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For django, this code snippet extends the FileField to allow for changing the backend storage at run time on a per file basis
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| """ | |
| Copyright (C) 2015 Fastboot Mobile, LLC. (http://fastbootmobile.com) | |
| Licensed under the Apache License, Version 2.0 (the "License"); | |
| you may not use this file except in compliance with the License. | |
| You may obtain a copy of the License at | |
| http://www.apache.org/licenses/LICENSE-2.0 | |
| Unless required by applicable law or agreed to in writing, software | |
| distributed under the License is distributed on an "AS IS" BASIS, | |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| See the License for the specific language governing permissions and | |
| limitations under the License. | |
| ============================================================================ | |
| DESCRIPTION: For django, this code snippet extends the FileField to allow for | |
| changing the backend storage at run time on a per file basis. | |
| Created for Fastboot Mobile by: Anthony King <anthonydking@gmail.com> | |
| """ | |
| import os | |
| from django.db.models.fields import files | |
| class _FieldFile(files.FieldFile): | |
| def __init__(self, instance, field, name): | |
| super(_FieldFile, self).__init__(instance, field, name) | |
| if callable(field.runtime_storage): | |
| self.storage = field.runtime_storage(self.instance) | |
| class _FileDescriptor(files.FileDescriptor): | |
| def __get__(self, instance=None, owner=None): | |
| f = super(_FileDescriptor, self).__get__(instance=instance, | |
| owner=owner) | |
| # We don't care about other type | |
| if not isinstance(f, _FieldFile): | |
| return f | |
| # This is unlikely to happen since the superclass function | |
| # does this already, and _FieldFile is an instance of file.FieldFile. | |
| if not hasattr(f, 'field'): | |
| f.instance = instance | |
| f.field = self.field | |
| f.storage = self.field.storage | |
| # Now we assign our runtime storage backend. if applicable | |
| if callable(self.field.runtime_storage): | |
| f.storage = self.field.runtime_storage(instance) | |
| return f | |
| class DynamicFileField(files.FileField): | |
| attr_class = _FieldFile | |
| descriptor_class = _FileDescriptor | |
| def __init__(self, verbose_name=None, name=None, upload_to='', | |
| storage=None, runtime_storage=None, **kwargs): | |
| self.runtime_storage = runtime_storage | |
| super(DynamicFileField, self).__init__(verbose_name, name, | |
| upload_to, storage, **kwargs) | |
| def get_filename(self, filename, instance=None): | |
| if callable(self.runtime_storage): | |
| if instance: | |
| storage = self.runtime_storage(instance) | |
| return os.path.normpath(storage.get_valid_name( | |
| os.path.basename(filename))) | |
| return os.path.normpath(self.storage.get_valid_name( | |
| os.path.basename(filename))) | |
| def generate_filename(self, instance, filename): | |
| return os.path.join(self.get_directory_name(), | |
| self.get_filename(filename, instance=instance)) |
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