Category: Express

I’ve always wanted to build an API, but was scared away by just how complicated things looked. I’d read a lot of tutorials that start with “first, install this library and this library and this library” without explaining why that was important. I’m kind of a Luddite when it comes to these things.

Well, I recently rolled up my sleeves and got my hands dirty. I wanted to build and deploy a simple read-only API, and goshdarnit, I wasn’t going to let some scary dependency lists and fancy cutting-edge services stop me¹.

What I discovered is that underneath many of the tutorials and projects out there is a small, easy-to-understand set of tools and techniques. In less than an hour and with only 30 lines of code, I believe anyone can write and deploy their very own read-only API. You don’t have to be a senior full-stack engineer — a basic grasp of JavaScript and some experience with npm is all you need.

At the end of this article you’ll be able to deploy your very own API without the headache of managing a server. I’ll list out each dependency and explain why we’re incorporating it. I’ll also give you an intro to some of the newer concepts involved, and provide links to resources to go deeper.

Let’s get started!

A rundown of the API concepts

There are a couple of common ways to work with APIs. But let’s begin by (super briefly) explaining what an API is all about: reading and updating data.

Over the past 20 years, some standard ways to build APIs have emerged. REST (short for REpresentational State Transfer) is one of the most common. To use a REST API, you make a call to a server through a URL — say api.example.com/rest/books — and expect to get a list of books back in a format like JSON or XML. To get a single book, we’d go back to the server at a URL — like api.example.com/rest/books/123 — and expect the data for book #123. Adding a new book or updating a specific book’s data means more trips to the server at similar, purpose-defined URLs.

That’s the basic idea of two concepts we’ll be looking at here: GraphQL and Serverless.

GraphQL

Applications that do a lot of getting and updating of data make a lot of API calls. Complicated software, like Twitter, might make hundreds of calls to get the data for a single page. Collecting the right data from a handful of URLs and formatting it can be a real headache. In 2012, Facebook developers starting looking for new ways to get and update data more efficiently.

Their key insight was that for the most part, data in complicated applications has relationships to other data. A user has followers, who are each users themselves, who each have their own followers, and those followers have tweets, which have replies from other users. Drawing the relationships between data results in a graph and that graph can help a server do a lot of clever work formatting and sending (or updating) data, and saving front-end developers time and frustration. Graph Query Language, aka GraphQL, was born.

GraphQL is different from the REST API approach in its use of URLs and queries. To get a list of books from our API using GraphQL, we don’t need to go to a specific URL (like our api.example.com/graphql/books example). Instead, we call up the API at the top level — which would be api.example.com/graphql in our example — and tell it what kind of information we want back with a JSON object:

{
  books {
    id
    title
    author
  }
}

The server sees that request, formats our data, and sends it back in another JSON object:

{
  "books" : [
    {
      "id" : 123
      "title" : "The Greatest CSS Tricks Vol. I"
      "author" : "Chris Coyier"
    }, {
      // ...
    }
  ]
}

Sebastian Scholl compares GraphQL to REST using a fictional cocktail party that makes the distinction super clear. The bottom line: GraphQL allows us to request the exact data we want while REST gives us a dump of everything at the URL.

Concept 2: Serverless

Whenever I see the word “serverless,” I think of Chris Watterston’s famous sticker.

Similarly, there is no such thing as a truly “serverless” application. Chris Coyier nice sums it up his “Serverless” post:

What serverless is trying to mean, it seems to me, is a new way to manage and pay for servers. You don’t buy individual servers. You don’t manage them. You don’t scale them. You don’t balance them. You aren’t really responsible for them. You just pay for what you use.

The serverless approach makes it easier to build and deploy back-end applications. It’s especially easy for folks like me who don’t have a background in back-end development. Rather than spend my time learning how to provision and maintain a server, I often hand the hard work off to someone (or even perhaps something) else.

It’s worth checking out the CSS-Tricks guide to all things serverless. On the Ideas page, there’s even a link to a tutorial on building a serverless API!

Picking our tools

If you browse through that serverless guide you’ll see there’s no shortage of tools and resources to help us on our way to building an API. But exactly which ones we use requires some initial thought and planning. I’m going to cover two specific tools that we’ll use for our read-only API.

