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Django: Error when calling the metaclass bases

Here is the error

TypeError: Error when calling the metaclass bases metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases

The class in question within my models.py

class Business(models.Model, forms.Form):
    name = models.CharField(max_length=128)
    tel_no = models.CharField(max_length=11)
    address_ln1 = models.CharField(max_length=128)
    address_ln2 = models.CharField(max_length=128)
    city = models.CharField(max_length=64)
    county = GBCountySelect()
    postcode = GBPostcodeField()
    website = models.URLField(max_length=128)
# Logging Info
    slug = models.SlugField()
    date_added = models.DateField(auto_now_add=True)
    time_added = models.TimeField()
    added_by_user = models.CharField(max_length=64)
    last_edit_time = models.TimeField(auto_now=True)
    last_edit_date = models.DateField(auto_now=True)

The line I am getting the error on:

name = models.CharField(max_length=128)

But I (think) it means this one:

class Business(models.Model, forms.Form):

I'm not sure what it means exactly, how can I inherit my models from models.Model and forms.Form within the same class? Can I not pass two values when creating my class? If so how?

ANOTHER EDIT

All my imports
from django.db import models
from django import forms
from django.contrib.localflavor import generic
from django.contrib.localflavor.gb.forms import GBPostcodeField, GBCountySelect

Full traceback:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/core/management/__init__.py", line 443, in execute_from_command_line
    utility.execute()
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/core/management/__init__.py", line 382, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/core/management/base.py", line 196, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/core/management/base.py", line 231, in execute
    self.validate()
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/core/management/base.py", line 266, in validate
    num_errors = get_validation_errors(s, app)
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/core/management/validation.py", line 30, in get_validation_errors
    for (app_name, error) in get_app_errors().items():
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/db/models/loading.py", line 158, in get_app_errors
    self._populate()
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/db/models/loading.py", line 64, in _populate
    self.load_app(app_name, True)
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/db/models/loading.py", line 88, in load_app
    models = import_module('.models', app_name)
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/home/jws1000/envs/glutenfree/glutenfree/glutenfree/listings/models.py", line 9, in <module>
    class Business(models.Model, forms.Form):
  File "/home/jws1000/.virtualenvs/glutenfree/lib/python2.7/site-packages/django/db/models/base.py", line 41, in __new__
    new_class = super_new(cls, name, bases, {'__module__': module})
TypeError: Error when calling the metaclass bases
    metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases
like image 514
jdx Avatar asked Jul 25 '12 19:07

jdx


1 Answers

This is the problem:

class Business(models.Model, forms.Form):

You're trying to inherit from Model and Form. You can't, and you shouldn't.

You can't because the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases. Form has a metaclass:

__metaclass__ = DeclarativeFieldsMetaclass

Model also has a metaclass:

__metaclass__ = ModelBase

If you were to do this, you would need to set a metaclass which derives from both of those.

However, you shouldn't do this, because django has ModelForms, which exist to create forms that model models, saving you the trouble of the complexity here. Just stop inheriting from Form.

like image 153
Marcin Avatar answered Sep 21 '22 20:09

Marcin