Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries

👻 Check our latest review to choose the best laptop for Machine Learning engineers and Deep learning tasks!

I have two classes in my sqlite database, a parent table named Categorie and the child table called Article. I created first the child table class and addes entries. So first I had this:

class Article(models.Model):
    titre=models.CharField(max_length=100)
    auteur=models.CharField(max_length=42)
    contenu=models.TextField(null=True)
    date=models.DateTimeField(
        auto_now_add=True,
        auto_now=False,
        verbose_name="Date de parution"
    )

    def __str__(self):
        return self.titre

And after I have added parent table, and now my models.py looks like this:

from django.db import models

# Create your models here.
class Categorie(models.Model):
    nom = models.CharField(max_length=30)

    def __str__(self):
        return self.nom


class Article(models.Model):
    titre=models.CharField(max_length=100)
    auteur=models.CharField(max_length=42)
    contenu=models.TextField(null=True)
    date=models.DateTimeField(
        auto_now_add=True,
        auto_now=False,
        verbose_name="Date de parution"
    )
    categorie = models.ForeignKey("Categorie")

    def __str__(self):
        return self.titre

So when I run python manage.py makemigrations <my_app_name>, I get this error:

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "C:UserslislisAppDataLocalProgramsPythonPython35-32libsite-packagesdjango-2.0-py3.5.eggdjangocoremanagement\__init__.py", line 354, in execute_from_command_line
    utility.execute()
  File "C:UserslislisAppDataLocalProgramsPythonPython35-32libsite-packagesdjango-2.0-py3.5.eggdjangocoremanagement\__init__.py", line 330, in execute
    django.setup()
  File "C:UserslislisAppDataLocalProgramsPythonPython35-32libsite-packagesdjango-2.0-py3.5.eggdjango\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "C:UserslislisAppDataLocalProgramsPythonPython35-32libsite-packagesdjango-2.0-py3.5.eggdjangoapps
egistry.py", line 112, in populate
    app_config.import_models()
  File "C:UserslislisAppDataLocalProgramsPythonPython35-32libsite-packagesdjango-2.0-py3.5.eggdjangoappsconfig.py", line 198, in import_models
    self.models_module = import_module(models_module_name)
  File "C:UserslislisAppDataLocalProgramsPythonPython35-32libimportlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 665, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "C:UserslislisDjangomon_sitelogmodels.py", line 6, in <module>
    class Article(models.Model):
  File "C:UserslislisDjangomon_sitelogmodels.py", line 16, in Article
    categorie = models.ForeignKey("Categorie")
TypeError: __init__() missing 1 required positional argument: "on_delete"

I"ve seen some similar issues in stackoverflow, but it seems to not be the same problem: __init__() missing 1 required positional argument: 'quantity'

👻 Read also: what is the best laptop for engineering students?

Getting TypeError: __init__() missing 1 required positional argument: "on_delete" when trying to add parent table after child table with entries __del__: Questions

import time
time.sleep(5)   # Delays for 5 seconds. You can also use a float value.

import time
while True:
    print("This prints once a minute.")
    time.sleep(60) # Delay for 1 minute (60 seconds).

from time import sleep
sleep(0.1) # Time in seconds

Getting TypeError: __init__() missing 1 required positional argument: "on_delete" when trying to add parent table after child table with entries __del__: Questions

import os
os.remove("/tmp/<file_name>.txt")

import os
os.unlink("/tmp/<file_name>.txt")

file_to_rem = pathlib.Path("/tmp/<file_name>.txt")
file_to_rem.unlink()

#!/usr/bin/python
import os
myfile="/tmp/foo.txt"

## If file exists, delete it ##
if os.path.isfile(myfile):
    os.remove(myfile)
else:    ## Show an error ##
    print("Error: %s file not found" % myfile)

#!/usr/bin/python
import os

## Get input ##
myfile= raw_input("Enter file name to delete: ")

## Try to delete the file ##
try:
    os.remove(myfile)
except OSError as e:  ## if failed, report it back to the user ##
    print ("Error: %s - %s." % (e.filename, e.strerror))

Enter file name to delete : demo.txt
Error: demo.txt - No such file or directory.

Enter file name to delete : rrr.txt
Error: rrr.txt - Operation not permitted.

Enter file name to delete : foo.txt

shutil.rmtree()

#!/usr/bin/python
import os
import sys
import shutil

# Get directory name
mydir= raw_input("Enter directory name: ")

## Try to remove tree; if failed show an error using try...except on screen
try:
    shutil.rmtree(mydir)
except OSError as e:
    print ("Error: %s - %s." % (e.filename, e.strerror))

a = [1, 2, 3, 4]
b = a.index(6)

del a[b]
print(a)

Traceback (most recent call last):
  File "D:zjm_codea.py", line 6, in <module>
    b = a.index(6)
ValueError: list.index(x): x not in list

a = [1, 2, 3, 4]

try:
    b = a.index(6)
    del a[b]
except:
    pass

print(a)

>>> a = ["a", "b", "c", "d"]
>>> a.remove("b")
>>> print(a)
["a", "c", "d"]

>>> a = [10, 20, 30, 40, 20, 30, 40, 20, 70, 20]
>>> a = [x for x in a if x != 20]
>>> print(a)
[10, 30, 40, 30, 40, 70]

We hope this article has helped you to resolve the problem. Apart from Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries, check other __del__-related topics.

Want to excel in Python? See our review of the best Python online courses 2023. If you are interested in Data Science, check also how to learn programming in R.

By the way, this material is also available in other languages:

• Italiano Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• Deutsch Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• Français Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• Español Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• Türk Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• Русский Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• Português Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• Polski Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• Nederlandse Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• 中文 Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• 한국어 Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• 日本語 Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries
• हिन्दी Getting TypeError: __init__() missing 1 required positional argument: “on_delete” when trying to add parent table after child table with entries