Python MongoDB Tutorial – Delete Document with PyMongo

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Tags:- Python MongoDB

Deleting documents in a MongoDB collection is a fundamental operation, especially when managing data that is outdated, incorrect, or no longer needed. With PyMongo, Python developers can easily perform deletion operations using intuitive methods.

In this tutorial, you'll learn how to delete documents from MongoDB collections using Python’s PyMongo library.


Table of Contents

  1. Introduction

  2. Prerequisites

  3. Installing PyMongo

  4. Connecting to MongoDB

  5. Inserting Sample Data

  6. Deleting a Single Document (delete_one)

  7. Deleting Multiple Documents (delete_many)

  8. Deleting All Documents

  9. Deleting with Query Conditions

  10. Complete Working Example

  11. Tips and Common Pitfalls


1. Introduction

MongoDB provides two main methods for deleting documents:

  • delete_one() – deletes the first matching document.

  • delete_many() – deletes all matching documents.

Both return a result object that provides metadata, such as the number of documents deleted.


⚙️ 2. Prerequisites

  • Python 3.x installed

  • MongoDB server running locally or via MongoDB Atlas

  • Basic understanding of Python and MongoDB collections


3. Installing PyMongo

To install the PyMongo library, use pip:

pip install pymongo

4. Connecting to MongoDB

Local MongoDB connection:

import pymongo

client = pymongo.MongoClient("mongodb://localhost:27017/")
db = client["mydatabase"]
collection = db["users"]

5. Inserting Sample Data

Let’s insert some test users into the users collection:

collection.insert_many([
    {"name": "Alice", "age": 25},
    {"name": "Bob", "age": 30},
    {"name": "Charlie", "age": 35},
    {"name": "Alice", "age": 28}
])

Now you have two documents with the name "Alice".


❌ 6. Deleting a Single Document

Use delete_one() to remove the first matching document:

result = collection.delete_one({"name": "Alice"})
print(f"Deleted {result.deleted_count} document.")

Only one of the "Alice" records will be deleted, even though there are two.


7. Deleting Multiple Documents

To delete all documents matching a condition, use delete_many():

result = collection.delete_many({"name": "Alice"})
print(f"Deleted {result.deleted_count} documents.")

Both "Alice" records will be deleted if you haven't already deleted one with delete_one().


8. Deleting All Documents

To delete all documents in a collection:

result = collection.delete_many({})
print(f"Deleted {result.deleted_count} documents.")

⚠️ Warning: This removes everything in the collection.


9. Deleting with Query Conditions

You can delete based on any condition or combination of conditions:

Example: Delete users older than 30

result = collection.delete_many({"age": {"$gt": 30}})
print(f"Deleted {result.deleted_count} documents.")

This will delete users like Charlie (age 35).


10. Complete Working Example

import pymongo

# Connect to MongoDB
client = pymongo.MongoClient("mongodb://localhost:27017/")
db = client["mydatabase"]
collection = db["users"]

# Insert sample data
collection.insert_many([
    {"name": "Alice", "age": 25},
    {"name": "Bob", "age": 30},
    {"name": "Charlie", "age": 35},
    {"name": "Alice", "age": 28}
])

# Delete one Alice
res1 = collection.delete_one({"name": "Alice"})
print(f"Deleted {res1.deleted_count} document.")

# Delete all remaining users named Alice
res2 = collection.delete_many({"name": "Alice"})
print(f"Deleted {res2.deleted_count} documents.")

# Delete users older than 30
res3 = collection.delete_many({"age": {"$gt": 30}})
print(f"Deleted {res3.deleted_count} documents.")

# Optional: Clean up all
# res4 = collection.delete_many({})
# print(f"Deleted {res4.deleted_count} documents.")

11. Tips and Common Pitfalls

Tip / Pitfall Advice or Explanation
Deleting without conditions Always double-check your filters to avoid mass deletion
delete_one() deletes only one match If multiple documents match, only the first one is deleted
Check deleted_count Useful for logging and debugging
Use confirmation before deletion Especially for bulk or unconditional deletions
Back up critical data Before running any delete operation in production

✅ Conclusion

Deleting documents from MongoDB using Python is efficient and easy with PyMongo. Whether you need to remove one document or many based on conditions, PyMongo provides straightforward methods to handle it.

By mastering deletion operations, you ensure better data hygiene and application performance.

 

Tips and Tricks


What is pass in Python?

Python | Pass Statement

The pass statement is used as a placeholder for future code. It represents a null operation in Python. It is generally used for the purpose of filling up empty blocks of code which may execute during runtime but has yet to be written.

 

def myfunction():
    pass

 


How can you generate random numbers?

