AWS Lambda: key error when sending a POST message - amazon-web-services

Question

I have a very simple problem:
my lamda function works fine as long as i do not write something like "a = event["key"], but a = "test":
This is from Cloudwatch:
#message
[ERROR] KeyError: 'key1' Traceback (most recent call last):
#message
[ERROR] KeyError: 'key1' Traceback (most recent call last): File "/var/task/lambda_function.py", line 5, in lambda_handler a = event["key1]
This is what i have sent with postman (i even tried curl) in the body as raw data:
{
"key1": "value1",
"key2": "value2",
"key3": "value3"
}
My lamda function looks like this:
import json
def lambda_handler(event, context):
# TODO implement
a = event["key1"]
return {
'statusCode': 200,
'body': json.dumps(a)
}

Answer 1

REST Api LAMBDA will pass the request as is where as LAMBDA_PROXY will append additonal metadata on query parms, api keys, etc. so, the input request body is passed as json string as attribute body. json.loads(event['body']) will give us the actual request body.
More details on changing integration type is here
Below code can extract key1 from input json object for Lambda_Proxy.
import json
def lambda_handler(event, context):
print(event)
a = json.loads(event['body'])['key1']
return {
'statusCode': 200,
'body': json.dumps(a)
}

Answer 2

Fastest way for me was to use a HTTP API and use form-data with key1=test. Then i printed event["body"] and found out that my body was base64 encoded. I used the following code to make that visible:
import json
import base64
def lambda_handler(event, context):
# TODO implement
a = event["body"]
print(a)
message_bytes = base64.b64decode(a)
message = message_bytes.decode('ascii')
return {
'statusCode': 200,
'body': json.dumps(message)
}
The output was:
"----------------------------852732202793625384403314\r\nContent-Disposition: form-data; name=\"key1\"\r\n\r\ntest\r\n----------------------------852732202793625384403314--\r\n"