Unable to infer a hanlder when using mangum

[94929]

Hi, I'm using mangum for serving lambda image and I get the following error:

{"errorMessage": "The adapter was unable to infer a handler to use for the event. This is likely related to how the Lambda function was invoked. (Are you testing locally? Make sure the request payload is valid for a supported handler.)", "errorType": "RuntimeError", "stackTrace": ["  File \"/var/lang/lib/python3.8/site-packages/mangum/adapter.py\", line 65, in __call__\n    handler = self.infer(event, context)\n", "  File \"/var/lang/lib/python3.8/site-packages/mangum/adapter.py\", line 55, in infer\n    raise RuntimeError(  # pragma: no cover\n"]}

Did anyone face the same issue? Any help would be appreciated.

[heisguyy]

I think the error should be with your request. What's your request like?

[heisguyy]

You have to mimick the structure of an event API gateway sends to a lambda proxy integration. You can see this structure in "Input format of a Lambda function for proxy integration" section of this article

[94929]

Thanks, I now have set my request as below:

curl -XPOST "http://localhost:3010/2015-03-31/functions/function/invocations" -d '{
        "resource": "/resources",
        "path": "/resources",
        "httpMethod": "POST",
        "headers": {"Content-Type": "application/json"}
        "requestContext": {},
        "body": {"count":1}
}'

And I get the following:

{"errorMessage": "'dict' object has no attribute 'encode'", "errorType": "AttributeError", "stackTrace": ["  File \"/var/lang/lib/python3.8/site-packages/mangum/adapter.py\", line 71, in __call__\n    http_cycle = HTTPCycle(handler.scope, handler.body)\n", "  File \"/var/lang/lib/python3.8/site-packages/mangum/handlers/api_gateway.py\", line 82, in body\n    return maybe_encode_body(\n", "  File \"/var/lang/lib/python3.8/site-packages/mangum/handlers/utils.py\", line 23, in maybe_encode_body\n    body = body.encode()\n"]}

Did you face the same issue when making a request?

[heisguyy]

The value of the body should be in quotes

"body": '{"count":1}' instead of "body":{"count":1}

[94929]

I did that in the first place, and got {"errorMessage": "Unable to unmarshal input: Expecting value: line 1 column 1 (char 0)", "errorType": "Runtime.UnmarshalError", "stackTrace": []} instead. So I thought the quotes for body is redundant as there already is quotes enclosing whole json on "-d".

[heisguyy]

Seems you are using a windows system. Check this