Python Azure SDK how to get a previous version of a blob

Question

I am currently using python v3.8.8 with version 12.9.0 of azure.storage.blob and 1.14.0 of azure.core.

I want to use the python SDK in azure to control blob versioning. Ideally I would like the following 2 functions for a given BlobClient.

• Get a version of the blob by the specified versionId.
• Set a version of this blob to be the 'current version' of the blob.

Within my azure account I have activated versioning. This is my set up so far.

from azure.storage.blob import ContainerClient

container_client = ContainerClient(
  my_account_name, 
  my_container_name, 
  credential = my_credentials
)

container_client.upload_blob(my_blob_name, dummy_data)

blob_client = container_client.get_blob_client(my_blob_name)

blob_properties = blob_client.get_blob_properties()

for key, value in blob_properties.__dict__.items():
  print(f'{key}: {value}')

When looking through the blob properties I can see the version_id is this timestamp and is_current_version is True. I then used the follow to upload a new version.

blob_client.upload_blob(edited_dummy_data, overwrite=True)

blob_properties = blob_client.get_blob_properties()

for key, value in blob_properties.__dict__.items():
  print(f'{key}: {value}')

Then the version ID has changed and is_current_version is still true. On azure portal I can see there is a previous version. I can list these version using the python SDK using the following code.

blob_list = container_client.list_blobs(name_starts_with = my_blob_name, include = ['versions'])

for blob_property in blob_list:
  print(blob_property.name, blob_property.version_id)

However when trying to get access to the different versions of the blobs using the following I only get returned the current version of the blob.

blob_list = container_client.list_blobs(name_starts_with = my_blob_name, include = ['versions'])

for blob_property in blob_list:

  blob_client = container_client.get_blob_client(blob_property)
  blob_properties = blob_client.get_blob_properties()

  for key, value in blob_properties.__dict__.items():
    print(f'{key}: {value}')

A similar question was posted about this here but not for python. Moreover I would like revert a blob to a previous id if required (I know this can be done in the azure portal using the guide here ).

I have tried using the parameter versionId in the name of the blob like below.

blob_client = container_client.get_blob_client(my_blob_name + '?versionId=' + old_version_id)

Looking at the documentation here there is no keyword for version id. Though I did try, to get an unsurprising error.

Any help would be greatly appreciated or simply knowing that this functionality is not available would also be useful.

Answer 1

get_blob_properties method accepts version_id parameter so what you would need to do is provide that when fetching the properties of a versioned blob.

Essentially you would need to change the following line of code:

blob_properties = blob_client.get_blob_properties()

to

blob_properties = blob_client.get_blob_properties(version_id='blob version id')