Tool 1: NodeJS and Express

Again, I don’t have much experience with back-end web development. But one of the few things I have encountered is Node.js. Many of you are probably aware of it and what it does, but it’s essentially JavaScript that runs on a server instead of a web browser. Node.js is perfect for someone coming from the front-end development side of things because we can work directly in JavaScript — warts and all — without having to reach for some back-end language.

Express is one of the most popular frameworks for Node.js. Back before React was king (How Do You Do, Fellow Kids?), Express was the go-to for building web applications. It does all sorts of handy thing like routing, templating, and error handling.

I’ll be honest: frameworks like Express intimidate me. But for a simple API, Express is extremely easy to use and understand. There’s an official GraphQL helper for Express, and a plug-and-play library for making a serverless application called serverless-http. Neat, right?!

Tool 2: Netlify functions

The idea of running an application without maintaining a server sounds too good to be true. But check this out: not only can you accomplish this feat of modern sorcery, you can do it for free. Mind blowing.

Netlify offers a free plan with serverless functions that will give you up to 125,000 API calls in a month. Amazon offers a similar service called Lambda. We’ll stick with Netlify for this tutorial.

Netlify includes Netlify Dev which is a CLI for Netlify’s platform. Essentially, it lets us run a simulation of our in a fully-featured production environment, all within the safety of our local machine. We can use it to build and test our serverless functions without needing to deploy them.

At this point, I think it’s worth noting that not everyone agrees that running Express in a serverless function is a good idea. As Paul Johnston explains, if you’re building your functions for scale, it’s best to break each piece of functionality out into its own single-purpose function. Using Express the way I have means that every time a request goes to the API, the whole Express server has to be booted up from scratch — not very efficient. Deploy to production at your own risk.

Let’s get building!

Now that we have out tools in place, we can kick off the project. Let’s start by creating a new folder, navigating to fit in terminal, then running npm init  on it. Once npm creates a package.json file, we can install the dependencies we need. Those dependencies are:

1. Express
2. GraphQL and express-graphql. These allow us to receive and respond to GraphQL requests.
3. Bodyparser. This is a small layer that translates the requests we get to and from JSON, which is what GraphQL expects.
4. Serverless-http. This serves as a wrapper for Express that makes sure our application can be used on a serverless platform, like Netlify.

That’s it! We can install them all in a single command:

npm i express express-graphql graphql body-parser serverless-http

We also need to install Netlify Dev as a global dependency so we can use it as a CLI:

npm i -g netlify-dev

File structure

There’s a few files that are required for our API to work correctly. The first is netlify.toml which should be created at the project’s root directory. This is a configuration file to tell Netlify how to handle our project. Here’s what we need in the file to define our startup command, our build command and where our serverless functions are located:

[build]


  # This command builds the site
  command = "npm run build"


  # This is the directory that will be deployed
  publish = "build"


  # This is where our functions are located
  functions = "functions"

That functions line is super important; it tells Netlify where we’ll be putting our API code.

Next, let’s create that /functions folder at the project’s root, and create a new file inside it called api.js.  Open it up and add the following lines to the top so our dependencies are available to use and are included in the build:

const express = require("express");
const bodyParser = require("body-parser");
const expressGraphQL = require("express-graphql");
const serverless = require("serverless-http");

Setting up Express only takes a few lines of code. First, we’ll initial Express and wrap it in the serverless-http serverless function:

const app = express();
module.exports.handler = serverless(app);

These lines initialize Express, and wrap it in the serverless-http function. module.exports.handler lets Netlify know that our serverless function is the Express function.

Now let’s configure Express itself:

app.use(bodyParser.json());
app.use(
  "/",
  expressGraphQL({
    graphiql: true
  })
);

These two declarations tell Express what middleware we’re running. Middleware is what we want to happen between the request and response. In our case, we want to parse JSON using bodyparser, and handle it with express-graphql. The graphiql:true configuration for express-graphql will give us a nice user interface and playground for testing.

Defining the GraphQL schema

In order to understand requests and format responses, GraphQL needs to know what our data looks like. If you’ve worked with databases then you know that this kind of data blueprint is called a schema. GraphQL combines this well-defined schema with types — that is, definitions of different kinds of data — to work its magic.

