Cara menggunakan python getattr call method

The getattr() method returns the value of the named attribute of an object. If not found, it returns the default value provided to the function.

Example

class Student:
  marks = 88
  name = 'Sheeran'

person = Student()

name = getattr(person, 'name')
print(name)

marks = getattr(person, 'marks')
print(marks)

# Output: Sheeran
#         88

getattr() Syntax

The syntax of getattr() method is:

getattr(object, name[, default])

The above syntax is equivalent to:

object.name

getattr() Parameters

getattr() method takes multiple parameters:

• object - object whose named attribute's value is to be returned
• name - string that contains the attribute's name
• default (Optional) - value that is returned when the named attribute is not found

getattr() Return Value

getattr() method returns:

• value of the named attribute of the given object

• getattr(object, name[, default])

  1, if no named attribute is found

• getattr(object, name[, default])

  2 exception, if named attribute is not found and

  getattr(object, name[, default])

  1 is not defined

Example 1: How getattr() works in Python?

class Person:
    age = 23
    name = "Adam"

person = Person()
print('The age is:', getattr(person, "age"))




print('The age is:', person.age)

Output

The age is: 23
The age is: 23

Example 2: getattr() when named attribute is not found

class Person:
    age = 23
    name = "Adam"

person = Person()

# when default value is provided
print('The sex is:', getattr(person, 'sex', 'Male'))

# when no default value is provided
print('The sex is:', getattr(person, 'sex'))

Output

The sex is: Male
AttributeError: 'Person' object has no attribute 'sex'

The named attribute sex is not present in the class Person. So, when calling getattr() method with a default value

getattr(object, name[, default])

But, if we don't provide any default value, when the named attribute sex is not found, it raises an

getattr(object, name[, default])

Before we jump into how getattr can be a useful tool for DRYing up our code, lets cover how it works (docs )! In short, it takes an object and a string version of a property name, and returns the value of that property, if it exists on an object. It can optionally take a default value to return if the attribute can’t be found on the object, and otherwise…

The

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

Syntax:

getattr(object, name, default)

Parameters:

1. object: An object of the class whose attribute value needs to be returned.
2. name: The string name of the attribute.
3. default. (Optional) A value to be returned if the attribute is not found.

Return Value:

• Returns value of the attribute of the given object.
• Returns the specified default value if attribute not found.
• If the default value not specified, then throws

  class student:
      name = 'John'
      age = 18
      
  std = student() # creating object
  
  print('student name is ', getattr(std, 'name'))
  
  std.name = 'Bill' # updating value
  print('student name changed to ', getattr(std, 'name'))
  

  2.

The following example demonstrates the

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

Example: getattr()

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

Output

student name is John
student name changed to Bill

Above,

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

If the attribute specified in the argument is not found, an

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

Example: getattr()

class student:
    name = 'John'
    age = '18'

std = student()
attr = getattr(std, 'subject')

Output

Traceback (most recent call last):
    attr = getattr(std, 'subject')
AttributeError: type object 'student' has no attribute 'subject'

The default parameter can be passed to avoid the above error, which returns the default value if the attribute is not found.

Example: getattr()

class student:
    name = 'John'
    age = '18'

std = student()
subject = getattr(std, 'subject', 'Not supported')
print("student's subject: ", subject)

Output

student's subject: Not supported

Instead of

class student:
    name = 'John'
    age = 18
    
std = student() # creating object

print('student name is ', getattr(std, 'name'))

std.name = 'Bill' # updating value
print('student name changed to ', getattr(std, 'name'))

student name is John
student name changed to Bill