Added staging file previews support

3rd_party_apps/filetransfers/api.py

@@ -0,0 +1,43 @@
+from django.conf import settings
+from django.utils.importlib import import_module
+import mimetypes
+
+PREPARE_UPLOAD_BACKEND = getattr(settings,
+    'PREPARE_UPLOAD_BACKEND',
+    'filetransfers.backends.default.prepare_upload')
+SERVE_FILE_BACKEND = getattr(settings,
+    'SERVE_FILE_BACKEND',
+    'filetransfers.backends.default.serve_file')
+PUBLIC_DOWNLOAD_URL_BACKEND = getattr(settings,
+    'PUBLIC_DOWNLOAD_URL_BACKEND',
+    'filetransfers.backends.default.public_download_url')
+
+_backends_cache = {}
+
+# Public API
+def prepare_upload(request, url, private=False, backend=None):
+    handler = _load_backend(backend, PREPARE_UPLOAD_BACKEND)
+    return handler(request, url, private=private)
+
+def serve_file(request, file, backend=None, save_as=False, content_type=None):
+    # Backends are responsible for handling range requests.
+    handler = _load_backend(backend, SERVE_FILE_BACKEND)
+    filename = file.name.rsplit('/')[-1]
+    if save_as is True:
+        save_as = filename
+    if not content_type:
+        content_type = mimetypes.guess_type(filename)[0]
+    return handler(request, file, save_as=save_as, content_type=content_type)
+
+def public_download_url(file, backend=None):
+    handler = _load_backend(backend, PUBLIC_DOWNLOAD_URL_BACKEND)
+    return handler(file)
+
+# Internal utilities
+def _load_backend(backend, default_backend):
+    if backend is None:
+        backend = default_backend
+    if backend not in _backends_cache:
+        module_name, func_name = backend.rsplit('.', 1)
+        _backends_cache[backend] = getattr(import_module(module_name), func_name)
+    return _backends_cache[backend]