python - AWS DynamoDB Stream python 转换原生格式

Question

我有一个由 DynamoDB 流触发的 Lambda 函数。我的问题是收到的事件的格式很奇怪(每个键/值都有类型)。

是否存在将整个文档转换为 native python 格式(无任何类型)的解决方法。我正在寻找一个动态解决方案，因为将来我想将此 lambda 与具有不同格式(多个字典/列表级别)的其他 DynamoDB 表流一​​起使用

示例:

{
  "Records": [
    {
      "eventID": "1",
      "eventVersion": "1.0",
      "dynamodb": {
        "Keys": {
          "Id": {
            "N": "101"
          }
        },
        "NewImage": {
          "Message": {
            "S": "New item!"
          },
          "Id": {
            "N": "101"
          }
        },
        "StreamViewType": "NEW_AND_OLD_IMAGES",
        "SequenceNumber": "111",
        "SizeBytes": 26
      },
      "awsRegion": "us-west-2",
      "eventName": "INSERT",
      "eventSourceARN": "arn:aws:dynamodb:us-west-2:account-id:table/ExampleTableWithStream/stream/2015-06-27T00:48:05.899",
      "eventSource": "aws:dynamodb"
    },
    {
      "eventID": "2",
      "eventVersion": "1.0",
      "dynamodb": {
        "OldImage": {
          "Message": {
            "S": "New item!"
          },
          "Id": {
            "N": "101"
          }
        },
        "SequenceNumber": "222",
        "Keys": {
          "Id": {
            "N": "101"
          }
        },
        "SizeBytes": 59,
        "NewImage": {
          "Message": {
            "S": "This item has changed"
          },
          "Id": {
            "N": "101"
          }
        },
        "StreamViewType": "NEW_AND_OLD_IMAGES"
      },
      "awsRegion": "us-west-2",
      "eventName": "MODIFY",
      "eventSourceARN": "arn:aws:dynamodb:us-west-2:account-id:table/ExampleTableWithStream/stream/2015-06-27T00:48:05.899",
      "eventSource": "aws:dynamodb"
    },
    {
      "eventID": "3",
      "eventVersion": "1.0",
      "dynamodb": {
        "Keys": {
          "Id": {
            "N": "101"
          }
        },
        "SizeBytes": 38,
        "SequenceNumber": "333",
        "OldImage": {
          "Message": {
            "S": "This item has changed"
          },
          "Id": {
            "N": "101"
          }
        },
        "StreamViewType": "NEW_AND_OLD_IMAGES"
      },
      "awsRegion": "us-west-2",
      "eventName": "REMOVE",
      "eventSourceARN": "arn:aws:dynamodb:us-west-2:account-id:table/ExampleTableWithStream/stream/2015-06-27T00:48:05.899",
      "eventSource": "aws:dynamodb"
    }
  ]
}

谢谢

Answer 1

我一直在使用它，直到现在它对我们很有用:

from boto3.dynamodb.types import TypeDeserializer

serializer = TypeDeserializer()

def deserialize(data):
    if isinstance(data, list):
        return [deserialize(v) for v in data]

    if isinstance(data, dict):
        try:
            return serializer.deserialize(data)
        except TypeError:
            return {k: deserialize(v) for k, v in data.items()}
    else:
        return data