Parsing DdbJson from DynamoDB Streams events

When you use DynamoDB Streams and handle item changes with Lambda, the incoming events look like this:

{
    "Records": [
        {
            "eventID": "7de3041dd709b024af6f29e4fa13d34c",
            "eventName": "INSERT",
            "eventVersion": "1.1",
            "eventSource": "aws:dynamodb",
            "awsRegion": "region",
            "dynamodb": {
                "ApproximateCreationDateTime": 1479499740,
                "Keys": {
                    "Timestamp": {
                        "S": "2016-11-18:12:09:36"
                    },
                    "Username": {
                        "S": "John Doe"
                    }
                },
                "NewImage": {
                    "Timestamp": {
                        "S": "2016-11-18:12:09:36"
                    },
                    "Message": {
                        "S": "This is a bark from the Woofer social network"
                    },
                    "Username": {
                        "S": "John Doe"
                    }
                },
                "SequenceNumber": "13021600000000001596893679",
                "SizeBytes": 112,
                "StreamViewType": "NEW_IMAGE"
            },
            "eventSourceARN": "arn:aws:dynamodb:region:123456789012:table/BarkTable/stream/2016-11-16T20:42:48.104"
        }
    ]
}

Is there any way to parse the NewImage into the dotnet model?

DdbJsonReader is marked as internal and DynamoDbLowLevelContext does not expose such functionality.

[lezzi]

Hey @wjax, sorry for the late reply. A long time ago I was experimenting with lambda and here is the example that parses a lambda stream into the request object.

It is also a good example of how to deserialize and map a DynamoDb JSON into a class. It is possible but requires applying attributes in certain cases (one of the reasons it is internal).

If you are up for testing the LambdaSerializer class from that branch, we should be able to polish it and add it to the library 🤔 .

[wjax]

Hey @wjax, sorry for the late reply. A long time ago I was experimenting with lambda and here is the example that parses a lambda stream into the request object.

It is also a good example of how to deserialize and map a DynamoDb JSON into a class. It is possible but requires applying attributes in certain cases (one of the reasons it is internal).

If you are up for testing the LambdaSerializer class from that branch, we should be able to polish it and add it to the library 🤔 .

Many many thanks! I will come back after having tested it!