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Django -- Models don't exist, but Django still loads them

Im getting a ProgrammingError when I try to delete a User object, this is wherever User.delete occurs, it even happens in the admin.
The Error
Django apparently 'thinks' that there's a relationship between auth_user and apiHandlers_cardholders which doesn't exist anywhere, the database doesn't have a column for this, and there is no models.[y nor admin.py in the app named apiHandlers , but Django expects it to, there is even a section of the Admin site devoted to it. This only started happening when I migrated from SQLite to PostGreSQL.
At the moment all the local dependencies (models, admin, forms and fields) are in an app called helpers, I'm not sure if this is efficient, but it keeps everything in one place and avoids complications.
UPDATE 0.1
No. One of the probably gonna be many updates
I used to have a problem when migrating, related to Django Rest Framework, but I eventually managed to fix it by a quick pip install to a new update of restframework, it's no longer giving me any error while making migrations and migrating.
Below is the current traceback I'm getting from the Django admin, it's basically the same in the other deletion methods.
`
Environment:
Request Method: GET
Request URL: http://localhost:8000/admin/auth/user/3/delete/
Django Version: 1.9.2
Python Version: 2.7.10
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'rest_framework',
'corsheaders',
'oauth2_provider',
'apiHandlers',
'frontEnd',
'helpers',
'nonUser']
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.auth.middleware.SessionAuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
'corsheaders.middleware.CorsMiddleware',
'oauth2_provider.middleware.OAuth2TokenMiddleware']
Traceback:
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
149. response = self.process_exception_by_middleware(e, request)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
147. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/contrib/admin/options.py" in wrapper
541. return self.admin_site.admin_view(view)(*args, **kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
149. response = view_func(request, *args, **kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
57. response = view_func(request, *args, **kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/contrib/admin/sites.py" in inner
244. return view(request, *args, **kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapper
67. return bound_func(*args, **kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
149. response = view_func(request, *args, **kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/utils/decorators.py" in bound_func
63. return func.__get__(self, type(self))(*args2, **kwargs2)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/utils/decorators.py" in inner
184. return func(*args, **kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/contrib/admin/options.py" in delete_view
1629. [obj], opts, request.user, self.admin_site, using)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/contrib/admin/utils.py" in get_deleted_objects
128. collector.collect(objs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/contrib/admin/utils.py" in collect
193. return super(NestedObjects, self).collect(objs, source_attr=source_attr, **kwargs)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/models/deletion.py" in collect
230. elif sub_objs:
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/models/query.py" in __nonzero__
266. return type(self).__bool__(self)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/models/query.py" in __bool__
262. self._fetch_all()
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/models/query.py" in _fetch_all
1074. self._result_cache = list(self.iterator())
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/models/query.py" in __iter__
52. results = compiler.execute_sql()
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in execute_sql
848. cursor.execute(sql, params)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
79. return super(CursorDebugWrapper, self).execute(sql, params)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
64. return self.cursor.execute(sql, params)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/utils.py" in __exit__
95. six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/Users/Mason/Documents/dev/FlowFrameWork/flow-framework/env/lib/python2.7/site-packages/django/db/backends/utils.py" in execute
64. return self.cursor.execute(sql, params)
Exception Type: ProgrammingError at /admin/auth/user/3/delete/
Exception Value: relation "apiHandlers_cardholder" does not exist
LINE 1: ...user"."is_active", "auth_user"."date_joined" FROM "apiHandle...
^
`
UPDATE 0.2
I am using ./manage.py runserver (Mac) to run it, so far I haven't managed to test it with Nginx and WSGI on my server.
I am not getting a warning saying that it could affect another model, in the admin, for example, I am just getting this error immediately.

