
Deleting documents in a MongoDB collection is a fundamental operation, especially when managing data that is outdated, incorrect, or no longer needed.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
-
Introduction
-
Prerequisites
-
Installing PyMongo
-
Connecting to MongoDB
-
Inserting Sample Data
-
Deleting a Single Document (
delete_one
) -
Deleting Multiple Documents (
delete_many
) -
Deleting All Documents
-
Deleting with Query Conditions
-
Complete Working Example
-
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=3Hence, 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