无法封送响应：JSONDecodeError

Question

我有一个AWS Stepfunction可以触发Lambda。不幸的是，我无法正确解码输入：

从AWS Stepfunction到Lambda的输入：

{
  "MessageNumber": 0,
  "message": {
    "MessageId": "ae5b5d59-6829-4a19-b508-2ba35614e2de",
    "ReceiptHandle": "AQEBJsP+Et+WcgstIR9kkA3sH4UDoxYYcoDT2YYa30K87Rx2wSEFaZNg3CNdsjE18LSDMNXWg7VoV/s/p0bSL0PaUxQ0FV34RAwavG0iGMi",
    "MD5OfBody": "a726ec7fdda41e454850580e1a2cf4b4",
    "Body": "{'stage': 'tst', 'directory': '\\\\\\\\mydomain\\\\data\\\\results', 'variableFilters': ['\\\\filters\\\\x1.txt', '\\\\filters\\\\a1.txt']}",
    "Attributes": {
      "SenderId": "xxx",
      "ApproximateFirstReceiveTimestamp": "xxx",
      "ApproximateReceiveCount": "2",
      "SentTimestamp": "xxx",
      "SequenceNumber": "xxx",
      "MessageDeduplicationId": "xxx",
      "MessageGroupId": "1"
    }
  }
}

Python代码如下所示：

def lambda_handler(event, context):
    print(f'Received Event: {event}')
    try:
        body = json.loads(event.get('message').get('Body'))
        stage = body["stage"]
        directory= body["directory"]
    except Exception as e:
        return (e)

我得到一个错误：

{
  "errorMessage": "Unable to marshal response: JSONDecodeError('Expecting property name enclosed in double quotes: line 1 column 2 (char 1)') is not JSON serializable",
  "errorType": "Runtime.MarshalError"
}

有人知道如何解决这个问题吗

提前谢谢

Answer 1

必须在body中用双引号替换简单引号。 因为在有效的JSON中，字符串以"开头和结尾

body = "{'stage': 'tst', 'directory': '\\\\\\\\mydomain\\\\data\\\\results', 'variableFilters': ['\\\\filters\\\\x1.txt', '\\\\filters\\\\a1.txt']}"
body = json.loads(body.replace('\'', '"'))