Django migrations and FileSystemStorage depending on settings

Question

In my Django app I use a FileSystemStorage for generated files. I initialize it like this:

import os from urlparse import urljoin  from django.conf import settings from django.core.files.storage import FileSystemStorage  gen_files_storage = FileSystemStorage(location=os.path.join(settings.MEDIA_ROOT, 'generated/'), base_url=urljoin(settings.MEDIA_URL, 'generated/')) 

When I want to create a new file I use:

from django.core.files.base import ContentFile from django.db import models  def next_number():     # num = ...     return num  gen_file = models.FileField(storage=gen_files_storage) gen_file.save('file%s.txt' % next_number(), ContentFile('')) 

That works fine. The only problem is that the FileSystemStorage's path is "hardcoded" in the Django migration. Because I use different settings for development (which changes) and production, often the manage.py makemigrations command generates a migration only because the path changed, although everything stays the same in the database.

I know there is a solution using a subclass of FileSystemStorage (see my answer below), but is there a better solution?

Answer 1

There is a solution involving a custom @deconstructible subclass of FileSystemStorage:

import os from urlparse import urljoin  from django.conf import settings from django.core.files.storage import FileSystemStorage from django.utils.deconstruct import deconstructible  @deconstructible class MyFileSystemStorage(FileSystemStorage):     def __init__(self, subdir):         self.subdir = subdir         super(MyFileSystemStorage, self).__init__(location=os.path.join(settings.MEDIA_ROOT, self.subdir), base_url=urljoin(settings.MEDIA_URL, self.subdir))      def __eq__(self, other):         return self.subdir == other.subdir 

Then I can initialize the storage like this:

import os from urlparse import urljoin  from django.conf import settings from django.core.files.storage import FileSystemStorage  gen_files_storage = MyFileSystemStorage('generated/') 

This way Django migrations won't notice changes in my settings. Is there a better way though?