Custom validation Django admin unknown field - django

Question

I am trying to make a custom validation for the imageField in the admin panel, but I get the following error. There is nog field with the namen banner_image in the Event model class, but when I change field = ('banner_image',) to something else I get instead of "specified for Event" specified for EventBanner. most solutions I find for making a custom validation are for older versions of Django.
django.core.exceptions.FieldError: Unknown field(s) (banner_image) specified for Event. Check fields/fieldsets/exclude attributes of class EventAdmin.
app admin.py:
class BannerImageForm(forms.ModelForm):
class Meta:
model = EventBanner
fields = ['banner_image',]
def clean_banner_image(self):
banner_image = self.cleaned_data['banner_image']
if not banner_image:
raise forms.ValidationError("No image!")
else:
w, h = get_image_dimensions(banner_image)
if w != 1200:
raise forms.ValidationError("The image is %i pixel wide. It's supposed to be 1200px" % w)
if h != 200:
raise forms.ValidationError("The image is %i pixel high. It's supposed to be 200px" % h)
return banner_image
class EventAdmin(admin.ModelAdmin):
form = BannerImageForm
list_display = ('event_name', 'event_start_date')
formfield_overrides={
models.TextField:{'widget':Textarea(attrs={'rows':15, 'cols':80})}
}
admin.site.register(Event, EventAdmin)
app models.py:
class EventBanner(models.Model):
event = models.OneToOneField(Event, unique=True)
banner_image = models.ImageField(upload_to=get_image_path, blank=True, null=True)
def clean(self):
validate_only_one_instance(self)
TraceBack:
Environment:
Request Method: GET
Request URL: http://localhost:8000/admin/events/event/1/change/
Django Version: 1.10.4
Python Version: 3.5.2
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'organizations.apps.OrganizationsConfig',
'news.apps.NewsConfig',
'events.apps.EventsConfig',
'bootstrap3',
'django_forms_bootstrap',
'registration']
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',
'django.contrib.auth.middleware.SessionAuthenticationMiddleware']
Traceback:
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/options.py" in get_form
642. return modelform_factory(self.model, **defaults)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/forms/models.py" in modelform_factory
548. return type(form)(class_name, (form,), form_class_attrs)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/forms/models.py" in __new__
257. raise FieldError(message)
During handling of the above exception (Unknown field(s) (banner_image) specified for Event), another exception occurred:
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/core/handlers/exception.py" in inner
39. response = get_response(request)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/core/handlers/base.py" in _get_response
187. response = self.process_exception_by_middleware(e, request)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/core/handlers/base.py" in _get_response
185. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/options.py" in wrapper
544. return self.admin_site.admin_view(view)(*args, **kwargs)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/utils/decorators.py" in _wrapped_view
149. response = view_func(request, *args, **kwargs)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
57. response = view_func(request, *args, **kwargs)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/sites.py" in inner
211. return view(request, *args, **kwargs)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/options.py" in change_view
1512. return self.changeform_view(request, object_id, form_url, extra_context)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/utils/decorators.py" in _wrapper
67. return bound_func(*args, **kwargs)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/utils/decorators.py" in _wrapped_view
149. response = view_func(request, *args, **kwargs)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/utils/decorators.py" in bound_func
63. return func.__get__(self, type(self))(*args2, **kwargs2)
File "/usr/lib/python3.5/contextlib.py" in inner
30. return func(*args, **kwds)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/options.py" in changeform_view
1438. ModelForm = self.get_form(request, obj)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/options.py" in get_form
608. fields = flatten_fieldsets(self.get_fieldsets(request, obj))
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/options.py" in get_fieldsets
298. return [(None, {'fields': self.get_fields(request, obj)})]
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/options.py" in get_fields
597. form = self.get_form(request, obj, fields=None)
File "/home/dave/Projecten/Web/Django/venv/lib/python3.5/site-packages/django/contrib/admin/options.py" in get_form
646. % (e, self.__class__.__name__)
Exception Type: FieldError at /admin/events/event/1/change/
Exception Value: Unknown field(s) (banner_image) specified for Event. Check fields/fieldsets/exclude attributes of class EventAdmin.

Answer 1

The form for EventAdmin must use the Event model. You get the error because BannerImageForm form uses the EventBanner model.
Create an EventBannerAdmin, and get your code working with that. Then, you could change it to an inline, and include the inline in the EventAdmin.