This document describes Django’s file access APIs for files such as those\nuploaded by a user. The lower level APIs are general enough that you could use\nthem for other purposes. If you want to handle «static files» (JS, CSS, etc.),\nsee Come gestire file statici (Es. immagini, JavaScript, CSS).
\nBy default, Django stores files locally, using the MEDIA_ROOT and\nMEDIA_URL settings. The examples below assume that you’re using these\ndefaults.
However, Django provides ways to write custom file storage systems that\nallow you to completely customize where and how Django stores files. The\nsecond half of this document describes how these storage systems work.
\nWhen you use a FileField or\nImageField, Django provides a set of APIs you can use\nto deal with that file.
Consider the following model, using an ImageField to\nstore a photo:
from django.db import models\n\n\nclass Car(models.Model):\n name = models.CharField(max_length=255)\n price = models.DecimalField(max_digits=5, decimal_places=2)\n photo = models.ImageField(upload_to="cars")\n specs = models.FileField(upload_to="specs")\nAny Car instance will have a photo attribute that you can use to get at\nthe details of the attached photo:
>>> car = Car.objects.get(name="57 Chevy")\n>>> car.photo\n<ImageFieldFile: cars/chevy.jpg>\n>>> car.photo.name\n'cars/chevy.jpg'\n>>> car.photo.path\n'/media/cars/chevy.jpg'\n>>> car.photo.url\n'https://media.example.com/cars/chevy.jpg'\nThis object – car.photo in the example – is a File object, which means\nit has all the methods and attributes described below.
For example, you can change the file name by setting the file’s\nname to a path relative to the file storage’s\nlocation (MEDIA_ROOT if you are using the default\nFileSystemStorage):
>>> import os\n>>> from django.conf import settings\n>>> initial_path = car.photo.path\n>>> car.photo.name = "cars/chevy_ii.jpg"\n>>> new_path = os.path.join(settings.MEDIA_ROOT, car.photo.name)\n>>> # Move the file on the filesystem\n>>> os.rename(initial_path, new_path)\n>>> car.save()\n>>> car.photo.path\n'/media/cars/chevy_ii.jpg'\n>>> car.photo.path == new_path\nTrue\nTo save an existing file on disk to a FileField:
>>> from pathlib import Path\n>>> from django.core.files import File\n>>> path = Path("/some/external/specs.pdf")\n>>> car = Car.objects.get(name="57 Chevy")\n>>> with path.open(mode="rb") as f:\n... car.specs = File(f, name=path.name)\n... car.save()\n...\nFile objectLink to this heading#Internally, Django uses a django.core.files.File instance any time it\nneeds to represent a file.
Most of the time you’ll use a File that Django’s given you (i.e. a file\nattached to a model as above, or perhaps an uploaded file).
If you need to construct a File yourself, the easiest way is to create one\nusing a Python built-in file object:
>>> from django.core.files import File\n\n# Create a Python file object using open()\n>>> f = open("/path/to/hello.world", "w")\n>>> myfile = File(f)\nNow you can use any of the documented attributes and methods\nof the File class.
Be aware that files created in this way are not automatically closed.\nThe following approach may be used to close files automatically:
\n>>> from django.core.files import File\n\n# Create a Python file object using open() and the with statement\n>>> with open("/path/to/hello.world", "w") as f:\n... myfile = File(f)\n... myfile.write("Hello World")\n...\n>>> myfile.closed\nTrue\n>>> f.closed\nTrue\nClosing files is especially important when accessing file fields in a loop\nover a large number of objects. If files are not manually closed after\naccessing them, the risk of running out of file descriptors may arise. This\nmay lead to the following error:
\nOSError: [Errno 24] Too many open files\nBehind the scenes, Django delegates decisions about how and where to store files\nto a file storage system. This is the object that actually understands things\nlike file systems, opening and reading files, etc.
\nDjango’s default file storage is\n'django.core.files.storage.FileSystemStorage'. If you don’t\nexplicitly provide a storage system in the default key of the\nSTORAGES setting, this is the one that will be used.
See below for details of the built-in default file storage system, and see\nCome scrivere una storage class personalizzata for information on writing your own file\nstorage system.
\nThough most of the time you’ll want to use a File object (which delegates to\nthe proper storage for that file), you can use file storage systems directly.\nYou can create an instance of some custom file storage class, or – often more\nuseful – you can use the global default storage system:
>>> from django.core.files.base import ContentFile\n>>> from django.core.files.storage import default_storage\n\n>>> path = default_storage.save("path/to/file", ContentFile(b"new content"))\n>>> path\n'path/to/file'\n\n>>> default_storage.size(path)\n11\n>>> default_storage.open(path).read()\nb'new content'\n\n>>> default_storage.delete(path)\n>>> default_storage.exists(path)\nFalse\nSee File storage API for the file storage API.
\nDjango ships with a django.core.files.storage.FileSystemStorage class\nwhich implements basic local filesystem file storage.
For example, the following code will store uploaded files under\n/media/photos regardless of what your MEDIA_ROOT setting is:
from django.core.files.storage import FileSystemStorage\nfrom django.db import models\n\nfs = FileSystemStorage(location="/media/photos")\n\n\nclass Car(models.Model):\n ...\n photo = models.ImageField(storage=fs)\nCustom storage systems work the same way:\nyou can pass them in as the storage argument to a\nFileField.
You can use a callable as the storage\nparameter for FileField or\nImageField. This allows you to modify the used\nstorage at runtime, selecting different storages for different environments,\nfor example.
Your callable will be evaluated when your models classes are loaded, and must\nreturn an instance of Storage.
For example:
\nfrom django.conf import settings\nfrom django.db import models\nfrom .storages import MyLocalStorage, MyRemoteStorage\n\n\ndef select_storage():\n return MyLocalStorage() if settings.DEBUG else MyRemoteStorage()\n\n\nclass MyModel(models.Model):\n my_file = models.FileField(storage=select_storage)\nIn order to set a storage defined in the STORAGES setting you can\nuse storages:
from django.core.files.storage import storages\n\n\ndef select_storage():\n return storages["mystorage"]\n\n\nclass MyModel(models.Model):\n upload = models.FileField(storage=select_storage)\nBecause the callable is evaluated when your models classes are loaded, if you\nneed to override the STORAGES setting in tests, you should use a\nLazyObject subclass instead:
from django.core.files.storage import storages\nfrom django.utils.functional import LazyObject\n\n\nclass OtherStorage(LazyObject):\n def _setup(self):\n self._wrapped = storages["mystorage"]\n\n\nmy_storage = OtherStorage()\n\n\nclass MyModel(models.Model):\n upload = models.FileField(storage=my_storage)\nThe LazyObject delays the evaluation of the storage until it’s actually\nneeded, allowing override_settings() to take effect:
@override_settings(\n STORAGES={\n "mystorage": {\n "BACKEND": "django.core.files.storage.InMemoryStorage",\n }\n }\n)\ndef test_storage():\n model = MyModel()\n assert isinstance(model.upload.storage, InMemoryStorage)\n