__enter__ error wheen trying to use boto3's transact_write_items

Question

I have the following code:

def create_report_and_update_user(db_client, report_info):
    # TODO:: This will correctly perform operations, but will return a __enter__ error. Figure out why...
    report_info = json.loads(json.dumps(report_info), parse_float=Decimal)
    user_email = report_info["email"]
    report_id = (
        "R-" + str(uuid.uuid4())
        if not report_info.get("report_id")
        else report_info.get("report_id")
    )

    report_data = {
        "report_id": report_id,
        "creation_date": str(datetime.now()),
        "email": user_email,
        "loan_details": report_info["loan_details"],
        "purchase_details": report_info["purchase_details"],
        "property_details": report_info["property_details"],
        "monthly_budget": report_info["monthly_budget"],
    }

    serializer = TypeSerializer()
    report_data = {
        key: serializer.serialize(value) for key, value in report_data.items()
    }
    try:
        print("open is assigned to %r" % open)
        with db_client.transact_write_items(
            TransactItems=[
                {
                    "Put": {
                        "TableName": REPORTS_TABLE_NAME,
                        "Item": report_data,
                        "ConditionExpression": "attribute_not_exists(report_id)",
                    }
                },
            ]
        ) as response:
            print("Inside transact_write_items")
            return response
    except Exception as e:
        print("HERE: ", e)

However, I'm getting "HERE: enter" printed out to console. What is strange is that my DynamoDB table does properly add a new entry.

I saw another stackoverflow post that advised typing print("open is assigned to %r" % open), but I get open is assigned to <built-in function open> as expected. I don't remember ever overwritting the open keyword...

Not sure if it will help, but I'm using Windows and testing via sam cli. To run the following code, I use : npx cdk ls; sam local invoke ReportManager-Lambda -t ./cdk.out/GlobalStack.template.json -e .\events\create_report.json

Answer 1

I'm going to take my comment above and turn it into an official answer. You are using with incorrectly. I get the exact behavior shown above when I write:

try:
    with [] as response:
        print('hello')
except Exception as e:
    print("here", e)

Your code above should just be:

    response = db_client.transact_write_items(....)

Because you wrote:

    with db_client.transact_write_items(.....) as response:

Python is evaluating the expression (which is succeeding, as you noted), and looking at the resulting value (result) and attempting to set response = result.__enter__(). The result of the transact_write_items() call has no __enter__ method, and you get the error seen.