Introduction:

PyMongo is the official Python driver for MongoDB, which allows Python developers to interact with MongoDB databases effortlessly. It provides a Pythonic and intuitive way to perform database operations like inserting, querying, updating, and deleting data.

The design philosophy follows the "do the simplest thing that could work" approach, which aligns perfectly with Python's philosophy. It offers a simple, high-level API that makes it easy to work with MongoDB without requiring extensive knowledge of MongoDB's internal mechanisms.

Prerequisites:

MongoDB Atlas account with Database instance/server

Basics of Flask

Steps:

Installation:

If you don’t have a MongoDB Atlas account or don’t know how to connect to the MongoDB server follow this article How to create a free MongoDB database using MongoDB Atlas cloud

Install Pymongo Python Library. For reference visit this website https://pymongo.readthedocs.io/en/stable/installation.html

pip install pymongo

Initialization:

Initialize the MongoDB using the connection string

from pymongo import *


mongodb_url = "mongodb+srv://test-user:cVwO9ydtF8x04YL4@test-db.pfhwpga.mongodb.net/?retryWrites=true&w=majority"
pymongo_client = MongoClient(mongodb_url)
pymongo_db = pymongo_client['pymongo_db']
student_collection = pymongo_client['student_list']

Step 1: Create data

we don't need to define the collection structure (table). We can add any number of fields while the data complexity increases.

To create a single entry

def createData():
    student_collection.insert_one(
        {"name": "Shana Stevens", "email": "shana@gmail.com", "roll_no": 1}
    )

To create multiple entries at a time

def createData():
    student_collection.insert_many([
        {"name": "Benjamin Lane", "email": "benjamin@gmail.com", "roll_no": 2},
        {"name": "Angela Kemp", "email": "angela@gmail.com", "roll_no": 3},
        {"name": "Roy Nicholson", "email": "roy@gmail.com", "roll_no": 4},
    ])

To avoid data duplication first, you have to check the entry already present in the Database. If the data is present Pymongo returns a dictionary containing the data of the given document. If the document is not present in the database Pymongo returns None.

You have to pass a field which is unique for the particular document you’re searching.

def createData():
    student_object = student_collection.find_one({"email": "shana@gmail.com"})
    if student_object == None:
        student_collection.insert_one(
            {"name": "Shana Stevens", "email": "shana@gmail.com", "roll_no": 1}
        )
    else:
        print("The document already exists")

Step 2: Retrieve data

Retrieve group of entries:

def getBulkData():
    student_objects = student_collection.find({"location": "india"})
    for item in student_objects:
        print(item["email"])

Retrieve single entry:

def getSingleData():
    student_instance = student_collection.find_one({"email": "shana@gmail.com"})
    if student_instance != None:
        print(student_instance["email"] )
    else:
        print("Entry not found!")

Step 3: Update data

In order to update a document first you have to check whether already is it present in the Database.

If the document is present, then you can update the fields of the document.

if the document is not present, display an error message.

def  updateData():

    student_instance = student_collection.find_one({"email": "shana@gmail.com"})
    if student_instance != None:
        query = {"email": "shana@gmail.com"}
        new_values = {"$set": {"name": "shana"}}
        student_collection.update_one(query, new_values)
    else:
        print("Entry not found!")

Step 4: Delete data

Before deleting the data, check if the entry exists in the database if present delete the entry

If data is not present, throw a “data not available” error message.

def deleteData():
    student_instance = student_collection.find_one({"email": "shana@gmail.com"})
    if student_instance != None:
        student_collection.delete_one({"email": "shana@gmail.com"})
    else:
        print("Entry not found!")

Result:

Using the above-given code you can perform the CURD operation on MongoDB using Pymongo library.

How to perform CURD operation on MongoDB using FLask and Pymongo?