Python hasattr() Function

In this Python built-in functions tutorial, we will go through hasattr() function to check whether a specified object has a specific attribute or not. hastattr function in python returns only a Boolean value that means True or False.

Python hasattr() function Introduction

Python hasattr() function is a built-in function that is used to check whether a specified Object has a specified attribute or not. hasattr() function returns a True or False Boolean value. To use hasattr() function in Python, you don’t need to install it or import it from any module or package because it comes with Python default.

Syntax

The syntax of hasattr() function in Python is:-

hasattr(Object, attribute)

Parameter

Python hasattr function takes two parameters:-

• Object:– Required, An Object.
• attribute:- The name of the attribute you want to check if exists.

Return Value

The return value of hasattr() function is True or False.

• True:- if the specified attribute belongs to a specified object
• False:- if the specified attribute does not belong to a specified object

Python hasattr() Function Examples

Here, I am about to explore the Python hasattr() function along with different-different examples.

Example: Using hasattr() function with custom class

class Student:
    first_name = 'Vishvajit'
    last_name = 'Rao'
    roll_no = 120
    course = 'BCA'

    def details(self):
        print(
            f"My name is {self.first_name + self.last_name} and my roll no is {self.roll_no}. I am pursuing {self.course}.")


print(hasattr(Student, 'first_name'))
print(hasattr(Student, 'last_name'))
print(hasattr(Student, 'details'))

Output

True
True
True

If you try to check an attribute that does not belong to a specified object, in That case, it returns False. As shown below.

print(hasattr(Student, 'Country'))
# Output:- False

Example: Using hasattr() function with Python Dictionary

I have a Python dictionary employee, and now I am going to check whether a few specified attributes are the attributes of the employee or not.

# Python dictionary
employee = {"name": "Vishvajit Rao", "occupation": "Developer", "email": "[email protected]"}

print(hasattr(employee, 'update'))
print(hasattr(employee, 'keys'))
print(hasattr(employee, 'pop'))
print(hasattr(employee, 'items'))
print(hasattr(employee, 'values'))
print(hasattr(employee, 'append'))

Output

True
True
True
True
True
False

In the above example, attributes ( ‘update’, ‘keys’, ‘pop’, ‘items’, ‘values’ ) are the attributes employee that’s why hasattr() function has returned True but in the case of ‘append’ attribute, it has returned False because it is not an attribute of the employee.

Note:- To display all the attributes of an object, Python provides an amazing built-in function called dir().dir() function takes an object as a parameter and returns all its attributes.
For example, I am taking both objects employee and Student to display all their attributes.

Attributes of a class Student from the first example:

print(dir(Student))

Output

['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'course', 'details', 'first_name', 'last_name', 'roll_no']

Attributes of an objecting employee of the second example:

# Python dictionary
employee = {"name": "Vishvajit Rao", "occupation": "Developer", "email": "[email protected]"}
print("Attributes of employee:- ", dir(employee))

Output

Attributes of employee:-  ['__class__', '__class_getitem__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__ior__', '__iter__', '__le__', '__len__', '__lt__', '__ne__', '__new__', '__or__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__ror__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'clear', 'copy', 'fromkeys', 'get', 'items', 'keys', 'pop', 'popitem', 'setdefault', 'update', 'values']

Conclusion

In this tutorial, you have learned all about Python hasattr function to check whether a specified object has a specified attribute or not. If the specified object has a specified attribute, Then it will return True otherwise it will return False.

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Other Python Built-in Functions

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