Cara menggunakan python getattr function call

❮ Built-in Functions

Example

Get the value of the "age" property of the "Person" object:

class Person:
  name = "John"
  age = 36
  country = "Norway"

x = getattr(Person, 'age')

Definition and Usage

The getattr() function returns the value of the specified attribute from the specified object.

Syntax

getattr(object, attribute, default)

Parameter Values

More Examples

Example

Use the "default" parameter to write a message when the attribute does not exist:

class Person:
  name = "John"
  age = 36
  country = "Norway"

x = getattr(Person, 'page', 'my message')

Related Pages

The delattr() function, to remove an attribute

The hasattr() function, to check if an attribute exist

The setattr() function, to set the value of an attribute

❮ Built-in Functions

Now, we can access the attributes of the

>>> book.title
'Moby Dick'

>>> book.title
'Moby Dick'

We can do the same thing by using

>>> book.title
'Moby Dick'

>>> getattr(book, 'title')
'Moby Dick'

So

>>> book.title
'Moby Dick'

>>> getattr(book, 'title')
'Moby Dick'

• >>> getattr(book, 'title')
  'Moby Dick'

  1 attribute passes as a string (

  >>> getattr(book, 'title')
  'Moby Dick'

  2) to

  >>> book.title
  'Moby Dick'

  5 function.
• You can pass a default value as an argument.

For example:

>>> book.language

will raise an error because the

>>> book.title
'Moby Dick'

Traceback (most recent call last):
  File "<input>", line 1, in <module>
AttributeError: 'Book' object has no attribute 'language'

Instead, we can do:

>>> getattr(book, 'language', 'English')
'English'

Keep in mind that without the default value, it also raises an error.

>>> getattr(book, 'language')

Output:

Traceback (most recent call last):
  File "<input>", line 1, in <module>
AttributeError: 'Book' object has no attribute 'language'

Because

>>> book.title
'Moby Dick'

If you’re adventurous (just like me), you might be wondering whether it is also possible to access a method of a class. Let’s see:

>>> getattr(book, 'describe')

Output:

<bound method Book.describe of <__main__.Book object at 0x103cd7a0>>

It returns

>>> getattr(book, 'title')
'Moby Dick'

>>> book.title
'Moby Dick'

or we can store this value and call it later.

>>> book.title
'Moby Dick'

So far so good! You may ask: Isn’t it weird to access an attribute because we’ve already known the content of a class?

In fact,

>>> book.title
'Moby Dick'

Suppose you make a program that receives inputs from users and prints the value of the desired attribute of

>>> book.title
'Moby Dick'

>>> book.title
'Moby Dick'

Let’s say the user writes

>>> getattr(book, 'title')
'Moby Dick'

>>> book.title
'Moby Dick'

The code above is equivalent to:

>>> book.title
'Moby Dick'

It really shortens our code, right?

Let’s look at another example. Now, you get allowed HTTP methods dynamically from an API, and you send the appropriate HTTP request via requests lib based on the allowed method (POST or PUT). Of course, you need to use

>>> book.title
'Moby Dick'

which is equivalent to:

As you see,

>>> book.title
'Moby Dick'

If you’re in a similar situation and your object has many attributes, using this function saves you from writing many if-elif clauses.

If you really intend to write long code lines because of not using

>>> book.title
'Moby Dick'

In summary, if you know the name of the attribute, always use dot notation. However, when the name of the attribute is given as program flows, you should use

>>> book.title
'Moby Dick'