processing pdf documents using bedrock runtime

I am trying to use AWS Bedrock Runtime for document understanding:

(model:amazon.nova-premier-v1:0)

Here is my current code:

def process():
    with open("file.pdf", "rb") as f:
        document_bytes = f.read()
    bedrock_client = boto3.client("bedrock-runtime", "us-east-1")
    response = bedrock_client.converse(
        modelId=MODEL_ID,
        messages=[
            {
                "role": "user",
                "content": [
                    {
                        "text": "explain this document",
                        "document": {
                            "format": "pdf",
                            "name": "file",
                            "source": {
                                "bytes": document_bytes,
                            },
                        },
                    },
                ],
            },
        ],
    )

    print(response)

    return response

Here is the error I am encountering:

botocore.exceptions.ParamValidationError: Parameter validation failed:
Invalid number of parameters set for tagged union structure messages[0].content[0]. Can only set one of the following keys: text, image, document, video, toolUse, toolResult, guardContent, cachePoint, reasoningContent.

The code works fine if I remove the messages[0].content[0].document

but according to the error message 'document' is part of the tagged union.

I looked at the Docs, the example shows that 'document' can be used this way.

The example on the docs is similar to what I wrote. Can someone explain why is it still throwing this error.

The content parameter is an array. You have to pass the document as one element of the array, and the text as another element, something like this:

messages=[
            {
                "role": "user",
                "content": [
                    {
                        "document": {
                            "format": "pdf",
                            "name": "file",
                            "source": {
                                "bytes": document_bytes,
                            },
                        },
                    },
                    {
                        "text": "explain this document",
                    },
                ],
            },
        ],