There is such a system of models

class NormalTag(models.Model): caption = models.CharField(max_length=1024, unique=True, blank=False, default=None) def __init__(self, caption): super().__init__() self.caption = caption def __str__(self): return self.caption class Tag(models.Model): caption = models.CharField(max_length=1024) def __init__(self, caption): super().__init__() self.caption = caption self.set_normaltag() def normalize(self): return self.caption.lower().replace(" ",'').replace("\"",'') def set_normaltag(self): try: normaltag = self.get_normaltag() except NormalTag.DoesNotExist: normaltag = NormalTag(self.normalize()) normaltag.save() def get_normaltag(self): return NormalTag.objects.get(caption=self.normalize()) def __str__(self): return self.caption

When calling from the shell, it gives an error:

 [env]user ~/path/to/project > python manage.py shell Python 3.5.2 (default, Jul 5 2016, 12:43:10) [GCC 5.4.0 20160609] on linux Type "help", "copyright", "credits" or "license" for more information. (InteractiveConsole) >>> from home.models import NormalTag, Tag >>> t = Tag("ПроВеРка ТэГа") Traceback (most recent call last): File "<console>", line 1, in <module> File "/home/path/to/project/home/models.py", line 28, in __init__ self.set_normaltag() File "/home/path/to/project/home/models.py", line 35, in set_normaltag normaltag = self.get_normaltag() File "/home/path/to/project/home/models.py", line 41, in get_normaltag return NormalTag.objects.get(caption=self.normalize()) File "/home/path/to/env/lib/python3.5/site-packages/django/db/models/manager.py", line 85, in manager_method return getattr(self.get_queryset(), name)(*args, **kwargs) File "/home/path/to/env/lib/python3.5/site-packages/django/db/models/query.py", line 379, in get num = len(clone) File "/home/path/to/env/lib/python3.5/site-packages/django/db/models/query.py", line 238, in __len__ self._fetch_all() File "/home/path/to/env/lib/python3.5/site-packages/django/db/models/query.py", line 1087, in _fetch_all self._result_cache = list(self.iterator()) File "/home/path/to/env/lib/python3.5/site-packages/django/db/models/query.py", line 66, in __iter__ obj = model_cls.from_db(db, init_list, row[model_fields_start:model_fields_end]) File "/home/path/to/env/lib/python3.5/site-packages/django/db/models/base.py", line 565, in from_db new = cls(*values) TypeError: __init__() takes 2 positional arguments but 3 were given

I did not understand where it comes from.

    2 answers 2

    In janga a lot of things happen magically. That is, in the framework, not everything meets the python, although it is written on it.

    In this case, you passed a positional argument to the model, and when creating models, you need to pass only named arguments.

    In your case, it was necessary to write:

     t = Tag(caption="ПроВеРка ТэГа")

    And yes, in models it is necessary to override the __init__ method with caution, if you need to add any additional actions during model creation, it is better to use the model manager’s create() method, it was created specifically for this.

      Models have an overloaded create() method for creating objects. You should not use the designer.

      https://docs.djangoproject.com/en/1.10/ref/models/instances/ - an example is right here.