从 aws lambda 事件检索存储桶名称时，我收到此错误。 ( “errorMessage”: “'Records'” “errorType”: “KeyError”)

Question

The command I'm trying to run is

def lambda_handler(event, context):
    print(event)
    
    #retrieve bucket name and file_key from the S3 event
    bucket_name = event['Records'][0]['s3']['bucket']['name']
    file_key = event['query']['Records'][0]['s3']['object']['key']

The result:

{'key1': 'value1', 'key2': 'value2', 'key3': 'value3'}

The error:

[ERROR] KeyError: 'Records'
Traceback (most recent call last):
  File "/var/task/lambda_function.py", line 12, in lambda_handler
    bucket_name = event['Records'][0]['s3']['bucket']['name']
END RequestId: 29150087-77bd-49db-a88b-61eb8a1645fd

Answer 1

Looking at the output of your print statement, it is clear that the event does not have a property called Records .

{
    'key1': 'value1', 
    'key2': 'value2', 
    'key3': 'value3'
}

So when you run event['Records'] it does not work. Because the JSON above does not have a property with name Records .

This would work if you have the following JSON:

{
    'Records': [],
    'key1': 'value1', 
    'key2': 'value2', 
    'key3': 'value3'
}

If that would be the JSON, then events['Records'] would return [] .

Based on the JSON of your event, I can tell that you are using the AWS Consoles "Test" features default event JSON.

You need to provide the proper JSON in the AWS console for AWS S3 Events.

It is documented here: Event message structure

The JSON should look like this:

{  
   "Records":[  
      {  
         "eventVersion":"2.2",
         "eventSource":"aws:s3",
         "awsRegion":"us-west-2",
         "eventTime":"The time, in ISO-8601 format, for example, 1970-01-01T00:00:00.000Z, when Amazon S3 finished processing the request",
         "eventName":"event-type",
         "userIdentity":{  
            "principalId":"Amazon-customer-ID-of-the-user-who-caused-the-event"
         },
         "requestParameters":{  
            "sourceIPAddress":"ip-address-where-request-came-from"
         },
         "responseElements":{  
            "x-amz-request-id":"Amazon S3 generated request ID",
            "x-amz-id-2":"Amazon S3 host that processed the request"
         },
         "s3":{  
            "s3SchemaVersion":"1.0",
            "configurationId":"ID found in the bucket notification configuration",
            "bucket":{  
               "name":"bucket-name",
               "ownerIdentity":{  
                  "principalId":"Amazon-customer-ID-of-the-bucket-owner"
               },
               "arn":"bucket-ARN"
            },
            "object":{  
               "key":"object-key",
               "size":"object-size",
               "eTag":"object eTag",
               "versionId":"object version if bucket is versioning-enabled, otherwise null",
               "sequencer": "a string representation of a hexadecimal value used to determine event sequence, only used with PUTs and DELETEs"
            }
         },
         "glacierEventData": {
            "restoreEventData": {
               "lifecycleRestorationExpiryTime": "The time, in ISO-8601 format, for example, 1970-01-01T00:00:00.000Z, of Restore Expiry",
               "lifecycleRestoreStorageClass": "Source storage class for restore"
            }
         }
      }
   ]
}