django/tests/modeltests/files/models.py

"""
42. Storing files according to a custom storage system

``FileField`` and its variations can take a ``storage`` argument to specify how
and where files should be stored.
"""

import tempfile

from django.db import models
from django.core.files.base import ContentFile
from django.core.files.storage import FileSystemStorage
from django.core.cache import cache

temp_storage = FileSystemStorage(location=tempfile.gettempdir())

# Write out a file to be used as default content
temp_storage.save('tests/default.txt', ContentFile('default content'))

class Storage(models.Model):
    def custom_upload_to(self, filename):
        return 'foo'

    def random_upload_to(self, filename):
        # This returns a different result each time,
        # to make sure it only gets called once.
        import random
        return '%s/%s' % (random.randint(100, 999), filename)

    normal = models.FileField(storage=temp_storage, upload_to='tests')
    custom = models.FileField(storage=temp_storage, upload_to=custom_upload_to)
    random = models.FileField(storage=temp_storage, upload_to=random_upload_to)
    default = models.FileField(storage=temp_storage, upload_to='tests', default='tests/default.txt')

__test__ = {'API_TESTS':"""
# An object without a file has limited functionality.

>>> obj1 = Storage()
>>> obj1.normal
<FieldFile: None>
>>> obj1.normal.size
Traceback (most recent call last):
...
ValueError: The 'normal' attribute has no file associated with it.

# Saving a file enables full functionality.

>>> obj1.normal.save('django_test.txt', ContentFile('content'))
>>> obj1.normal
<FieldFile: tests/django_test.txt>
>>> obj1.normal.size
7
>>> obj1.normal.read()
'content'

# Files can be read in a little at a time, if necessary.

>>> obj1.normal.open()
>>> obj1.normal.read(3)
'con'
>>> obj1.normal.read()
'tent'
>>> '-'.join(obj1.normal.chunks(chunk_size=2))
'co-nt-en-t'

# Save another file with the same name.

>>> obj2 = Storage()
>>> obj2.normal.save('django_test.txt', ContentFile('more content'))
>>> obj2.normal
<FieldFile: tests/django_test_.txt>
>>> obj2.normal.size
12

# Push the objects into the cache to make sure they pickle properly

>>> cache.set('obj1', obj1)
>>> cache.set('obj2', obj2)
>>> cache.get('obj2').normal
<FieldFile: tests/django_test_.txt>

# Deleting an object deletes the file it uses, if there are no other objects
# still using that file.

>>> obj2.delete()
>>> obj2.normal.save('django_test.txt', ContentFile('more content'))
>>> obj2.normal
<FieldFile: tests/django_test_.txt>

# Default values allow an object to access a single file.

>>> obj3 = Storage.objects.create()
>>> obj3.default
<FieldFile: tests/default.txt>
>>> obj3.default.read()
'default content'

# But it shouldn't be deleted, even if there are no more objects using it.

>>> obj3.delete()
>>> obj3 = Storage()
>>> obj3.default.read()
'default content'

# Verify the fix for #5655, making sure the directory is only determined once.

>>> obj4 = Storage()
>>> obj4.random.save('random_file', ContentFile('random content'))
>>> obj4.random
<FieldFile: .../random_file>

# Clean up the temporary files.

>>> obj1.normal.delete()
>>> obj2.normal.delete()
>>> obj3.default.delete()
>>> obj4.random.delete()
"""}