hasattr()

hasattr(object, name)

Returns: bool · Updated March 13, 2026 · Built-in Functions

built-in attributes introspection objects

The hasattr() function checks whether an object has a named attribute. It returns True if the attribute exists (either on the object itself or inherited from its class), and False if it doesn’t exist. This is useful for writing defensive code that checks for optional features before using them.

Syntax

hasattr(object, name)

Parameters

Parameter	Type	Default	Description
`object`	object	—	Any Python object (class, instance, module, etc.)
`name`	str	—	The attribute name as a string

Examples

Basic usage

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

person = Person("Alice")

print(hasattr(person, "name"))
# True

print(hasattr(person, "age"))
# False

Checking for methods

text = "hello world"

print(hasattr(text, "upper"))
# True

print(hasattr(text, "not_a_method"))
# False

Checking for module attributes

import os

print(hasattr(os, "path"))
# True

print(hasattr(os, "nonexistent"))
# False

Common Patterns

Safe attribute access pattern

Use hasattr() together with getattr() to safely access attributes that may or may not exist:

def get_description(obj):
    if hasattr(obj, "description"):
        return getattr(obj, "description")
    return "No description available"

Checking for optional features

def process_data(data):
    # Check if data has certain methods before processing
    if hasattr(data, "to_dict"):
        data = data.to_dict()
    
    if hasattr(data, "validate"):
        data.validate()
    
    return data

Dynamic feature detection

import sys

def check_python_version():
    # Check if certain features are available
    if hasattr(sys, "version_info"):
        print(f"Python {sys.version_info.major}.{sys.version_info.minor}")
    
    if hasattr(sys, "flags"):
        print(f"Flags: {sys.flags}")

Class attribute checking

class Animal:
    species = "Generic"

dog = Animal()

print(hasattr(dog, "species"))
# True

print(hasattr(dog, "breed"))
# False

print(hasattr(Animal, "species"))
# True

Errors

The hasattr() function itself does not raise exceptions—it always returns a boolean. However, the attribute name must be a string. Passing a non-string will raise a TypeError:

hasattr(person, 123)
# TypeError: hasattr(): attribute name must be string

Also note that hasattr() returns True even for attributes that raise exceptions when accessed (such as properties that always raise). This is because hasattr() only checks for existence, not whether accessing the attribute will succeed:

class Broken:
    @property
    def bad(self):
        raise ValueError("This property always fails")

obj = Broken()
print(hasattr(obj, "bad"))
# True — attribute exists

print(obj.bad)
# ValueError: This property always fails