This is very likely to be because you have a stray models.pyc file somewhere. Clear out all the *.pyc files. You can try something like this if you are on linux:
find . -name '*pyc' -exec 'rm' '{}' ';'
Follow that by ./manage.py makemigrations apihandlers and then ./manage.py migrate

Django image upload to Amazon S3 fails with boto

I have been struggling for a while trying to make media file uploads to Amazon S3 from Django work, and would be very thankful if anyone could help.
My app uploads image files without issues locally with a Sqlite3 database as well as Postgres, but when I try to upload my media files to S3, I get the following 500 error:
cannot concatenate 'str' and 'NoneType' objects
Update November 29th
It seems boto cannot find my bucket name, even if it is set in my settings. The 'NoneType' above comes from the following, which is from connection.py and bucket.py:
bucket: None
I have installed django-storages and boto, like described in the following articles:
Using Amazon S3 to Store your Django Site's Static and Media Files
Django-Storages and Amazon S3
Using AWS S3 to Store Static Assets and File Uploads
I tested uploading my media files to my bucket on S3 manually, and the database instances that I created locally links to correct media files from my bucket. From my point of view, the issue occurs when my django view tries to upload the image to S3 via boto (DEFAULT_FILE_STORAGE in my local_settings.py).
The following is in my local_settings.py:
INSTALLED_APPS = (
...
'storages',
)
# Local postgres database
DATABASES = {
"default": {
"ENGINE": "django.db.backends.postgresql_psycopg2",
"NAME": "name",
"USER": "username",
"PASSWORD": "pw",
"PORT": "5432",
}
}
STATICFILES_STORAGE = 'whitenoise.django.GzipManifestStaticFilesStorage'
AWS_QUERYSTRING_AUTH = False
AWS_ACCESS_KEY_ID = 'my-key'
AWS_SECRET_ACCESS_KEY = 'my-key2'
AWS_STORAGE_BUCKET_NAME = 'my-bucket-name'
MEDIAFILES_LOCATION = 'media'
MEDIA_URL = 'http://%s.s3.amazonaws.com/media/' % AWS_STORAGE_BUCKET_NAME
DEFAULT_FILE_STORAGE = "storages.backends.s3boto.S3BotoStorage"
In my upload form in views.py I use something like:
photo = form.cleaned_data['photo']
...
recipe = Recipe(title=title, ..., photo=photo)
recipe.save()
I also tried adding a s3utils.py file like described in 2. Bucket policy and CORS is added like described in above articles. I granted "Everyone" access to upload/delete.
My requirements.txt contains:
Django==1.7.8
Pillow==2.6.1
awscli==1.7.36
boto==2.38.0
botocore==1.0.1
django-storages==1.1.8
whitenoise==1.0.6
...
I use Heroku for my app, and will need to store and host media files from S3.
Does anyone see what I am missing? Let me know if you need more details.
Thanks a lot in advance!
Traceback
Environment:
Request Method: POST
Request URL: http://127.0.0.1:5000/add/
Django Version: 1.7.8
Python Version: 2.7.10
Installed Applications:
('django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django.contrib.admindocs',
'matboken_app',
'crispy_forms',
'PIL',
'django_summernote',
'djangoratings',
'imagekit',
'storages',
's3direct')
Installed Middleware:
('django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.middleware.locale.LocaleMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware')
Traceback:
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
111. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/contrib/auth/decorators.py" in _wrapped_view
21. return view_func(request, *args, **kwargs)
File "/Users/Kenneth/Dropbox/matboken/matboken_app/views.py" in addRecipe
678. recipe.save()
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/base.py" in save
589. force_update=force_update, update_fields=update_fields)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/base.py" in save_base
617. updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/base.py" in _save_table
698. result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/base.py" in _do_insert
731. using=using, raw=raw)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/manager.py" in manager_method
92. return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/query.py" in _insert
921. return query.get_compiler(using=using).execute_sql(return_id)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in execute_sql
920. for sql, params in self.as_sql():
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in as_sql
878. for obj in self.query.objs
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/fields/files.py" in pre_save
301. file.save(file.name, file, save=False)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/db/models/fields/files.py" in save
89. self.name = self.storage.save(name, content)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/django/core/files/storage.py" in save
51. name = self._save(name, content)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/storages/backends/s3boto.py" in _save
385. key = self.bucket.get_key(encoded_name)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/boto/s3/bucket.py" in get_key
192. key, resp = self._get_key_internal(key_name, headers, query_args_l)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/boto/s3/bucket.py" in _get_key_internal
199. query_args=query_args)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/boto/s3/connection.py" in make_request
652. auth_path = self.calling_format.build_auth_path(bucket, key)
File "/Users/Kenneth/Dropbox/matboken/env_1.8/lib/python2.7/site-packages/boto/s3/connection.py" in build_auth_path
94. path = '/' + bucket
Exception Type: TypeError at /add/
Exception Value: cannot concatenate 'str' and 'NoneType' objects

