Django-taggit: add tags

Question

django-taggit==1.2.0

class Post(models.Model):
    tags = TaggableManager() # django-taggit
    ...


    def save(self, *args, **kwargs):
        super().save(*args, **kwargs)
        tag_slugs_list = strip_and_split(self.tags_aux)
        # tmp_tags = ', '.join('"{}"'.format(w) for w in tag_slugs_list)
        tmp_tags = Tag.objects.filter(slug__in=tag_slugs_list)
        self.tags.add(list(tmp_tags))

Problem

Environment:


Request Method: POST
Request URL: http://localhost:8000/admin/posts/post/1/change/

Django Version: 3.0.8
Python Version: 3.8.0
Installed Applications:
['admin_aux',
 'images.apps.ImagesConfig',
 'django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.sites',
 'django.contrib.sitemaps',
 'posts',
 'sidebars',
 'general',
 'categories',
 'marketing',
 'home',
 'authors',
 'taggit',
 'cachalot',
 'widgets',
 'code_samples',
 'hyper_links',
 'polls',
 'applications',
 'videos',
 'quotations',
 'languages',
 'people',
 'arbitrary_htmls.apps.ArbitraryHtmlsConfig',
 'tweets',
 'vk_posts',
 'facebook_posts',
 'instagram_posts',
 'email_subscriptions',
 'social_share',
 'assessments',
 'django_bootstrap_breadcrumbs',
 'promo']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']



Traceback (most recent call last):
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/core/handlers/base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/core/handlers/base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 607, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/utils/decorators.py", line 130, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/views/decorators/cache.py", line 44, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/contrib/admin/sites.py", line 231, in inner
    return view(request, *args, **kwargs)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 1641, in change_view
    return self.changeform_view(request, object_id, form_url, extra_context)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/utils/decorators.py", line 43, in _wrapper
    return bound_method(*args, **kwargs)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/utils/decorators.py", line 130, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 1522, in changeform_view
    return self._changeform_view(request, object_id, form_url, extra_context)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 1565, in _changeform_view
    self.save_model(request, new_object, form, not add)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/django/contrib/admin/options.py", line 1081, in save_model
    obj.save()
  File "/home/michael/PycharmProjects/pcask/pcask/posts/models.py", line 65, in save
    self.tags.add(list(tmp_tags))
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/taggit/utils.py", line 124, in inner
    return func(self, *args, **kwargs)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/taggit/managers.py", line 130, in add
    tag_objs = self._to_tag_model_instances(tags)
  File "/home/michael/PycharmProjects/pcask/venv/lib/python3.8/site-packages/taggit/managers.py", line 184, in _to_tag_model_instances
    raise ValueError(

Exception Type: ValueError at /admin/posts/post/1/change/
Exception Value: Cannot add [<Tag: Linux>, <Tag: OS>] (<class 'list'>). Expected <class 'django.db.models.base.ModelBase'> or str.

How can I cope with this?

Answer 1

You need to unpack the Tag objects, for example with iterable unpacking:

    def save(self, *args, **kwargs):
        super().save(*args, **kwargs)
        tag_slugs_list = strip_and_split(self.tags_aux)
        tmp_tags = Tag.objects.filter(slug__in=tag_slugs_list)
        # iterable unpacking
        self.tags.add()

Here the asterisk in front of tmp_tags will unpack the iterable in separate elements.

If these are tag names however, the django-taggit manager however also accepts strings, so you can implement this as:

    def save(self, *args, **kwargs):
        super().save(*args, **kwargs)
        tag_slugs_list = strip_and_split(self.tags_aux)
        self.tags.add()

Here it will create new tags for names that do not yet exist.