File storage refactoring, adding far more flexibility to Django's file handling. The new files.txt document has details of the new features.

This is a backwards-incompatible change; consult BackwardsIncompatibleChanges for details.

Fixes #3567, #3621, #4345, #5361, #5655, #7415.

Many thanks to Marty Alchin who did the vast majority of this work.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8244 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/files/models.py

@@ -0,0 +1,118 @@
+"""
+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()
+"""}