django 1.7 admin: 'ModelMultipleChoiceField' object has no attribute 'limit_choices_to'

I'm working on a legacy django 1.4 project, porting it to django 1.7.
When accessing the django admin interface, in order to show user data I get the aforementioned error.
Environment:
Request Method: GET
Request URL: http://localhost:8000/admin/auth/user/1/
Django Version: 1.7.4
Python Version: 2.7.8
Installed Applications:
('django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django.contrib.admin',
'django.contrib.humanize',
'simple_autocomplete',
'paypal.standard.ipn',
'sorl.thumbnail',
'haystack',
'crispy_forms',
'siteprefs',
'sitegate',
'debug_toolbar',
'modeltranslation',
'rosetta',
# omitted: some project-specific apps
)
Installed Middleware:
('debug_toolbar.middleware.DebugToolbarMiddleware',
'django.middleware.locale.LocaleMiddleware',
'django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware')
Traceback:
File "MYENV/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
111. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "MYENV/lib/python2.7/site-packages/django/contrib/admin/options.py" in wrapper
583. return self.admin_site.admin_view(view)(*args, **kwargs)
File "MYENV/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
105. response = view_func(request, *args, **kwargs)
File "MYENV/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
52. response = view_func(request, *args, **kwargs)
File "MYENV/lib/python2.7/site-packages/django/contrib/admin/sites.py" in inner
206. return view(request, *args, **kwargs)
File "MYENV/lib/python2.7/site-packages/django/contrib/admin/options.py" in change_view
1456. return self.changeform_view(request, object_id, form_url, extra_context)
File "MYENV/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapper
29. return bound_func(*args, **kwargs)
File "MYENV/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
105. response = view_func(request, *args, **kwargs)
File "MYENV/lib/python2.7/site-packages/django/utils/decorators.py" in bound_func
25. return func.__get__(self, type(self))(*args2, **kwargs2)
File "MYENV/lib/python2.7/site-packages/django/db/transaction.py" in inner
394. return func(*args, **kwargs)
File "MYENV/lib/python2.7/site-packages/django/contrib/admin/options.py" in changeform_view
1419. form = ModelForm(instance=obj)
File "MYENV/lib/python2.7/site-packages/django/contrib/auth/forms.py" in __init__
145. super(UserChangeForm, self).__init__(*args, **kwargs)
File "MYENV/lib/python2.7/site-packages/django/forms/models.py" in __init__
333. limit_choices_to = formfield.get_limit_choices_to()
File "MYENV/lib/python2.7/site-packages/django/forms/models.py" in get_limit_choices_to
1126. if callable(self.limit_choices_to):
Exception Type: AttributeError at /admin/auth/user/1/
Exception Value: 'ModelMultipleChoiceField' object has no attribute 'limit_choices_to'
The self object in the offending line is a django.forms.models.ModelMultipleChoiceField instance (of course), the formfield in line 333 (see traceback) is instantiated as formfield = self.fields['groups'].
The error raises even on an empty db (with just one user). I've checked twice but there are no changes in the AUTH_MODEL, in the signals or any OneToOne link to the User model.
I've checked also the external apps for similar issues without any luck. Does anybody had the same issue in the past and can give me an hint on where to search for the source of this error? I'm still reluctant to report a bug to django since I cannot replicate it if I'm unable to define where the error is triggered.
EDIT:
I've verified that the problem arises in every model that has a foreign key (or a M2M, or a O2O). #Alasdair comment was a good suggestion but for sure I do not alter the queryset in all the models so the reason should be elsewhere.

