How to stream data to azure block blob in python

Question

I want to stream data to azure block blob with python. The code below creates the blob but ends up with zero bytes. How can I make this work?

import io
import struct
from azure.storage.blob import BlockBlobService

storage = BlockBlobService('acct-xxx', 'key-xxx')
stream = io.BytesIO()
storage.create_blob_from_stream("mycontainer", "myblob", stream)
stream.write(struct.pack("d", 12.34))
stream.write(struct.pack("d", 56.78))
stream.close()

Answer 1

It seems that you've missed the key line of code：

stream.seek(0)

I set the stream's Position property to 0 then your code works.

import io
import struct
from azure.storage.blob import BlockBlobService

storage = BlockBlobService('acct-xxx', 'key-xxx')
stream = io.BytesIO()

stream.write(struct.pack("d", 12.34))
stream.write(struct.pack("d", 56.78))
stream.seek(0)
storage.create_blob_from_stream("mycontainer", "myblob", stream)
stream.close()

You could refer to this thread Azure storage: Uploaded files with size zero bytes.