I'm running into a frequent
AttributeError: 'Document' object has no attribute '_key_name'
Error when I try to delete multiple documents from the datastore (same
entity group). This error only occurs when the delete request first
runs into a "Transaction collision". So for example I send these three
delete requests in quick succession:
DELETE /v1/documents/1-62?version=0
DELETE /v1/documents/1-1071?version=0
DELETE /v1/documents/1-64?version=0
The first two requests work fine. But in this case the third dumps a
Transaction collision and then a "no attribute '_key_name" stack trace
in the logs, and the delete fails to take place:
03-13 05:32AM 48.567 /v1/documents/1-1071?version=0 500 881ms 675ms-
cpu 1kb WriteRoom/1.3.1 CFNetwork/342.1 Darwin/9.4.1,gzip(gfe)
64.222.203.28 - jesse [13/Mar/2009:05:32:49 -0700] "DELETE /v1/
documents/1-1071?version=0 HTTP/1.1" 500 1406 - "WriteRoom/1.3.1
CFNetwork/342.1 Darwin/9.4.1,gzip(gfe)"
W 03-13 05:32AM 49.421
Transaction collision for entity group with key
datastore_types.Key.from_path('Account', 1L, _app=u'hogbaywriteroom').
Retrying...
E 03-13 05:32AM 49.422
'Document' object has no attribute '_key_name'
Traceback (most recent call last):
File "/base/python_lib/versions/1/google/appengine/ext/webapp/
__init__.py", line 511, in __call__
handler.delete(*groups)
File "/base/data/home/apps/hogbaywriteroom/1.332025726958922683/
documents.py", line 168, in g
return f(*new_args, **kw)
File "/base/data/home/apps/hogbaywriteroom/1.332025726958922683/
documents.py", line 198, in g
return f(*new_args, **kw)
File "/base/data/home/apps/hogbaywriteroom/1.332025726958922683/
documents.py", line 492, in delete
db.run_in_transaction(txn)
File "/base/python_lib/versions/1/google/appengine/api/
datastore.py", line 1654, in RunInTransaction
DEFAULT_TRANSACTION_RETRIES, function, *args, **kwargs)
File "/base/python_lib/versions/1/google/appengine/api/
datastore.py", line 1745, in RunInTransactionCustomRetries
result = function(*args, **kwargs)
File "/base/data/home/apps/hogbaywriteroom/1.332025726958922683/
documents.py", line 482, in txn
deleted = Deleted(parent=document.parent_key(), document_key=str
(document.key()))
File "/base/python_lib/versions/1/google/appengine/ext/db/
__init__.py", line 616, in key
elif self._key_name:
AttributeError: 'Document' object has no attribute '_key_name'
The problem doesn't seem related to the documents server state. Right
after that above failure I sent the same delete request again, and it
worked fine that time. So I'm 99 percent sure that the cause is the
transaction collision, but I'm not sure how to resolve it. Quite
possibly I'm doing something wrong in my code, here's when my delete
method looks like. If you need to see more code I'd be happy to
provide the @require_document code to. Just let me know.
@require_document
def delete(self, user_account, document_account, document):
version = self.request.get('version', None)
version = None if version == None else int(version)
if version == None:
self.error(400)
return
def txn():
if version != document.version:
raise ValueError, "Version does not match
document version"
deleted = Deleted(parent=document.parent_key(),
document_key=str
(document.key()))
document_account.documents_size -= document.edits_size
id_string = document.id_string()
account_emails = document.get_account_emails()
deleted.put()
document.delete()
document_account.put()
clear_memcache(id_string, account_emails)
try:
document_id = document.key().id()
db.run_in_transaction(txn)
for edit in Edit.gql("WHERE ANCESTOR IS :1",
db.Key.from_path
('Account', document_account.key().id(), 'Document', document_id)):
edit.delete()
if not api(self.request):
self.redirect('/documents', False)
except ValueError:
self.error(409)
except db.TransactionFailedError:
self.error(409)
Thanks for your help.
Jesse
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