DocumentClient incorrectly marshalls binary data types when using convertClassInstanceToMap: true

[dabrowne]

Checkboxes for prior research

• I've gone through Developer Guide and API reference
• I've checked AWS Forums and StackOverflow.
• I've searched for previous similar issues and didn't find any solution.

Describe the bug

When writing data using DynamoDBDocumentClient with marshallOptions.convertClassInstanceToMap = true, binary data values are incorrectly written to Dynamo as the "M" (map) data type rather than the "B" (binary) data type.

SDK version number

@aws-sdk/lib-dynamodb@3.504.0

Which JavaScript Runtime is this issue in?

All

Details of the browser/Node.js/ReactNative version

All

Reproduction Steps

const client = DynamoDBDocumentClient.from(new DynamoDBClient(), {
  marshallOptions: {
    convertClassInstanceToMap: true,
  },
});

client.send(new PutCommand({
  TableName: "my-table",
  Item: {
    key: "my-key",
    data: Buffer.from("enchilada"),
  },
}));

Observed Behavior

The marshalled DynamoDB JSON that is written to the database for the data attribute contains a Map whose value is equivalent to the result of converting the Buffer to a plain object by iterating over its keys using Object.entries:

"data": {
  "M": {
   "0": {
    "N": "101"
   },
   "1": {
    "N": "110"
   },
   "2": {
    "N": "99"
   },
   "3": {
    "N": "104"
   },
   "4": {
    "N": "105"
   },
   "5": {
    "N": "108"
   },
   "6": {
    "N": "97"
   },
   "7": {
    "N": "100"
   },
   "8": {
    "N": "97"
   }
  }
}

Expected Behavior

The marshalled DynamoDB JSON that is written to the database should contain the data attribute as a binary value:

"data": {
  "B": "ZW5jaGlsYWRh"
}

Possible Solution

This bug was introduced with #5697 which blindly converts anything that has typeof of object into a plain JS object.

This fails to account for the fact that there are a large number of types that fit this signature but should be left intact, as is accounted for here and here.

I'd imagine this change has also broken marshalling for other data type such as Set.

Additional Information/Context

No response

[kuhe]

Thanks for reporting this. A fix was released in https://github.com/aws/aws-sdk-js-v3/releases/tag/v3.523.0.

https://www.npmjs.com/package/@aws-sdk/lib-dynamodb/v/3.523.0

[dabrowne]

Great turnaround. Thanks @kuhe!

[kuhe]

Related report of the issue affecting AWS Lambda provided SDKs: #5868

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