144 lines
4.0 KiB
Python
144 lines
4.0 KiB
Python
"""
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42. Storing files according to a custom storage system
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``FileField`` and its variations can take a ``storage`` argument to specify how
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and where files should be stored.
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"""
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import shutil
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import tempfile
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from django.db import models
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from django.core.files.base import ContentFile
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from django.core.files.uploadedfile import SimpleUploadedFile
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from django.core.files.storage import FileSystemStorage
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from django.core.cache import cache
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temp_storage_location = tempfile.mkdtemp()
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temp_storage = FileSystemStorage(location=temp_storage_location)
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# Write out a file to be used as default content
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temp_storage.save('tests/default.txt', ContentFile('default content'))
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class Storage(models.Model):
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def custom_upload_to(self, filename):
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return 'foo'
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def random_upload_to(self, filename):
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# This returns a different result each time,
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# to make sure it only gets called once.
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import random
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return '%s/%s' % (random.randint(100, 999), filename)
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normal = models.FileField(storage=temp_storage, upload_to='tests')
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custom = models.FileField(storage=temp_storage, upload_to=custom_upload_to)
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random = models.FileField(storage=temp_storage, upload_to=random_upload_to)
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default = models.FileField(storage=temp_storage, upload_to='tests', default='tests/default.txt')
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__test__ = {'API_TESTS':"""
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# Attempting to access a FileField from the class raises a descriptive error
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>>> Storage.normal
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Traceback (most recent call last):
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...
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AttributeError: The 'normal' attribute can only be accessed from Storage instances.
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# An object without a file has limited functionality.
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>>> obj1 = Storage()
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>>> obj1.normal
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<FieldFile: None>
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>>> obj1.normal.size
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Traceback (most recent call last):
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...
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ValueError: The 'normal' attribute has no file associated with it.
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# Saving a file enables full functionality.
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>>> obj1.normal.save('django_test.txt', ContentFile('content'))
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>>> obj1.normal
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<FieldFile: tests/django_test.txt>
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>>> obj1.normal.size
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7
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>>> obj1.normal.read()
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'content'
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# File objects can be assigned to FileField attributes, but shouldn't get
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# committed until the model it's attached to is saved.
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>>> obj1.normal = SimpleUploadedFile('assignment.txt', 'content')
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>>> dirs, files = temp_storage.listdir('tests')
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>>> dirs
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[]
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>>> files.sort()
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>>> files
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['default.txt', 'django_test.txt']
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>>> obj1.save()
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>>> dirs, files = temp_storage.listdir('tests')
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>>> files.sort()
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>>> files
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['assignment.txt', 'default.txt', 'django_test.txt']
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# Files can be read in a little at a time, if necessary.
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>>> obj1.normal.open()
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>>> obj1.normal.read(3)
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'con'
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>>> obj1.normal.read()
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'tent'
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>>> '-'.join(obj1.normal.chunks(chunk_size=2))
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'co-nt-en-t'
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# Save another file with the same name.
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>>> obj2 = Storage()
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>>> obj2.normal.save('django_test.txt', ContentFile('more content'))
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>>> obj2.normal
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<FieldFile: tests/django_test_.txt>
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>>> obj2.normal.size
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12
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# Push the objects into the cache to make sure they pickle properly
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>>> cache.set('obj1', obj1)
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>>> cache.set('obj2', obj2)
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>>> cache.get('obj2').normal
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<FieldFile: tests/django_test_.txt>
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# Deleting an object deletes the file it uses, if there are no other objects
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# still using that file.
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>>> obj2.delete()
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>>> obj2.normal.save('django_test.txt', ContentFile('more content'))
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>>> obj2.normal
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<FieldFile: tests/django_test_.txt>
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# Default values allow an object to access a single file.
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>>> obj3 = Storage.objects.create()
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>>> obj3.default
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<FieldFile: tests/default.txt>
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>>> obj3.default.read()
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'default content'
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# But it shouldn't be deleted, even if there are no more objects using it.
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>>> obj3.delete()
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>>> obj3 = Storage()
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>>> obj3.default.read()
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'default content'
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# Verify the fix for #5655, making sure the directory is only determined once.
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>>> obj4 = Storage()
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>>> obj4.random.save('random_file', ContentFile('random content'))
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>>> obj4.random
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<FieldFile: .../random_file>
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# Clean up the temporary files and dir.
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>>> obj1.normal.delete()
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>>> obj2.normal.delete()
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>>> obj3.default.delete()
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>>> obj4.random.delete()
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>>> shutil.rmtree(temp_storage_location)
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"""}
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