How to Create an incremental ID in a Class in Python

# Table of Contents

1. Create an incremental ID in a Class in Python
2. Specifying a different count value to start from
3. Creating an incremental ID in a Class manually

# Create an incremental ID in a Class in Python

To create an incremental ID in a class:

1. Use the itertools.count() method to get an auto-incrementing count object.
2. Assign the id instance variable to the result of calling next() with the count object.
3. Each class instance will have a unique id attribute.

Copied!
import itertools


class Employee():
    id_obj = itertools.count()

    def __init__(self, name, salary):
        self.id = next(Employee.id_obj)
        self.name = name
        self.salary = salary


alice = Employee('Alice', 100)
bob = Employee('Bobbyhadz', 100)
carl = Employee('Carl', 100)

print(alice.id)  # 👉️ 0
print(bob.id)  # 👉️ 1
print(carl.id)  # 👉️ 2

We used the itertools.count() method to make an iterator that returns an auto-incrementing count object.

Copied!
import itertools

id_obj = itertools.count()

print(next(id_obj))  # 👉️ 0
print(next(id_obj))  # 👉️ 1
print(next(id_obj))  # 👉️ 2

Notice that we assign the id attribute of each instance in the __init__() method to the result of calling next() with the count object.

# Specifying a different count value to start from

You can specify a value for the start argument if you need to create an incremental ID that starts at 1 or any other value.

Copied!
import itertools


class Employee():
    # 👇️ Start incremental ID at 1
    id_obj = itertools.count(1)

    def __init__(self, name, salary):
        self.id = next(Employee.id_obj)
        self.name = name
        self.salary = salary


alice = Employee('Alice', 100)
bob = Employee('Bobbyhadz', 100)
carl = Employee('Carl', 100)

print(alice.id)  # 👉️ 1
print(bob.id)  # 👉️ 2
print(carl.id)  # 👉️ 3

We specified a value of 1 for the start argument, so the auto-incrementing IDs start at 1.

Each time a class instance is created, the __init__() method runs and its id attribute gets set to the result of calling next() with the count object.

An iterator object represents a stream of data. Every time we pass the iterator to the next() function, the next item in the stream is returned.

# Creating an incremental ID in a Class manually

You can also manually manage the ID attribute by using a class variable.

Copied!
class Employee():
    cls_id = 0

    def __init__(self, name, salary):
        self.id = Employee.cls_id
        self.name = name
        self.salary = salary

        Employee.cls_id += 1


alice = Employee('Alice', 100)
bob = Employee('Bobbyhadz', 100)
carl = Employee('Carl', 100)

print(alice.id)  # 👉️ 0
print(bob.id)  # 👉️ 1
print(carl.id)  # 👉️ 2

The class has a cls_id class variable that is incremented by 1 each time an instance is created.

When an instance is created, the __init__() method runs, where we set the id attribute on the instance to the current cls_id value and increment the value of the cls_id class variable.

You can change the initial value of the cls_id attribute if you need to start counting from a different value.

Copied!
class Employee():
    cls_id = 1

    def __init__(self, name, salary):
        self.id = Employee.cls_id
        self.name = name
        self.salary = salary

        Employee.cls_id += 1


alice = Employee('Alice', 100)
bob = Employee('Bobbyhadz', 100)
carl = Employee('Carl', 100)

print(alice.id)  # 👉️ 1
print(bob.id)  # 👉️ 2
print(carl.id)  # 👉️ 3

The class has an incremental cls_id attribute starting at 1 instead of 0.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• How to get the File path of a Class in Python
• Creating class instances from a Dictionary in Python
• Convert a string to a Class object in Python
• Purpose of 'return self' from a class method in Python
• Call a class method from another Class in Python