The
BlobMigrationRecord
class stores the results of a blob
migration.
BlobMigrationRecord
is provided by the
google.appengine.ext.blobstore
module.
- Introduction
- Class methods:
- Instance properties:
Introduction
During the
migration of an application
from Master/Slave to HRD
in which blobs are copied from the Master/Slave app
to the new HRD app, new blob keys are assigned to the blobs copied to the new
app. The
BlobMigrationRecord
class stores the results of this
blob migration. In particular, for each blob, it contains the mapping of the old
blob key used in the original app and the new blob key for that blob in the new
app.
After the migration, you need to use this class if you have stored blob
keys inside serialized data within the Datastore. (Those serialized keys are
not updated automatically by the migration tool.) You need to replace the old
blob key for each blob with the corresponding new blob key using
BlobMigrationRecord.get_new_blob_key()
, which returns the new blob
key corresponding to the old one supplied to the method
Class Methods
The
BlobMigrationRecord
class has the following class methods:
- BlobMigrationRecord.get_by_blob_key ( old_blob_key )
-
Returns a
BlobMigrationRecord
object that represents the blob migration data for the given old blob key. The use of this method is optional. You don't need to use this method to get new blob keys that map to the old blob keys&emdash;you can use BlobMigrationRecord.get_new_blob_key() directly.Arguments
- old_blob_key
-
A
BlobKey
value.
- BlobMigrationRecord.get_new_blob_key ( old_blob_key )
-
Returns the new blob key that maps to the supplied old blob key.
Arguments
- old_blob_key
-
The
BlobKey
for a blob prior to a blob migration.
- BlobMigrationRecord.kind ()
-
Returns the kind (
blobstore.BLOB_MIGRATION_KIND
).
Instance Properties
A
BlobMigrationRecord
instance has one instance property,
new_blob_ref
which is a
blob
reference
containing the new blob key.
- new_blob_ref
-
Blob reference containing the new blob key value corresponding to the
BlobMigrationRecord
instance's old blob key value.