How to Add attributes to an Object in Python

# Table of Contents

1. Add attributes to an Object in Python
2. Add attribute to an Object using dot notation
3. Add multiple attributes to an object using a for loop
4. Add attributes to an Object using SimpleNamespace()

# Add attributes to an Object in Python

Use the setattr() function to add attributes to an object, e.g. setattr(obj, 'name', 'value').

The setattr function takes an object, the name of the attribute and its value as arguments and adds the specified attribute to the object.

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class Employee():
    def __init__(self, name):
        self.name = name


emp1 = Employee('bobby')

setattr(emp1, 'salary', 100)
setattr(emp1, 'age', 30)

print(getattr(emp1, 'salary'))  # 👉️ 100
print(getattr(emp1, 'age'))  # 👉️ 30
print(getattr(emp1, 'name'))  # 👉️ bobby

We instantiated the Employee() class and used the setattr() function to add attributes to the object.

The setattr() function adds an attribute to an object.

The function takes the following 3 arguments:

The name string may be an existing or a new attribute.

If you need to create a generic object, use the pass statement in a class.

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class GenericClass():
    pass

obj1 = GenericClass()

setattr(obj1, 'salary', 100)
setattr(obj1, 'age', 30)

print(getattr(obj1, 'salary'))  # 👉️ 100
print(getattr(obj1, 'age'))  # 👉️ 30

The pass statement does nothing and is used when a statement is required syntactically but the program requires no action.

Make sure your class does not extend from the built-in object class.

# Add attribute to an Object using dot notation

You can also use dot notation to add an attribute to an object.

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class GenericClass():
    pass

obj1 = GenericClass()

obj1.salary = 100
obj1.age = 30

print(getattr(obj1, 'salary'))  # 👉️ 100
print(getattr(obj1, 'age'))  # 👉️ 30

print(obj1.salary)  # 👉️ 100
print(obj1.age)  # 👉️ 30

Using dot notation is equivalent to using the setattr() method.

However, when using dot notation, you might get linting warnings for defining attributes outside of the __init__() method.

# Add multiple attributes to an object using a for loop

You can use a for loop if you need to add multiple attributes to an object.

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class GenericClass():
    pass

my_dict = {'name': 'bobbyhadz', 'age': 30}


obj1 = GenericClass()

for key, value in my_dict.items():
    setattr(obj1, key, value)

print(getattr(obj1, 'name'))  # 👉️ bobbyhadz
print(getattr(obj1, 'age'))  # 👉️ 30

We used a for loop to iterate over a dictionary's items and added the key-value pairs as attributes to the object.

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class GenericClass():
    def __init__(self, dictionary):
        for key, value in dictionary.items():
            setattr(self, key, value)

my_dict = {'name': 'bobbyhadz', 'age': 30}


obj1 = GenericClass(my_dict)

print(getattr(obj1, 'name'))  # 👉️ bobbyhadz
print(getattr(obj1, 'age'))  # 👉️ 30

You can also use the SimpleNamespace class if you need to create a generic object to which you can add attributes.

# Add attributes to an Object using SimpleNamespace()

This is a two-step process:

1. Use the SimpleNamespace class to create an object.
2. Use the setattr() function to add attributes to the object.

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from types import SimpleNamespace

obj1 = SimpleNamespace()

setattr(obj1, 'salary', 100)
setattr(obj1, 'language', 'Python')

print(getattr(obj1, 'salary'))  # 👉️ 100
print(getattr(obj1, 'language'))  # 👉️ Python

print(obj1)  # 👉️ namespace(salary=100, language='Python')

The SimpleNamespace class is a subclass of object and provides attribute access to its namespace.

We can't add attributes to instances of the built-in object class, however, we can attributes to instances of the SimpleNamespace class.

The class can also be initialized with keyword arguments.

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from types import SimpleNamespace

obj1 = SimpleNamespace(name='bobby', age=30)

setattr(obj1, 'salary', 100)
setattr(obj1, 'language', 'Python')

print(getattr(obj1, 'salary'))  # 👉️ 100
print(getattr(obj1, 'language'))  # 👉️ Python

print(getattr(obj1, 'name'))  # 👉️ bobby
print(getattr(obj1, 'age'))  # 👉️ 30

# 👇️ namespace(name='bobby', age=30, salary=100, language='Python')
print(obj1)

The SimpleNamespace class is quite convenient when you need to create a blank object to which you can add attributes.

Attributes cannot be added to the built-in object class, so the SimpleNamespace should be your preferred approach.

# Additional Resources

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

• How to access Parent class Attributes in Python
• Access object attribute by String Name in Python
• How to get all Attributes of an Object in Python
• Iterate over an Object's attributes in Python