I suggest you try disabling simple_autocomplete. There appears to be a similar issue with django-ajax-selects.

Error in import FloatField, using django-import-export

I am using django-import-export for import csv file. I have a FloatField in my model :
models.py
purchase_price = models.FloatField(null=True, blank=True)
When I import csv file with blank value, it throws an error :
ValueError at /admin/csv_imp/book/process_import/
could not convert string to float:
Request Method: POST
Request URL: http://localhost:8000/admin/csv_imp/book/process_import/
Django Version: 1.7.1
Exception Type: ValueError
Exception Value:
could not convert string to float:
Exception Location: /home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py in get_prep_value, line 1550
Python Executable: /home/bgdev/Desktop/virtualenvs/django17/bin/python
Python Version: 2.7.6
Python Path:
['/home/bgdev/Desktop/virtualenvs/django17/test_pro',
'/home/bgdev/Desktop/virtualenvs/django17/src/admin-bootstrap',
'/home/bgdev/Desktop/virtualenvs/django17/lib/python2.7',
'/home/bgdev/Desktop/virtualenvs/django17/lib/python2.7/plat-i386-linux-gnu',
'/home/bgdev/Desktop/virtualenvs/django17/lib/python2.7/lib-tk',
'/home/bgdev/Desktop/virtualenvs/django17/lib/python2.7/lib-old',
'/home/bgdev/Desktop/virtualenvs/django17/lib/python2.7/lib-dynload',
'/usr/lib/python2.7',
'/usr/lib/python2.7/plat-i386-linux-gnu',
'/usr/lib/python2.7/lib-tk',
'/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages',
'/home/bgdev/Desktop/virtualenvs/django17/lib/python2.7/site-packages']
Server time: Tue, 9 Dec 2014 05:33:36 +0000
Environment:
Request Method: POST
Request URL: http://localhost:8000/admin/csv_imp/book/process_import/
Django Version: 1.7.1
Python Version: 2.7.6
Installed Applications:
('bootstrap_admin',
'import_export',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'csv_imp')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware')
Traceback:
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
111. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
105. response = view_func(request, *args, **kwargs)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
52. response = view_func(request, *args, **kwargs)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/contrib/admin/sites.py" in inner
204. return view(request, *args, **kwargs)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/import_export/admin.py" in process_import
130. raise_errors=True)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/import_export/resources.py" in import_data
359. six.reraise(*sys.exc_info())
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/import_export/resources.py" in import_data
345. self.save_instance(instance, real_dry_run)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/import_export/resources.py" in save_instance
163. instance.save()
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/base.py" in save
591. force_update=force_update, update_fields=update_fields)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/base.py" in save_base
619. updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/base.py" in _save_table
681. forced_update)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/base.py" in _do_update
725. return filtered._update(values) > 0
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/query.py" in _update
600. return query.get_compiler(self.db).execute_sql(CURSOR)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in execute_sql
1004. cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in execute_sql
775. sql, params = self.as_sql()
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in as_sql
969. val = field.get_db_prep_save(val, connection=self.connection)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py" in get_db_prep_save
627. prepared=False)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py" in get_db_prep_value
619. value = self.get_prep_value(value)
File "/home/bgdev/Desktop/virtualenvs/django17/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py" in get_prep_value
1550. return float(value)
Exception Type: ValueError at /admin/csv_imp/book/process_import/
Exception Value: could not convert string to float:

I found similar issue with and IntegerField. Being the last column in the csv file, it turns out that I was introducing an extra End of Line character in the dataset, even if the field had an empty value. Removing the EOL character from every line before adding it to the dataset fixed the issue:
for line in file.readlines():
line = line.rstrip('\r\n')
dataset.append(tuple(item for item in line.split(',')))

