AndrewIngram · June 18, 2013 09:22 · Jun 18, 2013 · Jun 18, 2013 · Jun 18, 2013 · Jun 18, 2013
diff --git a/storages → storages.py b/storages → storages.py
diff --git a/gistfile1.py → storages b/gistfile1.py → storages
diff --git a/gistfile1.txt → gistfile1.py b/gistfile1.txt → gistfile1.py
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,114 @@
+from django.conf import settings
+from django.core.files.storage import Storage
+from django.utils import importlib
+
+
+def load_class(class_string):
+    class_module, class_name = class_string.rsplit('.', 1)
+    class_module = importlib.import_module(class_module)
+    return getattr(class_module, class_name)
+
+
+class HybridStorage(Storage):
+    """
+    Allows you to declare a list of storage backends to use. For each operation,
+    each is accessed in sequence until one returns successfully.
+
+    The main use case is to allow us to develop with production imagery from S3,
+    but to transparently handle any file uploads with local file storage (so as
+    not to impact upon the production environment)
+    """
+
+    def __init__(self, backends=None):
+        if not backends:
+            backends = settings.HYBRID_STORAGE_BACKENDS
+        self.backends = []
+
+        for backend in backends:
+            if isinstance(backend, Storage):
+                self.backends.append(backend)
+            elif isinstance(backend, basestring):
+                self.backends.append(load_class(backend)())
+
+    def _open(self, name, mode='rb'):
+        for backend in self.backends:
+            try:
+                f = backend._open(name, mode=mode)
+                return f
+            except IOError:
+                continue
+        raise IOError('File does not exist: %s' % name)
+
+    def _save(self, name, content):
+        for backend in self.backends:
+            try:
+                result = backend._save(name, content)
+                return result
+            except IOError:
+                continue
+        raise IOError('Could not save file in any available backend')
+
+    def _backend_for_name(self, name):
+        for backend in self.backends:
+            if backend.exists(name):
+                return backend
+            continue
+        return None
+
+    def delete(self, name):
+        pass
+
+    def exists(self, name):
+        for backend in self.backends:
+            if backend.exists(name):
+                return True
+            continue
+        return False
+
+    def listdir(self, path):
+        """
+        Collect the results of `listdir` on all backends, and then deduplicate
+        """
+        collected_directories = []
+        collected_files = []
+        for backend in self.backends:
+            try:
+                directories, files = backend.listdir(path)
+                collected_directories.extend(directories)
+                collected_files.extend(files)
+            except:
+                pass
+        collected_directories = list(set(collected_directories))
+        collected_files = list(set(collected_files))
+
+        return collected_directories, collected_files
+
+    def size(self, name):
+        backend = self._backend_for_name(name)
+        if backend:
+            return backend.size(name)
+        return None
+
+    def url(self, name):
+        backend = self._backend_for_name(name)
+        if backend:
+            return backend.url(name)
+        return None
+
+    def accessed_time(self, name):
+        backend = self._backend_for_name(name)
+        if backend:
+            return backend.accessed_time(name)
+        return None
+
+    def created_time(self, name):
+        backend = self._backend_for_name(name)
+        if backend:
+            return backend.created_time(name)
+        return None
+
+    def modified_time(self, name):
+        backend = self._backend_for_name(name)
+        if backend:
+            return backend.modified_time(name)
+        return None
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