Nonetype object has no attribute append ошибка - Решение и исправление самых разных ошибок на TopOshibok.ru

I have a script in which I am extracting value for every user and adding that in a list but I am getting «‘NoneType’ object has no attribute ‘append'». My code is like

last_list=[]
if p.last_name==None or p.last_name=="": 
    pass
last_list=last_list.append(p.last_name)
print last_list

I want to add last name in list. If its none then dont add it in list . Please help
Note:p is the object that I am using to get info from my module which have all first_name ,last_name , age etc…. Please suggest ….Thanks in advance

LBes

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asked Oct 15, 2012 at 11:35

list is mutable

Change

last_list=last_list.append(p.last_name)

last_list.append(p.last_name)

will work

Uma Madhavi

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answered Apr 29, 2017 at 7:18

jessiejcjsjzjessiejcjsjz

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When doing pan_list.append(p.last) you’re doing an inplace operation, that is an operation that modifies the object and returns nothing (i.e. None).

You should do something like this :

last_list=[]
if p.last_name==None or p.last_name=="": 
    pass
last_list.append(p.last)  # Here I modify the last_list, no affectation
print last_list

answered Oct 15, 2012 at 11:52

Cédric JulienCédric Julien

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You are not supposed to assign it to any variable, when you append something in the list, it updates automatically.
use only:-

last_list.append(p.last)

if you assign this to a variable «last_list» again, it will no more be a list (will become a none type variable since you haven’t declared the type for that)
and append will become invalid in the next run.

answered Jan 1, 2020 at 13:45

I think what you want is this:

last_list=[]
if p.last_name != None and p.last_name != "":
    last_list.append(p.last_name)
print last_list

Your current if statement:

if p.last_name == None or p.last_name == "":
    pass

Effectively never does anything. If p.last_name is none or the empty string, it does nothing inside the loop. If p.last_name is something else, the body of the if statement is skipped.

Also, it looks like your statement pan_list.append(p.last) is a typo, because I see neither pan_list nor p.last getting used anywhere else in the code you have posted.

answered Oct 15, 2012 at 11:56

Joe DayJoe Day

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Источник

If you attempt to call the append() method on a variable with a None value, you will raise the error AttributeError: ‘NoneType’ object has no attribute ‘append’. To solve this error, ensure you are not assigning the return value from append() to a variable. The Python append() method updates an existing list; it does not return a new list.

This tutorial will go through how to solve this error with code examples.

AttributeError: ‘NoneType’ object has no attribute ‘append’
Example
- Solution
Summary

AttributeError: ‘NoneType’ object has no attribute ‘append’

AttributeError occurs in a Python program when we try to access an attribute (method or property) that does not exist for a particular object. The part “‘NoneType’ object has no attribute ‘append’” tells us that the NoneType object does not have the attribute append(). The append() method belongs to the List data type, and appends elements to the end of a list.

A NoneType object indicates no value:

obj = None
print(type(obj))

<class 'NoneType'>

Let’s look at the syntax of the append method:

list.append(element)

Parameters:

element: Required. An element of any type to append.

The append method does not return a value, in other words, it returns None. If we assign the result of the append() method to a variable, the variable will be a NoneType object.

Example

Let’s look at an example where we have a list of strings, and we want to append another string to the list. First, we will define the list:

# List of planets

planets = ["Jupiter", "Mars", "Neptune", "Saturn"]

planets = planets.append("Mercury")

print(planets)

planets = planets.append("Venus")

print(f'Updated list of planets: {planets}')

Let’s run the code to see what happens:

None
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
      5 planets = planets.append("Mercury")
      6 
----≻ 7 planets = planets.append("Venus")
      8 
      9 print(f'Updated list of planets: {planets}')

AttributeError: 'NoneType' object has no attribute 'append'

The error occurs because the first call to append returns a None value assigned to the planets variable. Then, we tried to call append() on the planets variable, which is no longer a list but a None value. The append() method updates an existing list; it does not create a new list.

Solution

We need to remove the assignment operation when calling the append() method to solve this error. Let’s look at the revised code:

# List of planets

planets = ["Jupiter", "Mars", "Neptune", "Saturn"]

planets.append("Mercury")

planets.append("Venus")

print(f'Updated list of planets: {planets}')

Let’s run the code to see the result:

Updated list of planets: ['Jupiter', 'Mars', 'Neptune', 'Saturn', 'Mercury', 'Venus']

We update the list of planets by calling the append() method twice. The updated list contains the two new values.

Summary

Congratulations on reading to the end of this tutorial! The error AttributeError: ‘NoneType’ object has no attribute ‘append’ occurs when you call the append() method on a NoneType object. This error commonly occurs if you call the append method and then assign the result to the same variable name as the original list. The append() method returns None, so you will replace the list with a None value by doing this.

