Error when testing the view with a file upload - django

Question

I would like to test a file upload from my view with the following function:
def test_post(self):
with open("path/to/myfile/test_file.txt") as file:
post_data = {
'description': "Some important file",
'file': file,
}
response = self.client.post(self.test_url, post_data)
self.assertEqual(response.status_code, 302)
document = Document.objects.first()
self.assertEqual(document.description, "My File")
self.assertEqual(document.filename, 'test_file.txt')
When I test the file upload on the actual website, it works. But when I run this test, I get the following error:
django.core.exceptions.SuspiciousFileOperation: Storage can not find
an available filename for "WHJpMYuGGCMdSKFruieo/Documents/eWEjGvEojETTghSVCijsaCINZVxTvzpXNRBvmpjOrYvKAKCjYu/test_file_KTEMuQa.txt".
Please make sure that the corresponding file field allows sufficient
"max_length".
Here is my form save method:
def save(self, commit=True):
instance = super(DocumentForm, self).save(commit=False)
instance.filename = self.cleaned_data['file'].name
if commit:
instance.save() # error occurs here
return instance
Seeing as it works on the actual website, I suspect it has something to do with the way I setup the file in the test; probably something small.

Answer 1

For the sake of brevity, I had removed irrelevant model fields from my original question. But when Ahtisham requested to see the upload_to attribute (which had a custom function), I removed those irrelevant fields and it worked!
So this is my original code (which didn't work) with the irrelevant fields:
def documents_path(instance, filename):
grant = instance.grant
client = grant.client
return '{0}/Grant Documents/{1}/{2}'.format(client.folder_name, grant.name, filename)
....
file = models.FileField(upload_to=documents_path)
But this works:
def documents_path(instance, filename):
return 'Documents/{0}'.format(filename)
The reason why it worked on the actual website is because it wasn't using long characters from the test fixtures. Seems like those fields that I thought were irrelevant for the question were actually quite important!
TL;DR I decreased the length of the custom document path.

Answer 2

I had the same error with an ImageField. The solution was adding max_length=255 in models.py:
image = models.ImageField(upload_to=user_path, max_length=255)
Then running python manage.py makemigrations and python manage.py migrate.