如何淡化来自 dynamodb 流的 json答案

【问题标题】：How to desalinize json coming from dynamodb stream如何淡化来自 dynamodb 流的 json
【发布时间】：2020-07-28 13:21:06
【问题描述】：

event = event = {'Records': [{'eventID': '2339bc590c21035b84f8cc602b12c1d2', 'eventName': 'INSERT', 'eventVersion': '1.1', 'eventSource': 'aws:dynamodb', 'awsRegion': 'us-east-1', 'dynamodb': {'ApproximateCreationDateTime': 1595908037.0, 'Keys': {'id': {'S': '9'}}, 'NewImage': {'last_name': {'S': 'Hus'}, 'id': {'S': '9'}, 'age': {'S': '95'}}, 'SequenceNumber': '3100000000035684810908', 'SizeBytes': 23, 'StreamViewType': 'NEW_IMAGE'}, 'eventSourceARN': 'arn:aws:dynamodb:us-east-1:656441365658:table/glossary/stream/2020-07-28T00:26:55.462'}, {'eventID': 'bbd4073256ef3182b3c00f13ead09501', 'eventName': 'MODIFY', 'eventVersion': '1.1', 'eventSource': 'aws:dynamodb', 'awsRegion': 'us-east-1', 'dynamodb': {'ApproximateCreationDateTime': 1595908037.0, 'Keys': {'id': {'S': '2'}}, 'NewImage': {'last_name': {'S': 'JJ'}, 'id': {'S': '2'}, 'age': {'S': '5'}}, 'SequenceNumber': '3200000000035684810954', 'SizeBytes': 21, 'StreamViewType': 'NEW_IMAGE'}, 'eventSourceARN': 'arn:aws:dynamodb:us-east-1:656441365658:table/glossary/stream/2020-07-28T00:26:55.462'}, {'eventID': 'a9c90c0c4a5a4b64d0314c4557e94e28', 'eventName': 'INSERT', 'eventVersion': '1.1', 'eventSource': 'aws:dynamodb', 'awsRegion': 'us-east-1', 'dynamodb': {'ApproximateCreationDateTime': 1595908037.0, 'Keys': {'id': {'S': '10'}}, 'NewImage': {'last_name': {'S': 'Hus'}, 'id': {'S': '10'}, 'age': {'S': '95'}}, 'SequenceNumber': '3300000000035684810956', 'SizeBytes': 25, 'StreamViewType': 'NEW_IMAGE'}, 'eventSourceARN': 'arn:aws:dynamodb:us-east-1:656441365658:table/glossary/stream/2020-07-28T00:26:55.462'}, {'eventID': '288f4a424992e5917af0350b53f754dc', 'eventName': 'MODIFY', 'eventVersion': '1.1', 'eventSource': 'aws:dynamodb', 'awsRegion': 'us-east-1', 'dynamodb': {'ApproximateCreationDateTime': 1595908037.0, 'Keys': {'id': {'S': '1'}}, 'NewImage': {'last_name': {'S': 'V'}, 'id': {'S': '1'}, 'age': {'S': '2'}}, 'SequenceNumber': '3400000000035684810957', 'SizeBytes': 20, 'StreamViewType': 'NEW_IMAGE'}, 'eventSourceARN': 'arn:aws:dynamodb:us-east-1:656441365658:table/glossary/stream/2020-07-28T00:26:55.462'}]}

以上来自 dynamodb 流。我需要从上面提取一些值

代码低于没有返回

def deserialize(event):
    data = {}
    data["M"] = event
    return extract_some(data)
def extract_some(event):
    for key, value in list(event.items()):
        if (key == "NULL"):
            return None
        if (key == "S" or key == "BOOL"):
            return value

for record in event['Records']:
    doc =  deserialise(record['dynamodb']['NewImage'])
    print (doc)

预期结果

{'last_name': 'Hus', 'id': '9', 'age': '95'}
{'last_name': 'JJ', 'id': '2', 'age': '5'}
{'last_name': 'Hus', 'id': '10', 'age': '95'}
{'last_name': 'V', 'id': '1', 'age': '2'}

【问题讨论】：

在for 循环中，您拼错了deserialise，而node 是什么？你在哪里申报？或者它应该是什么？

标签： python json

【解决方案1】：

试试这个，

from pprint import pprint

result = []
for r in event['Records']:
    tmp = {}

    for k, v in r['dynamodb']['NewImage'].items():
        if "S" in v.keys() or "BOOL" in v.keys():
            tmp[k] = v.get('S', v.get('BOOL', False))
        elif 'NULL' in v:
            tmp[k] = None

    result.append(tmp)
    
pprint(result)

[{'age': '95', 'id': '9', 'last_name': 'Hus'},
 {'age': '5', 'id': '2', 'last_name': 'JJ'},
 {'age': '95', 'id': '10', 'last_name': 'Hus'},
 {'age': '2', 'id': '1', 'last_name': 'V'}]

【讨论】：

v.keys()中的“BOOL”是什么，v.get('BOOL', False)是什么
在第一种情况下检查给定键是否在 dict 中退出，在第二种情况下检查键是否存在，如果不返回该键的默认值。
你能查一下stackoverflow.com/questions/63618932/…