For further reading on AttributeErrors, go to the article: How to Solve Python AttributeError: ‘numpy.ndarray’ object has no attribute ‘append’.

Go to the online courses page on Python to learn more about coding in Python for data science and machine learning.

Have fun and happy researching!

Источник

When you’re working with lists in Python, you might get the following error:

AttributeError: 'NoneType' object has no attribute 'append'

This error occurs when you call the append() method on a NoneType object in Python.

This tutorial shows examples that cause this error and how to fix it.

1. calling the `append()` method on a NoneType object

To show you how this error happens, suppose you try to call the append() method on a NoneType object as follows:

fruit_list = None

fruit_list.append("Apple")

In the above example, the fruit_list variable is assigned the None value, which is an instance of the NoneType object.

When you call the append() method on the object, the error gets raised:

Traceback (most recent call last):
  File "main.py", line 3, in <module>
    fruit_list.append("Apple")
AttributeError: 'NoneType' object has no attribute 'append'

To fix this error, you need to call the append() method from a list object.

Assign an empty list [] to the fruit_list variable as follows:

fruit_list = []

fruit_list.append("Apple")

print(fruit_list)  # ['Apple']

This time, the code is valid and the error has been fixed.

2. Assigning `append()` to the list variable

But suppose you’re not calling append() on a NoneType object. Let’s say you’re extracting a list of first names from a dictionary object as follows:

customers = [
    {"first_name": "Lisa", "last_name": "Smith"},
    {"first_name": "John", "last_name": "Doe"},
    {"first_name": "Andy", "last_name": "Rock"},
]

first_names = []

for item in customers:
    first_names = first_names.append(item['first_name'])

At first glance, this example looks valid because the append() method is called on a list.

But instead, an error happens as follows:

Traceback (most recent call last):
  File "main.py", line 11, in <module>
    fruit_list = fruit_list.append(item['first_name'])
AttributeError: 'NoneType' object has no attribute 'append'

This is because the append() method returns None, so when you do an assignment inside the for loop like this:

first_names = first_names.append(item['first_name'])

The first_names variable becomes a None object, causing the error on the next iteration of the for loop.

You can verify this by printing the first_names variable as follows:

for item in customers:
    first_names = first_names.append(item['first_name'])
    print(first_names)

The for loop will run once before raising the error as follows:

None
Traceback (most recent call last):

As you can see, first_names returns None and then raises the error on the second iteration.

To resolve this error, you need to remove the assignment line and just call the append() method:

customers = [
    {"first_name": "Lisa", "last_name": "Smith"},
    {"first_name": "John", "last_name": "Doe"},
    {"first_name": "Andy", "last_name": "Rock"},
]

first_names = []

for item in customers:
    first_names.append(item["first_name"])

print(first_names)

Output:

Notice that you receive no error this time.

Conclusion

The error “NoneType object has no attribute append” occurs when you try to call the append() method from a NoneType object. To resolve this error, make sure you’re not calling append() from a NoneType object.

Unlike the append() method in other programming languages, the method in Python actually changes the original list object without returning anything.

Python implicitly returns None when a method returns nothing, so that value gets assigned to the list if you assign the append() result to a variable.

If you’re calling append() inside a for loop, you need to call the method without assigning the return value to the list.

Now you’ve learned how to resolve this error. Happy coding! 😃

Источник

Если вы программист, скорее всего, вы сталкивались с сообщением об ошибке «AttributeError: ‘NoneType’ объект не имеет атрибута ‘append’» в тот или иной момент. Это сообщение об ошибке может разочаровать, так как оно часто не дает вам много информации о том, почему это произошло. В этом посте мы более подробно рассмотрим, что вызывает эту ошибку и как ее можно исправить.

Понимание сообщения об ошибке

Прежде чем мы углубимся в причины сообщения об ошибке, давайте сначала рассмотрим, что оно на самом деле означает. Проще говоря, сообщение об ошибке сообщает вам, что вы пытаетесь вызвать append() метод на объекте, который None. В Питоне, None — это специальный объект, представляющий отсутствие значения.

Объект, который None не имеет никаких атрибутов, в том числе append(). Когда вы пытаетесь позвонить append() на None объект, вы получаете сообщение об ошибке «AttributeError: объект NoneType не имеет атрибута« добавить »».

Распространенные причины ошибки

Теперь, когда мы знаем, что означает сообщение об ошибке, давайте рассмотрим некоторые распространенные причины этой ошибки:

1. Забыли присвоить значение переменной

Одной из частых причин сообщения об ошибке «AttributeError: объект NoneType не имеет атрибута« добавить »» является то, что вы забыли присвоить значение переменной перед попыткой ее использования.

Например, предположим, что у вас есть следующий код:

my_list = None
my_list.append(1)