AttributeError: type object 'Product' has no attribute '_parler_meta' - DJANGO

Question

When attempting to migrate my database in Django. I receive the following:

Running migrations:

Applying shop.0002_transactions...Traceback (most recent call last):
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/parler/models.py", line 942, in contribute_translations
    base = shared_model._parler_meta
AttributeError: type object 'Product' has no attribute '_parler_meta'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/core/management/__init__.py", line 395, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/core/management/base.py", line 328, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/core/management/base.py", line 369, in execute
    output = self.handle(*args, **options)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/core/management/base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/core/management/commands/migrate.py", line 233, in handle
    fake_initial=fake_initial,
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/executor.py", line 117, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/executor.py", line 245, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/migration.py", line 114, in apply
    operation.state_forwards(self.app_label, project_state)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/operations/models.py", line 86, in state_forwards
    list(self.managers),
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/state.py", line 96, in add_model
    self.reload_model(app_label, model_name)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/state.py", line 157, in reload_model
    self._reload(related_models)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/state.py", line 190, in _reload
    self.apps.render_multiple(states_to_be_rendered)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/state.py", line 307, in render_multiple
    model.render(self)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/state.py", line 578, in render
    return type(self.name, bases, body)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/models/base.py", line 320, in __new__
    new_class._meta.apps.register_model(new_class._meta.app_label, new_class)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/migrations/state.py", line 338, in register_model
    self.do_pending_operations(model)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/apps/registry.py", line 424, in do_pending_operations
    function(model)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/apps/registry.py", line 403, in apply_next_model
    self.lazy_model_operation(next_function, *more_models)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/apps/registry.py", line 389, in lazy_model_operation
    function()
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/models/fields/related.py", line 317, in resolve_related_class
    field.do_related_class(related, model)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/django/db/models/fields/related.py", line 388, in do_related_class
    self.contribute_to_related_class(other, self.remote_field)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/parler/fields.py", line 58, in contribute_to_related_class
    self.model.contribute_translations(cls)
  File "/Users/itsd/Desktop/Web Projects/Django Projects/e-commerce_shop/env/myshop/lib/python3.7/site-packages/parler/models.py", line 944, in contribute_translations
    raise TypeError("Translatable model {} does not appear to inherit from TranslatableModel".format(shared_model))
TypeError: Translatable model <class '__fake__.Product'> does not appear to inherit from TranslatableModel

I do not understand what the issue is preventing me from migrating the database.

Any help is appreciated.

My models.py file 

from django.db import models
from django.urls import reverse
from parler.models import TranslatableModel, TranslatedFields


class Category(TranslatableModel):
translations = TranslatedFields(
        name = models.CharField(max_length=200, db_index=True),
        slug = models.SlugField(max_length=200, db_index=True, 
unique=True)
    )

class Meta:
    # ordering = ('name',)
    verbose_name = 'category'
    verbose_name_plural = 'categories'

def __str__(self):
    return self.name

def get_absolute_url(self):
        return reverse('shop:product_list_by_category', args=[self.slug])


class Product(TranslatableModel):
translations = TranslatedFields(name = models.CharField(max_length=200, 
db_index=True), slug = models.SlugField(max_length=200, db_index=True), 
description = models.TextField(blank=True))
category = models.ForeignKey(Category, related_name='products', 
on_delete=models.CASCADE)
image = models.ImageField(upload_to='products/%Y/%m/%d', blank=True)

price = models.DecimalField(max_digits=10, decimal_places=2)
available = models.BooleanField(default=True)
created = models.DateTimeField(auto_now_add=True)
updated = models.DateTimeField(auto_now=True)

def __str__(self):
    return self.name

def get_absolute_url(self):
        return reverse('shop:product_detail', args=[self.id, self.slug])

I do not understand what the issue may be. Here is my admin.py also. I believe the disconnect is between these two files after I make migrations and attempt to migrate.

from django.contrib import admin
from .models import Category, Product
from parler.admin import TranslatableAdmin


@admin.register(Category)
class CategoryAdmin(TranslatableAdmin):
list_display = ['name', 'slug']

def get_prepopulated_fields(self, request, obj=None):
        return {'slug': ('name',)}


@admin.register(Product)
class ProductAdmin(TranslatableAdmin):
    list_display = ['name', 'slug', 'price', 'available', 'created', 
'updated']
list_filter = ['available', 'created', 'updated']
list_editable = ['price', 'available']

def get_prepopulated_fields(self, request, obj=None):
        return {'slug': ('name',)}

Answer 1

I think the solution to this problem is in the same book you are working from.

Have you read this and made sure you changed the two occurences, not only one?

Edit the file migrations/0002_translations.py of the shop application and replace the two occurrences of the following line:

Copy bases=(parler.models.TranslatedFieldsModelMixin, models.Model), with the following one:

Copy bases=(parler.models.TranslatableModel, models.Model), This is a fix for a minor issue found in the django-parler version you are using. This change is necessary to prevent the migration from failing when applying it. This issue is related to creating translations for existing fields in the model and will probably be fixed in newer django-parler versions.

Answer 2

As far as I could see, the answer is that "parler" is currently broken. I ran into the same problem as you and even though I also tried to follow the documentation (and NOT the book!) at django-parler.readthedocs.io, the result was a COMPLETELY destroyed set of migrations, which I then had to painfully delete and rebuilt from scratch (always make complete backups BEFORE you do anything that touches migrations!).

I have opened a case with the Django Parler team @GitHub, but I have so far not received any answer. I believe this product is no longer maintained, or they have too many other things to work on.

In the end I ignored anything that used "Django-parler" in the book and jumped to the next section.

Once I will be working on my own product, I will most likely have to try other solutions from djangopackages.org

I know this is not the solution you were looking for, but I believe it is the correct answer, since "parler" simply seems to be broken at this point in time.