파일 관리하기¶

모델에서 파일 다루기¶

FileField 또는 :class:`~django.db.models.ImageField`를 사용하는 경우, Django는 해당 파일을 다룰 때 사용할 수 있는 API를 제공합니다.

아래, 이미지를 저장하기 위해 :class:`~django.db.models.ImageField`를 사용하는 모델을 예로 들어봅시다:

from django.db import models

class Car(models.Model):
    name = models.CharField(max_length=255)
    price = models.DecimalField(max_digits=5, decimal_places=2)
    photo = models.ImageField(upload_to='cars')
    specs = models.FileField(upload_to='specs')

모든 Car 인스턴스는 첨부된 사진에 대한 정보를 가져올 수 있는 photo 속성을 가지고 있을 것입니다:

>>> car = Car.objects.get(name="57 Chevy")
>>> car.photo
<ImageFieldFile: cars/chevy.jpg>
>>> car.photo.name
'cars/chevy.jpg'
>>> car.photo.path
'/media/cars/chevy.jpg'
>>> car.photo.url
'http://media.example.com/cars/chevy.jpg'

이 객체 –예시에서 car.photo–는 File 객체로서, 아래 나열된 메소드와 속성을 모두 가지고 있습니다.

예를 들어, name 속성을 바꿔 파일의 이름을 파일 저장소의 상대경로(만약 기본값으로 지정된 :class:`~django.core.files.storage.FileSystemStorage`를 사용하고 있다면, :setting:`MEDIA_ROOT`가 된다.)로 지정할 수 있다:

>>> import os
>>> from django.conf import settings
>>> initial_path = car.photo.path
>>> car.photo.name = 'cars/chevy_ii.jpg'
>>> new_path = settings.MEDIA_ROOT + car.photo.name
>>> # Move the file on the filesystem
>>> os.rename(initial_path, new_path)
>>> car.save()
>>> car.photo.path
'/media/cars/chevy_ii.jpg'
>>> car.photo.path == new_path
True

To save an existing file on disk to a FileField:

>>> from pathlib import Path
>>> from django.core.files import File
>>> path = Path('/some/external/specs.pdf')
>>> car = Car.objects.get(name='57 Chevy')
>>> with path.open(mode='rb') as f:
...     car.specs = File(f, name=path.name)
...     car.save()

>>> from PIL import Image
>>> car = Car.objects.get(name='57 Chevy')
>>> car.photo.width
191
>>> car.photo.height
287
>>> image = Image.open(car.photo)
# Raises ValueError: seek of closed file.
>>> car.photo.open()
<ImageFieldFile: cars/chevy.jpg>
>>> image = Image.open(car.photo)
>>> image
<PIL.JpegImagePlugin.JpegImageFile image mode=RGB size=191x287 at 0x7F99A94E9048>

파일 객체¶

Internally, Django uses a django.core.files.File instance any time it needs to represent a file.

Most of the time you’ll use a File that Django’s given you (i.e. a file attached to a model as above, or perhaps an uploaded file).

만약 File``을 직접 만들어야 한다면, 가장 쉬운 방법은 파이썬의 빌트인 ``file 객체를 활용하여 만드는 것입니다:

>>> from django.core.files import File

# Create a Python file object using open()
>>> f = open('/path/to/hello.world', 'w')
>>> myfile = File(f)

Now you can use any of the documented attributes and methods of the File class.

Be aware that files created in this way are not automatically closed. The following approach may be used to close files automatically:

>>> from django.core.files import File

# Create a Python file object using open() and the with statement
>>> with open('/path/to/hello.world', 'w') as f:
...     myfile = File(f)
...     myfile.write('Hello World')
...
>>> myfile.closed
True
>>> f.closed
True

Closing files is especially important when accessing file fields in a loop over a large number of objects. If files are not manually closed after accessing them, the risk of running out of file descriptors may arise. This may lead to the following error:

OSError: [Errno 24] Too many open files

File storage¶

Behind the scenes, Django delegates decisions about how and where to store files to a file storage system. This is the object that actually understands things like file systems, opening and reading files, etc.

Django’s default file storage is given by the DEFAULT_FILE_STORAGE setting; if you don’t explicitly provide a storage system, this is the one that will be used.

See below for details of the built-in default file storage system, and see How to write a custom storage class for information on writing your own file storage system.

>>> from django.core.files.base import ContentFile
>>> from django.core.files.storage import default_storage

>>> path = default_storage.save('path/to/file', ContentFile(b'new content'))
>>> path
'path/to/file'

>>> default_storage.size(path)
11
>>> default_storage.open(path).read()
b'new content'

>>> default_storage.delete(path)
>>> default_storage.exists(path)
False

from django.core.files.storage import FileSystemStorage
from django.db import models

fs = FileSystemStorage(location='/media/photos')

class Car(models.Model):
    ...
    photo = models.ImageField(storage=fs)

from django.conf import settings
from django.db import models
from .storages import MyLocalStorage, MyRemoteStorage


def select_storage():
    return MyLocalStorage() if settings.DEBUG else MyRemoteStorage()


class MyModel(models.Model):
    my_file = models.FileField(storage=select_storage)