Accepting arguments

You can do lots with the hello world functions you built in the last exercise. Accepting arguments and data will let you do even more.

That's when cloud functions become as powerful as your other JavaScript.

We'll explore 3 ways to accept parameters:

1. As part of the URL path
2. As a query string
3. As a data payload

Vercel

Vercel's filename-based routing gives you the simplest approach to path params that I've ever seen 👉 name your file as /api/[param1]/[param2].js and anything in square brackets becomes a named value.

You get URL queries and data payloads in the req object.

Exercise

Create a new file in your hello world project, call it [name].js or [name].ts. Return a Hello <name> string.

Make your function return Hello <name>, beautiful day today <emoji> where the emoji comes from query or body params. Default to query, use body if emoji is undefined.

Use req.query for path and query params. Use req.body for body payload params.

Deploy with vercel, use default answers to prompts.

Solution

Netlify

Best I can tell, Netlify doesn't support path params. ☹️

Query and body params work though and they're all you need. The URLs aren't that pretty anyway.

Exercise

Add a happy-day.js file to your hello world project.

Make your function return Hello <name>, beautiful day today <emoji> where the emoji comes from query or body params. Default to query, use body if emoji is undefined.

Use event.queryStringParameters for query params and event.body for the body payload. You'll need to JSON.parse that one.

Deploy with netlify deploy, use defaults to answer any prompts.

Your function is live at <domain>/.netlify/functions/<filename>

Try your function with these terminal commands:

Solution

AWS Lambda

AWS Lambda lets you accept all 3 types of params.

Exercise

Move into exercise-2 from the serverless-workshop-exercises GitHub repository.

Create a src/happy-day.ts file. Use the same code as your Netlify solution from the previous exercise. Declare the event arg as APIGatewayEvent and change to a TypeScript export

exports.handler = async (event) => {
// becomes
export const handler = async (event: APIGatewayEvent) => {

TypeScript will force you to think about undefined params as well. We ignored that with Netlify.

Add your new method to serverless.yml and configure:

1. the handler path
2. a GET event
3. a POST event
4. a parametrized path with {name}

Try reading the name path param from event.pathParameters

Deploy with yarn deploy or npm run deploy

Solution

https://github.com/Swizec/serverless-workshop-exercises/tree/exercise-2-solution