This link will show you what null and blank do: differentiate null=True, blank=True in django
If you can arrange your csv file to have all of the null values at the end, you can just remove the commas. That might work. Or perhaps create a temporary model that assigns those fields to a Charfield. Then copy appropriate fields to your final model
This is untested:
update <table> set <field> = 0 where id in (select id from <table> where <field> = "");
Fill in your table name and the field name as appropriate. You can run this from your sql command line program

Uploading to Google Cloud Storage from Django on App Engine

I'm using Django 1.5 on Google App Engine and I'm trying to upload files to Google Cloud Storage. I'm using the gcs the library and have written a custom file upload handler that I've registered in settings.py as my only file uploader. I can see my file being correctly uploaded in the blobstore viewer in my development environment but once form.save() is called in views.py I get an exception thrown saying that it's a read only file system? I know Google App Engine doesn't allow access to the file system which is why I'm using GCS in the first place!
Is there something I need to do to stop Django from trying to save the file to disk?
The relevant code is attached in this gist.
Thanks :)
Stack Trace:
Environment:
Request Method: POST
Request URL: http://localhost:8080/cms/media/add
Django Version: 1.5
Python Version: 2.7.5
Installed Applications:
('django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.staticfiles',
'django.contrib.messages',
'api',
'cms',
'frontend')
Installed Middleware:
('django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware')
Traceback:
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/core/handlers/base.py" in get_response
115. response = callback(request, *callback_args, **callback_kwargs)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/contrib/auth/decorators.py" in _wrapped_view
25. return view_func(request, *args, **kwargs)
File "/Users/james/Dropbox/University/Year 4/Advanced Development/assignment/cms/views.py" in media_add_or_edit
44. form.save()
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/forms/models.py" in save
370. fail_message, commit, construct=False)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/forms/models.py" in save_instance
87. instance.save()
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/db/models/base.py" in save
546. force_update=force_update, update_fields=update_fields)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/db/models/base.py" in save_base
650. result = manager._insert([self], fields=fields, return_id=update_pk, using=using, raw=raw)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/db/models/manager.py" in _insert
215. return insert_query(self.model, objs, fields, **kwargs)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/db/models/query.py" in insert_query
1673. return query.get_compiler(using=using).execute_sql(return_id)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/db/models/sql/compiler.py" in execute_sql
936. for sql, params in self.as_sql():
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/db/models/sql/compiler.py" in as_sql
894. for obj in self.query.objs
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/db/models/fields/files.py" in pre_save
250. file.save(file.name, file, save=False)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/db/models/fields/files.py" in save
86. self.name = self.storage.save(name, content)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/core/files/storage.py" in save
48. name = self._save(name, content)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/django-1.5/django/core/files/storage.py" in _save
198. fd = os.open(full_path, flags, 0o666)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/tools/devappserver2/python/stubs.py" in fake_open
71. raise OSError(errno.EROFS, 'Read-only file system', filename)
Exception Type: OSError at /cms/media/add
Exception Value: [Errno 30] Read-only file system: u'/Users/james/Dropbox/University/Year 4/Advanced Development/assignment/IMG_0746.jpg'

I eventually solved this by moving the FileField from my Model into my ModelForm like so:
# Used for uploading media that forms part of a story
class Media(models.Model):
title = models.CharField(max_length=100)
type = models.CharField(max_length=5, choices=MEDIA_TYPES)
content = models.TextField()
date_created = models.DateTimeField(auto_now_add=True)
# Used to convert the media model to a form in the cms
class MediaForm(forms.ModelForm):
file = forms.FileField()
class Meta:
model = Media
# Don't show the date created field because we want that to be set automatically
exclude = ('date_created', 'content',)
I'm sure I tried that before but it appears to have fixed my issue, hopefully this might help someone else who runs into the same problem.