错误] TypeError: 'NoneType' object 不可下标

Question

So I was trying to make a serverless API using aws gateway , lambda and dyamodb for a movie database. The post part of the api seems to work fine it's the get part that is not working. I get the followinng error on postman while testing:

got this error on the postman with error code 502

{
    "message": "Internal server error"
}

My cloudwatch generated this error:

ERROR] TypeError: 'NoneType' object is not subscriptable
Traceback (most recent call last):
  File "/var/task/lambda_function.py", line 32, in lambda_handler
    response = getMovie(event['queryStringParameters']['movie_id'])

My code snippet:

def lambda_handler(event,context):
   logger.info(event)
   httpMethod=event['httpMethod']
   path=event['path']
if httpMethod==getMethod and path== healthPath:
    response=buildResponse(200)
elif httpMethod==getMethod and path == moviePath:
    response=getMovie(event['queryStringParameters']['movie_id'])
elif httpMethod==postMethod and path==moviePath:
    response=saveMovie(json.loads(event['body']))
elif httpMethod==patchMethod and path==moviePath:
    requestBody=json.loads(event['body'])
    response=modifyMovie(requestBody['movie_id'],requestBody['updateKey'],requestBody['updateValue'])
elif httpMethod==deleteMethod and path==moviePath:
    requestBody=json.loads(event['body'])
    response=deleteMovie(requestBody['movie_id'])
else:
    
    response=buildResponse(404,"Error Generated")
return response

Logger info says this: logger.info(event) Does anyone has a clue how to navigate out of this? Thank you!

Answer 1

You should probably rewrite your code to use event.get('...') . This will probably not correct your problem but it will make it easier to figure out what is wrong.

def lambda_handler(event,context):
   logger.info(event)
   httpMethod = event.get('httpMethod')
   path = event.get('path')
   if httpMethod == getMethod and path == healthPath:
     response = buildResponse(200)
   elif httpMethod == getMethod and path == moviePath:
     params = event.get('queryStringParameters')
     if params is None:
         return buildResponse(400, "queryStringParameter is None!")
      
     movie_id = params.get('movie_id')
     if movie_id is None:
         return buildResponse(400, "movie_id is None!")


     ...