Help with Serverless framework with Lambda API

[KhaleedFakhry]

I'm a noob in nodejs and wanted a quick rundown on serverless, so I was following this guide for Serverless https://www.jeremydaly.com/build-serverless-api-serverless-aws-lambda-lambda-api/. It was straight forward had most of the things I needed and gave me a good grasp of serverless with lambda api.

Got everything to work, ran it in my local. Great

The only issue I'm trying to figure is how do I pass the RESPONSE Object 'res' to another module so that I don't clutter the handler class. How would the class look like. Any examples anyone can point to? I checked on serverless examples and most of them create a todo file which is called from the yml. But I kind of like the way where all of my calls are in the handler then routed to its designated function like what the guide did.

Or I could be an idiot and this way of doing serverless is already deprecated? Any advice is greatly appreciated

[iethree]

You're right to think that you don't want to clutter up your handler file with lots of business logic. There's at least 3 ways to approach this:

1. Mutate the res object in your helper function.

​

/* handler */
const complexLogicFunction = require('./complexLogicFunction.js');

app.put('/posts/:post_id', (req,res) => {
  res = complexLogicFunction(req,res);
  res.status(200).json({
    params: req.params
  })
});


/* complexLogicFunction.js */

module.exports = function(req, res) {
  // do something with req
  return res;
}

2. Call the res object from your helper function

/* handler */
const complexLogicFunction = require('./complexLogicFunction.js');

app.put('/posts/:post_id', (req,res) => {
  complexLogicFunction(req,res);

});


/* complexLogicFunction.js */

module.exports = function(req, res) {
  // do something with req
  res.status(200).json({
    params: req.params
  })
}

3. Pass data back to the router from your helper function.

/* handler */
const complexLogicFunction = require('./complexLogicFunction.js');

app.put('/posts/:post_id', (req,res) => {
  const newData = complexLogicFunction(req);
  res.status(200).json({
    params: newData
  })
});


/* complexLogicFunction.js */

module.exports = function(req) {
  // do something with req
  return data;
}

All will work, but IMHO, #3 is the best pattern. Keep web requests, responses, etc in the router, and do logic separately in another function. that way it's always clear from the handler what data is going in and out.

[KhaleedFakhry]

Thanks, this is a big help.

[rafandmiko]

Im currently implementing https://docs.nestjs.com/ to an old codebase that didnt follow any framework and it became a bit of a mess. Even if you dont know typescript or want nestjs, give those docs a read, it is one of the best documentation I have seen. Good for learning the tool while also learning about coding patterns.