Lambda calling Lambda - how to access the payload in the second?

Question

I'm calling a Lambda from another Lambda asynchronously using:

payload = {"id":item['id']}
invoke_lambda = lambda_client.invoke(FunctionName="process",
                                     InvocationType="Event",
                                     Payload=json.dumps(payload)) # Use InvocationType="RequestResponse" for synchronous run

This is likely rather obvious, but I can't find the documentation for it - how do I access the payload in the second lambda defined as:

def process(event, context):
    (...)

bwest · Answer 1 · 2019-03-29T19:35:13.963

0

Your payload should be in the body of the event dict. Try json.loads(event['body']).get('id').

edited Mar 29 '19 at 19:35

answered Mar 29 '19 at 19:29

bwest

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score -1 · Answer 2 · answered Mar 29 '19 at 17:29

-1

Possible duplicate question -- Nodejs - Invoke an AWS.Lambda function from within another lambda function

Note, you may want to take a look at Step Functions to prevent Lambda A from incurring costs as it waits for Lambda B to complete.

answered Mar 29 '19 at 17:29

Nick Walsh

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Thanks for the suggestion, but I'm doing it in Python - not nodejs – Filipe Aleixo Mar 29 '19 at 17:35

score -1 · Accepted Answer · answered Mar 30 '19 at 23:35

-1

On the second lambda, you just need to do id = context['id']. When it's an asynchronous call, event doesn't come with the body key.

answered Mar 30 '19 at 23:35

Filipe Aleixo

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It would benefit any readers if you clarified the differences between reading from event and reading from context, and in what situations they should be accessed. – Chris Ivan Mar 15 '21 at 03:29
I got this error message `"errorMessage": "'LambdaContext' object is not subscriptable"` if I used context to retrieve payload. – James Huang Jan 31 '23 at 12:06

Lambda calling Lambda - how to access the payload in the second?

3 Answers3