How to return nothing in AWS API Gateway?

Question

Sorry for this dumb question, but I tried everything.

I have a AWS API Gateway from a Lambda function that I need to return only HTTP Code 200 with no body. If the lambda returns a empty string, the body shows "" (2 quotation marks). If the lambda returns null, the body shows the word null.

What is the catch? How to return a empty body?

For information, I am using a Slack dash command to call the API. So the call returns a HTTP 200 OK, and the result is sent by POST in a response url; so processing can be done after the HTTP result, in order to avoid timeout problems.

Answer 1

If you are using the "lambda proxy integration" in the "integration request" section (see attached screenshot), you can simply return an empty string through the following structure.

module.exports.hello = (event, context, callback) => {
  const response = {
    statusCode: 200,
    body: ''
  };
  callback(null, response);
};