Fix NoArtifactContentUploadViewSet when no file is provided

[quba42]

Needed for pulp/pulp_deb#1018

Without it I get:

pulp [29bce454246341c5bd3433e6573650d0]: django.request:ERROR: Internal Server Error: /pulp/api/v3/content/deb/release_components/
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python3.8/site-packages/django/views/decorators/csrf.py", line 56, in wrapper_view
    return view_func(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/rest_framework/viewsets.py", line 125, in view
    return self.dispatch(request, *args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/rest_framework/views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "/usr/local/lib/python3.8/site-packages/rest_framework/views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/usr/local/lib/python3.8/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
    raise exc
  File "/usr/local/lib/python3.8/site-packages/rest_framework/views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "/src/pulpcore/pulpcore/plugin/viewsets/content.py", line 49, in create
    temp_file.save()
  File "/src/pulpcore/pulpcore/app/models/content.py", line 152, in save
    super().save(*args, **kwargs)
  File "/usr/lib64/python3.8/contextlib.py", line 75, in inner
    return func(*args, **kwds)
  File "/usr/local/lib/python3.8/site-packages/django_lifecycle/mixins.py", line 192, in save
    save(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/django/db/models/base.py", line 814, in save
    self.save_base(
  File "/usr/local/lib/python3.8/site-packages/django/db/models/base.py", line 877, in save_base
    updated = self._save_table(
  File "/usr/local/lib/python3.8/site-packages/django/db/models/base.py", line 1020, in _save_table
    results = self._do_insert(
  File "/usr/local/lib/python3.8/site-packages/django/db/models/base.py", line 1061, in _do_insert
    return manager._insert(
  File "/usr/local/lib/python3.8/site-packages/django/db/models/manager.py", line 87, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/django/db/models/query.py", line 1805, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
  File "/usr/local/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1821, in execute_sql
    for sql, params in self.as_sql():
  File "/usr/local/lib/python3.8/site-packages/django_readonly_field/compiler.py", line 31, in as_sql
    return super(ReadonlySQLCompilerMixin, self).as_sql()
  File "/usr/local/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1745, in as_sql
    value_rows = [
  File "/usr/local/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1746, in <listcomp>
    [
  File "/usr/local/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1747, in <listcomp>
    self.prepare_value(field, self.pre_save_val(field, obj))
  File "/usr/local/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1695, in pre_save_val
    return field.pre_save(obj, add=True)
  File "/src/pulpcore/pulpcore/app/models/fields.py", line 72, in pre_save
    is_in_artifact_storage = file.name.startswith(os.path.join(settings.MEDIA_ROOT, "artifact"))
AttributeError: 'NoneType' object has no attribute 'startswith'

[mdellweg]

Interesting. The assumption has always been, that you still uploaded a file even if it did not turn in to an artifact in the end.
That's why the toolset is called NoArtifactContent*UPLOAD*Something.
Does the retrieve logic warrant for an additional step in the class hierarchy?

[quba42]

Does the retrieve logic warrant for an additional step in the class hierarchy?

That is an option, and would mirror what I am using on the serializer side. I have created an issue #5086 to go with this draft PR, that details the option.

[quba42]

Closed in favor of #5088