
When working with databases, sorting data is crucial for presenting results in a meaningful order. Whether you're listing users by signup date, prices in ascending order, or names alphabetically, sorting makes your data easier to interpret.
In this tutorial, you’ll learn how to sort documents in MongoDB using Python and PyMongo.
Table of Contents
-
Introduction to Sorting in MongoDB
-
Prerequisites
-
Installing PyMongo
-
Connecting to MongoDB
-
Inserting Sample Data
-
Basic Sorting Using
sort()
-
Sorting in Descending Order
-
Sorting by Multiple Fields
-
Sorting with Filters
-
Complete Working Example
-
Tips and Common Pitfalls
1. Introduction to Sorting in MongoDB
MongoDB allows you to sort documents using the sort()
method. You can sort by:
-
A single field (ascending or descending)
-
Multiple fields (for secondary sorting)
In PyMongo, sorting is achieved using the collection.find().sort()
method.
⚙️ 2. Prerequisites
-
Python 3.x
-
MongoDB installed or running on MongoDB Atlas
-
Basic knowledge of Python dictionaries
3. Installing PyMongo
Use pip to install PyMongo:
pip install pymongo
4. Connecting to MongoDB
Connect to a local MongoDB server:
import pymongo
client = pymongo.MongoClient("mongodb://localhost:27017/")
Connect to MongoDB Atlas (Cloud):
client = pymongo.MongoClient("mongodb+srv://<username>:<password>@<cluster>.mongodb.net/?retryWrites=true&w=majority")
5. Inserting Sample Data
Insert a sample collection for sorting:
db = client["mydatabase"]
collection = db["products"]
collection.insert_many([
{"name": "Laptop", "price": 999, "rating": 4.5},
{"name": "Phone", "price": 599, "rating": 4.7},
{"name": "Tablet", "price": 399, "rating": 4.2},
{"name": "Monitor", "price": 199, "rating": 4.3},
{"name": "Keyboard", "price": 49, "rating": 4.1}
])
6. Basic Sorting Using sort()
Sort products by price (ascending):
for product in collection.find().sort("price", 1):
print(product)
Output:
Keyboard → Monitor → Tablet → Phone → Laptop
7. Sorting in Descending Order
Sort products by rating in descending order:
for product in collection.find().sort("rating", -1):
print(product)
Output:
Phone → Laptop → Monitor → Tablet → Keyboard
-
1
= Ascending order -
-1
= Descending order
8. Sorting by Multiple Fields
You can sort by multiple fields by passing a list of tuples.
Example: Sort by rating (desc), then price (asc):
for product in collection.find().sort([("rating", -1), ("price", 1)]):
print(product)
This is useful when ratings are the same and you want to break ties by price.
9. Sorting with Filters
Combine filtering and sorting:
query = {"price": {"$gt": 100}}
for product in collection.find(query).sort("price", 1):
print(product)
Output:
Products over $100 sorted by price ascending.
10. Complete Working Example
import pymongo
# Connect to MongoDB
client = pymongo.MongoClient("mongodb://localhost:27017/")
db = client["mydatabase"]
collection = db["products"]
# Insert sample data if empty
if collection.count_documents({}) == 0:
collection.insert_many([
{"name": "Laptop", "price": 999, "rating": 4.5},
{"name": "Phone", "price": 599, "rating": 4.7},
{"name": "Tablet", "price": 399, "rating": 4.2},
{"name": "Monitor", "price": 199, "rating": 4.3},
{"name": "Keyboard", "price": 49, "rating": 4.1}
])
print("Sorted by price (ascending):")
for p in collection.find().sort("price", 1):
print(p)
print("\nSorted by rating (descending):")
for p in collection.find().sort("rating", -1):
print(p)
print("\nSorted by rating DESC then price ASC:")
for p in collection.find().sort([("rating", -1), ("price", 1)]):
print(p)
11. Tips and Common Pitfalls
Tip / Pitfall | Explanation |
---|---|
Use 1 for ascending, -1 for descending |
Common mistake is passing "asc" or "desc" strings |
Sorting large datasets can be slow | Use indexing in MongoDB for better performance |
Field must exist in all documents | Missing fields may result in unexpected order |
Combine sort with limit() for pagination |
Efficiently retrieve top N records |
✅ Conclusion
Sorting is essential for readable and organized output in any application. With PyMongo, sorting documents in MongoDB is straightforward using the sort()
method. Whether you're sorting by one or multiple fields, ascending or descending, PyMongo offers full flexibility.
Now you're equipped to sort any MongoDB data using Python like a pro!
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