def test_object_exists(blobstore: BlobStore,
bucket: str,
match: str,
test_type: ObjectTest = ObjectTest.EXACT) -> bool:
"""
Test if an object exists in the BlobStore
:param blobstore: the blobstore to check
:param bucket: the bucket to check in the blobstore
:param match: the string to match against; this is _not_ a regex pattern, strings must match exactly
:param test_type: the type of test to conduct, prefix matches test if the object name starts with the match string,
exact matches must match the full string
:return: test bool
"""
if test_type == ObjectTest.PREFIX:
try:
blobstore.list(bucket, prefix=match).__iter__().__next__()
except StopIteration:
return False
else:
return True
elif test_type == ObjectTest.EXACT:
try:
blobstore.get_user_metadata(bucket, match)
return True
except BlobNotFoundError:
return False
else:
raise ValueError(f"Not a valid storage object test type: " +
test_type.name)
def write_file_metadata(handle: BlobStore, dst_bucket: str, file_uuid: str,
file_version: str, document: str):
# what's the target object name for the file metadata?
metadata_key = f"files/{file_uuid}.{file_version}"
# if it already exists, then it's a failure.
try:
handle.get_user_metadata(dst_bucket, metadata_key)
except BlobNotFoundError:
pass
else:
raise BlobAlreadyExistsError()
handle.upload_file_handle(dst_bucket, metadata_key,
io.BytesIO(document.encode("utf-8")))