Notice: Over the next few months, we're reorganizing the App Engine documentation site to make it easier to find content and better align with the rest of Google Cloud products. The same content will be available, but the navigation will now match the rest of the Cloud products.

Python 3.10 is now generally available.


Fetches data for a 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 that is entirely outside the boundaries of the blob will return an empty string. Attempting to fetch a negative index will raise an exception.

blob A BlobInfo, BlobKey, string, or Unicode representation of the BlobKey of the blob from which you want to fetch data.
start_index The start index of blob data to fetch. This value must not be negative.
end_index The end index (inclusive) of the blob data to fetch. This value must be greater than or equal to start_index.
rpc Optional UserRPC object.

A string that contains partial data of a blob. If the indexes are legal but outside of the boundaries of the blob, an empty string is returned.

TypeError If start_index or end_index are not indexes, or if blob is not a string, BlobKey or BlobInfo.
DataIndexOutOfRangeError If start_index is set to a value that is less than 0 or end_index is less than start_index.
BlobFetchSizeTooLargeError If the requested blob fragment is larger than MAX_BLOB_FETCH_SIZE.
BlobNotFoundError If the blob does not exist.