vs RDBMS

Connecting MongoDB with Python Using PyMongo

Step 1: Start MongoDB

Start MongoDB from the command prompt using the following command:

If starting with default settings:

mongod

When running directly with custom data directory:

mongod --dbpath "C:\data"

If MongoDB is installed as a Windows service:

net start MongoDB

terminal_mongodb

Snapshot of terminal to show Mongodb runs on port 27017

See port number by default is set 27017 (last 2-3 lines in above image).

Step 2: Install and Import PyMongo

PyMongo is the native Python library for MongoDB. To install PyMongo, open Command Prompt and run:

pip install pymongo

After installation, open a Python environment and import the library:

from pymongo import MongoClient

Step 3: Connect to MongoDB Server Locally

To connect to a local MongoDB server, create a MongoClient object:

client = MongoClient()

Connect to the default MongoDB host and port (localhost:27017) using the following command to create a MongoClient explicitly.

client = MongoClient("mongodb://localhost:27017/")

Step 4: Connect to MongoDB Atlas (Cloud Database)

To connect to a cloud-based MongoDB database like MongoDB Atlas, follow these steps:

**1. Create a MongoDB Atlas Account: Go to MongoDB Atlas and create an account if you don't already have one. Once logged in, create a new project, cluster, and database.

**2. Get the Connection String: After creating the cluster, navigate to the Clusters tab, click Connect, and choose Connect your application. Select Python and copy the provided connection string.

**3. Connection string typically looks like this:

mongodb+srv://:@cluster0.mongodb.net/test?retryWrites=true&w=majority

**4. Use the Connection String: Replace and with your MongoDB Atlas credentials.

client = MongoClient("mongodb+srv://:@cluster0.mongodb.net/test?retryWrites=true&w=majority")

This will connect your Python application to the cloud-based MongoDB cluster.

Step 5: Access/Create a Database

To create a database or switch to an existing database use:

mydatabase = client["my_database"]

Or:

mydatabase = client.my_database

**Note: Database names should not contain dashes (-). The names like my-Table will raise an error. Use **underscores (_) instead.

Step 6: Access/Create a Collection

Collections are equivalent to Tables in Relational Database Management Systems (RDBMS). A collection in PyMongo is accessed similarly to how tables are accessed in RDBMS.

To access the table, table name "myTable" of the database "mydatabase".

mycollection = mydatabase["myTable"]

MongoDB store the database in the form of dictionaries as shown:

record = {
"title": "MongoDB and Python",
"description": "MongoDB is no SQL database",
"tags": ["mongodb", "database", "NoSQL"],
"viewers": 104
}

'_id' is a 12 bytes hexadecimal number. A special key which uniquely identifies each document in a collection and automatically added when not added explicitly.

_id

Step 7: Inserting data inside collection

Methods used:

insert_one() or insert_many()

Insert the document into a collection:

rec = mycollection.insert_one(record)

The complete code looks like this when implemented:

Python `

from pymongo import MongoClient client=MongoClient()

client = MongoClient("mongodb://localhost:27017/")

mydb = client["my_database"] mycollection = mydb["myTable"]

record = { "title": "MongoDB and Python", "description": "MongoDB is no SQL database", "tags": ["mongodb", "database", "NoSQL"], "viewers": 104 }

rec = mycollection.insert_one(record)

Step 8: Querying the Database

Certain query functions are used to filter data in a MongoDB database. Among them, the two most commonly used are:

**find(): used to retrieve multiple documents from a collection that match a given query.

Python `

for i in mycollection.find({"title": "MongoDB and Python"}): print(i)

**count_documents(): used to count the number of documents in a collection that match a specific query.

Python `

count = mycollection.count_documents({"title": "MongoDB and Python"}) print(count)

To print all the documents/entries inside 'myTable' of database 'mydatabase':

Python `

from pymongo import MongoClient

try: conn = MongoClient("localhost", 27017) print("Connected successfully!") except Exception as e: print("Could not connect to MongoDB:", e)

db = conn["mydatabase"]

collection = db["myTable"] for record in collection.find(): print(record)