def fetch_data(blob, start_index, end_index):
"""Fetch data for blob.
Fetches a fragment of a blob up to MAX_BLOB_FETCH_SIZE in length. Attempting
to fetch a fragment that extends beyond the boundaries of the blob will return
the amount of data from start_index until the end of the blob, which will be
a smaller size than requested. Requesting a fragment which is entirely
outside the boundaries of the blob will return empty string. Attempting
to fetch a negative index will raise an exception.
Args:
blob: BlobInfo, BlobKey, str or unicode representation of BlobKey of
blob to fetch data from.
start_index: Start index of blob data to fetch. May not be negative.
end_index: End index (inclusive) of blob data to fetch. Must be
>= start_index.
Returns:
str containing partial data of blob. If the indexes are legal but outside
the boundaries of the blob, will return empty string.
Raises:
TypeError if start_index or end_index are not indexes. Also when blob
is not a string, BlobKey or BlobInfo.
DataIndexOutOfRangeError when start_index < 0 or end_index < start_index.
BlobFetchSizeTooLargeError when request blob fragment is larger than
MAX_BLOB_FETCH_SIZE.
BlobNotFoundError when blob does not exist.
"""
if isinstance(blob, BlobInfo):
blob = blob.key()
return blobstore.fetch_data(blob, start_index, end_index)
def fetch_data(blob, start_index, end_index):
"""Fetch data for blob.
Fetches a fragment of a blob up to MAX_BLOB_FETCH_SIZE in length. Attempting
to fetch a fragment that extends beyond the boundaries of the blob will return
the amount of data from start_index until the end of the blob, which will be
a smaller size than requested. Requesting a fragment which is entirely
outside the boundaries of the blob will return empty string. Attempting
to fetch a negative index will raise an exception.
Args:
blob: BlobInfo, BlobKey, str or unicode representation of BlobKey of
blob to fetch data from.
start_index: Start index of blob data to fetch. May not be negative.
end_index: End index (inclusive) of blob data to fetch. Must be
>= start_index.
Returns:
str containing partial data of blob. If the indexes are legal but outside
the boundaries of the blob, will return empty string.
Raises:
TypeError if start_index or end_index are not indexes. Also when blob
is not a string, BlobKey or BlobInfo.
DataIndexOutOfRangeError when start_index < 0 or end_index < start_index.
BlobFetchSizeTooLargeError when request blob fragment is larger than
MAX_BLOB_FETCH_SIZE.
BlobNotFoundError when blob does not exist.
"""
if isinstance(blob, BlobInfo):
blob = blob.key()
return blobstore.fetch_data(blob, start_index, end_index)