Python-django typeerror: expected string or bytes-like object error -- object.save()

Question

I'm learning django-orm my code is this:

from django.db import models
# Create your models here.
class Author(models.Model):
    def __str__(self):
        return self.name
    name = models.CharField(max_length=50)
    created = models.DateTimeField() 
class Book(models.Model):
    def __str__(self):
        return self.name
    name = models.CharField(max_length=50) 
    created = models.DateTimeField()
    
    author = models.ForeignKey(Author, on_delete = models.CASCADE) 
    price = models.DecimalField(decimal_places=2, max_digits=4, null=True)

and I'm creating a shell then I'm instantiation objects like this:

python manage.py shell
   >> from books.models import Author,Book 
   >> Author.objects.all()
   >> from django.utils import timezone
   >> author = Author(name="Victor Hugo",created = timezone.now) 
   >> author.save()

But when i try to .save() my objects it's giving this error:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\base.py", line 740, in save     
    self.save_base(using=using, force_insert=force_insert,
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\base.py", line 777, in save_base
    updated = self._save_table(
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\base.py", line 870, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\base.py", line 907, in _do_insert
    return manager._insert([self], fields=fields, return_id=update_pk,
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\query.py", line 1186, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\sql\compiler.py", line 1334, in execute_sql
    for sql, params in self.as_sql():
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\sql\compiler.py", line 1276, in as_sql
    value_rows = [
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\sql\compiler.py", line 1277, in <listcomp>
    [self.prepare_value(field, self.pre_save_val(field, obj)) for field in fields]
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\sql\compiler.py", line 1277, in <listcomp>
    [self.prepare_value(field, self.pre_save_val(field, obj)) for field in fields]
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\sql\compiler.py", line 1218, in prepare_value
    value = field.get_db_prep_save(value, connection=self.connection)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\fields\__init__.py", line 789, in get_db_prep_save
    return self.get_db_prep_value(value, connection=connection, prepared=False)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\fields\__init__.py", line 1431, in get_db_prep_value
    value = self.get_prep_value(value)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\fields\__init__.py", line 1410, in get_prep_value
    value = super().get_prep_value(value)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\fields\__init__.py", line 1270, in get_prep_value
    return self.to_python(value)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\fields\__init__.py", line 1371, in to_python
    parsed = parse_datetime(value)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\utils\dateparse.py", line 106, in parse_datetime
    match = datetime_re.match(value)
TypeError: expected string or bytes-like object

Any help? What I'm supposed to do? I'm pretty new here and this is my first question

Answer 1

The issue is depicted on this line of the error message:

  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\db\models\fields\__init__.py", line 1371, in to_python
    parsed = parse_datetime(value)
  File "C:\Users\Casper\AppData\Local\Programs\Python\Python38\lib\site-packages\django\utils\dateparse.py", line 106, in parse_datetime
    match = datetime_re.match(value)
  TypeError: expected string or bytes-like object

It indicates that your field for your datetime (when you created an Author object with timezone.now) was invalid.

This is because you didn't call it correctly. Your shell should show this:

python manage.py shell
   >> from books.models import Author,Book 
   >> Author.objects.all()
   >> from django.utils import timezone
   >> author = Author(name="Victor Hugo",created = timezone.now()) 
   >> author.save()

Notice the change in timezone.now to timezone.now().

Here's a link to the reasoning behind the answer.