Python | Generate random numbers

Python provides a module called random using which we can generate random numbers. e.g: print(random.random())

 

 

We have to import a random module and call the random() method as shown below:

 import random

 print(random.random())

The random() method generates float values lying between 0 and 1 randomly.


To generate customized random numbers between specified ranges, we can use the randrange() method
Syntax: randrange(beginning, end, step)
 

import random

print(random.randrange(5,100,2))

 


What is lambda in Python?

Python | Lambda function

A lambda function is a small anonymous function. This function can have any number of parameters but, can have just one statement.
 

 

Syntex: 
lambda arguments : expression
 

a = lambda x,y : x+y

print(a(5, 6))

It also provides a nice way to write closures. With that power, you can do things like this.

def adder(x):
    return lambda y: x + y

add5 = adder(5)

add5(1)    #6

As you can see from the snippet of Python, the function adder takes in an argument x and returns an anonymous function, or lambda, that takes another argument y. That anonymous function allows you to create functions from functions. This is a simple example, but it should convey the power lambdas and closures have.
 


What is swapcase() function in the Python?

Python | swapcase() Function

It is a string's function that converts all uppercase characters into lowercase and vice versa. It automatically ignores all the non-alphabetic characters.
 

string = "IT IS IN LOWERCASE."  

print(string.swapcase())  

 


How to remove whitespaces from a string in Python?

Python | strip() Function | Remove whitespaces from a string 

To remove the whitespaces and trailing spaces from the string, Python provides a strip([str]) built-in function. This function returns a copy of the string after removing whitespaces if present. Otherwise returns the original string.
 

string = "  Python " 
 
print(string.strip())  

 


What is the usage of enumerate() function in Python?

Python | enumerate() Function

The enumerate() function is used to iterate through the sequence and retrieve the index position and its corresponding value at the same time.
 

lst = ["A","B","C"] 
 
print (list(enumerate(lst)))

#[(0, 'A'), (1, 'B'), (2, 'C')]

 


Can you explain the filter(), map(), and reduce() functions?

Python | filter(), map(), and reduce() Functions

  • filter()  function accepts two arguments, a function and an iterable, where each element of the iterable is filtered through the function to test if the item is accepted or not.
    >>> set(filter(lambda x:x>4, range(7)))
    
    # {5, 6}
    
    

     

  • map() function calls the specified function for each item of an iterable and returns a list of result

    >>> set(map(lambda x:x**3, range(7)))
    
    # {0, 1, 64, 8, 216, 27, 125}

     

  • reduce() function reduces a sequence pair-wise, repeatedly until we arrive at a single value..
     

    >>> reduce(lambda x,y:y-x, [1,2,3,4,5])
    
    # 3
    

    Let’s understand this:

    2-1=1
    3-1=2
    4-2=2
    5-2=3

    Hence, 3.

 


What is a namedtuple?

Python | namedtuple

A namedtuple will let us access a tuple’s elements using a name/label. We use the function namedtuple() for this, and import it from collections.

>>> from collections import namedtuple

#format
>>> result=namedtuple('result','Physics Chemistry Maths') 

#declaring the tuple
>>> Chris=result(Physics=86,Chemistry=92,Maths=80) 

>>> Chris.Chemistry
# 92

 


Write a code to add the values of same keys in two different dictionaries and return a new dictionary.

We can use the Counter method from the collections module

from collections import Counter

dict1 = {'a': 5, 'b': 3, 'c': 2}
dict2 = {'a': 2, 'b': 4, 'c': 3}

new_dict = Counter(dict1) + Counter(dict2)


print(new_dict)
# Print: Counter({'a': 7, 'b': 7, 'c': 5})


 


Python In-place swapping of two numbers

 Python | In-place swapping of two numbers

>>> a, b = 10, 20
>>> print(a, b)
10 20

>>> a, b = b, a
>>> print(a, b)
20 10

 


Reversing a String in Python

Python | Reversing a String

>>> x = 'PythonWorld'
>>> print(x[: : -1])
dlroWnohtyP

 


Python join all items of a list to convert into a single string

Python | Join all items of a list to convert into a single string

>>> x = ["Python", "Online", "Training"]
>>> print(" ".join(x))
Python Online Training

 


python return multiple values from functions

Python | Return multiple values from functions

>>> def A():
	return 2, 3, 4

>>> a, b, c = A()

>>> print(a, b, c)
2 3 4

 


Python Print String N times

Python | Print String N times

>>> s = 'Python'
>>> n = 5

>>> print(s * n)
PythonPythonPythonPythonPython

 


Python check the memory usage of an object

Python | Check the memory usage of  an object

>>> import sys
>>> x = 100

>>> print(sys.getsizeof(x))
28