Unable to append data into Azure storage using Python

Question

I am using the below code to append data to Azure blob using python.

from azure.storage.blob import AppendBlobService
append_blob_service = AppendBlobService(account_name='myaccount', account_key='mykey')

# The same containers can hold all types of blobs
append_blob_service.create_container('mycontainer')

# Append blobs must be created before they are appended to
append_blob_service.create_blob('mycontainer', 'myappendblob')
append_blob_service.append_blob_from_text('mycontainer', 'myappendblob', u'Hello, world!')

append_blob = append_blob_service.get_blob_to_text('mycontainer', 'myappendblob')

The above code works fine, but when I tried to insert new data, the old data gets overwritten. Is there any way I can append data to 'myappendblob'

Are you calling the same code every time you try to append contents to the blob? — Gaurav Mantri
– Gaurav Mantri, Commented Jun 29, 2022 at 16:18

Gaurav Mantri · Accepted Answer · 2022-06-29 17:08:59Z

1

Considering you are calling the same code to append the data, the issue is with the following line of code:

append_blob_service.create_blob('mycontainer', 'myappendblob')

If you read the documentation for create_blob method, you will notice the following:

Creates a blob or overrides an existing blob. Use if_none_match=* to prevent overriding an existing blob.

So essentially you are overriding the blob every time you call your code.

You should call this method with if_none_match="*" as the documentation suggests. If the blob exists, your code will throw an exception which you will need to handle.

edited Jun 29, 2022 at 17:08

answered Jun 29, 2022 at 16:46

Gaurav Mantri

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4 Comments

SanjanaSanju Over a year ago

append_blob_service.create_blob('raw', 'appendblob2',if_none_match=*) it give me invalid syntax. Kindly let me know what im missing here. Thank you

Gaurav Mantri Over a year ago

Try append_blob_service.create_blob('raw', 'appendblob2',if_none_match="*") (essentially put * in double quotes).

SanjanaSanju Over a year ago

Thank you it worked. Is there any way we can load the data to a table from Python.

Gaurav Mantri Over a year ago

Is there any way we can load the data to a table from Python - Please ask a separate question for this and provide all the details there.

RithwikBojja · Accepted Answer · 2022-06-30 11:05:26Z

Try this code which is taken from the Document and it is given by @Harsh Jain ,

from azure.storage.blob import AppendBlobService
   def append_data_to_blob(data):
     service = AppendBlobService(account_name="<Storage acc name>",

       account_key="<Storage acc key>")

     try:

       service.append_blob_from_text(container_name="<name of Conatiner >", blob_name="<The name of file>", text = data)

     except:

       service.create_blob(container_name="<name of Conatiner >", blob_name="<the name of file>")

       service.append_blob_from_text(container_name="<name of Conatiner>", blob_name="<the name of file>", text = data)

     print('Data got Appended ')

 append_data_to_blob('Hi blob')

Taken References from:

https://www.educative.io/answers/how-to-append-data-in-blob-storage-in-azure-using-python

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