Map express to lambda

expressToLambda.js

export const mapFromLambda = (lambdaResponse, expressResponse) => {
  expressResponse.status(lambdaResponse.statusCode);
  if (lambdaResponse.headers) {
    Object.keys(lambdaResponse.headers).forEach((headerName) => {
      expressResponse.setHeader(headerName, lambdaResponse.headers[headerName]);
    });
  }
  expressResponse.send(lambdaResponse.body);
};

export const callHandler = (request, response, handler) => {
  const event = {
    httpMethod: request.method,
    body: request.body,
    pathParameters: request.params,
    queryStringParameters: request.query,
    headers: request.headers
  };

  const callback = (error, lambdaResponse) => {
    if (error === null) {
      mapFromLambda(lambdaResponse, response);
    } else {
      response.status(500);
      response.send(JSON.stringify({ message: error.message }));
    }
  };

  handler(event, {}, callback);
};

export default callHandler;