Extensions Docs Server: Apps samples page

chrome/common/extensions/docs/server2/appengine_blobstore.py

+# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import blob_reference_store as datastore
+from blob_reference_store import BlobReferenceStore
+from appengine_wrappers import blobstore
+from appengine_wrappers import files
+
+BLOBSTORE_GITHUB = 'BlobstoreGithub'
+
+class AppEngineBlobstore(object):
+  """A wrapper around the blobstore API, which stores the blob keys in
+  datastore.
+  """
+  def __init__(self):
+    self._datastore = BlobReferenceStore('blobstore')
+
+  def Set(self, key, blob, namespace):
+    """Add a blob to the blobstore. |version| is used as part of the key so
+    multiple blobs with the same name can be differentiated.
+    """
+    key = namespace + '.' + key
+    filename = files.blobstore.create()
+    with files.open(filename, 'a') as f:
+      f.write(blob)
+    files.finalize(filename)
+    blob_key = files.blobstore.get_blob_key(filename)
+    self._datastore.Set(datastore.BLOB_REFERENCE_BLOBSTORE, key, blob_key)
+
+  def Get(self, key, namespace):
+    """Get a blob with version |version|.
+    """
+    key = namespace + '.' + key
+    blob_key = self._datastore.Get(datastore.BLOB_REFERENCE_BLOBSTORE, key)
+    if blob_key is None:
+      return None
+    blob_reader = blobstore.BlobReader(blob_key)
+    return blob_reader.read()
+
+  def Delete(self, key, namespace):
+    """Delete the blob with version |version| if it is found.
+    """
+    key = namespace + '.' + key
+    blob_key = self._datastore.Delete(datastore.BLOB_REFERENCE_BLOBSTORE, key)
+    if blob_key is None:
+      return
+    blob_key.delete()