poller.continuation_token() crashes if initial request use file stream as input

[anatolip]

• Package Name: azure-ai-documentintelligence
• Package Version: 1.0.0b4
• Operating System: Windows
• Python Version: 3.12.7

Describe the bug
poller.continuation_token() crashes if input file is passed as an octet-steam into initial begin_analyze_document call.

Exception is below:

Traceback (most recent call last):
  File "C:\temp\SDK_issue_report.py", line 25, in <module>
    poller_continuation_token = poller.continuation_token() # get continuation token FAILS
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\anatolip\AppData\Local\anaconda3\envs\py12\Lib\site-packages\azure\core\polling\_poller.py", line 224, in continuation_token
    return self._polling_method.get_continuation_token()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\anatolip\AppData\Local\anaconda3\envs\py12\Lib\site-packages\azure\core\polling\base_polling.py", line 651, in get_continuation_token
    return base64.b64encode(pickle.dumps(self._initial_response)).decode("ascii")
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: cannot pickle 'BufferedReader' instances

To Reproduce
Code below illustrates that continuation_token() works if file is passed to begin_analyze_document as base64 string, but if file is passed as a octet-stream, get continuation_token() fails.

from azure.core.credentials import AzureKeyCredential
from azure.ai.documentintelligence import DocumentIntelligenceClient
from azure.ai.documentintelligence.models import AnalyzeDocumentRequest
import base64, pickle, os

endpoint = os.environ["AZURE_DI_ENDPOINT"]
key = os.environ["AZURE_DI_KEY"]

path_to_sample_documents = r'c:\temp\SampleInvoice26andLineItems.pdf'

client = DocumentIntelligenceClient(endpoint=endpoint, credential=AzureKeyCredential(key))

with open(path_to_sample_documents, "rb") as f:
    poller = client.begin_analyze_document("prebuilt-layout", AnalyzeDocumentRequest(bytes_source=f.read()))
poller_continuation_token = poller.continuation_token() # get continuation token WORKS
decoded_token = pickle.loads(base64.b64decode(poller_continuation_token))
resultUrl = decoded_token.http_response.headers.get('Operation-Location')
print(f"Results URL from continuation_token: {resultUrl} \n")

with open(path_to_sample_documents, "rb") as f:
    poller = client.begin_analyze_document("prebuilt-layout", f, content_type="application/octet-stream")
print(f"ERROR during continuation_token!!!\n")
poller_continuation_token = poller.continuation_token() # get continuation token FAILS

[l0lawrence]

Hi @anatolip thanks for the feedback, we will get back to you asap.

[catalinaperalta]

Updating the labels on this issue since this needs to be addressed in azure.core. Relevant info about a solution:
"We need a __setstate__ in Response similar to what we did for PipelineContext here:

azure-sdk-for-python/sdk/core/azure-core/azure/core/pipeline/__init__.py

Line 90 in 6495ca4

def __setstate__(self, state: Dict[str, Any]) -> None:

" cc @lmazuel