The very first thing our schema needs is called a root query. This will handle any data requests coming in to our API. It’s called a “root” query because it’s accessed at the root of our API— say, api.example.com/graphql.

For this demonstration, we’ll build a hello world example; the root query should result in a response of “Hello world.”

So, our GraphQL API will need a schema (composed of types) for the root query. GraphQL provides some ready-built types, including a schema, a generic object², and a string.

Let’s get those by adding this below the imports:

const {
  GraphQLSchema,
  GraphQLObjectType,
  GraphQLString
} = require("graphql");

Then we’ll define our schema like this:

const schema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'HelloWorld',
    fields: () => ({ /* we'll put our response here */ })
  })
})

The first element in the object, with the key query, tells GraphQL how to handle a root query. Its value is a GraphQL object with the following configuration:

• name – A reference used for documentation purposes
• fields – Defines the data that our server will respond with. It might seem strange to have a function that just returns an object here, but this allows us to use variables and functions defined elsewhere in our file without needing to define them first³.

const schema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: "HelloWorld",
    fields: () => ({
      message: {
        type: GraphQLString,
        resolve: () => "Hello World",
      },
    }),
  }),
});

The fields function returns an object and our schema only has a single message field so far. The message we want to respond with is a string, so we specify its type as a GraphQLString. The resolve function is run by our server to generate the response we want. In this case, we’re only  returning “Hello World” but in a more complicated application, we’d probably use this function to go to our database and retrieve some data.

That’s our schema! We need to tell our Express server about it, so let’s open up api.js and make sure the Express configuration is updated to this:

app.use(
  "/",
  expressGraphQL({
    schema: schema,
    graphiql: true
  })
);

Running the server locally

Believe it or not, we’re ready to start the server! Run netlify dev in Terminal from the project’s root folder. Netlify Dev will read the netlify.toml configuration, bundle up your api.js function, and make it available locally from there. If everything goes according to plan, you’ll see a message like “Server now ready on http://localhost:8888.” 

If you go to localhost:8888 like I did the first time, you might be a little disappointed to get a 404 error.

But fear not! Netlify is running the function, only in a different directory than you might expect, which is /.netlify/functions. So, if you go to localhost:8888/.netlify/functions/api, you should see the GraphiQL interface as expected. Success!

The screen we get is the GraphiQL playground and we can use it to test out the API. First, clear out the comments in the left pane and replace them with the following:

{
  message
}

This might seem a little… naked… but you just wrote a GraphQL query! What we’re saying is that we’d like to see the message field we defined in api.js. Click the “Run” button, and on the righth, you’ll see the following:

{
  "data": {
    "message": "Hello World"
  }
}

I don’t know about you, but I did a little fist pump when I did this the first time. We built an API!

Bonus: Redirecting requests

One of my hang-ups while learning about Netlify’s serverless functions is that they run on the /.netlify/functions path. It wasn’t ideal to type or remember it and I nearly bailed for another solution. But it turns out you can easily redirect requests when running and deploying on Netlfiy. All it takes is creating a file in the project’s root directory called _redirects (no extension necessary) with the following line in it:

/api /.netlify/functions/api 200!

This tells Netlify that any traffic that goes to yoursite.com/api should be sent to /.netlify/functions/api. The 200! bit instructs the server to send back a status code of 200 (meaning everything’s OK).

Deploying the API

To deploy the project, we need to connect the source code to Netlfiy. I host mine in a GitHub repo, which allows for continuous deployment.

After connecting the repository to Netlfiy, the rest is automatic: the code is processed and deployed as a serverless function! You can log into the Netlify dashboard to see the logs from any function.

Conclusion

Just like that, we are able to create a serverless API using GraphQL with a few lines of JavaScript and some light configuration. And hey, we can even deploy — for free. 

The possibilities are endless. Maybe you want to create your own personal knowledge base, or a tool to serve up design tokens. Maybe you want to try your hand at making your own PokéAPI. Or, maybe you’re interesting in working with GraphQL.

Regardless of what you make, it’s these sorts of technologies that are getting more and more accessible every day. It’s exciting to be able to work with some of the most modern tools and techniques without needing a deep technical back-end knowledge.

If you’d like to see at the complete source code for this project, it’s available on GitHub.

Some of the code in this tutorial was adapted from Web Dev Simplified’s “Learn GraphQL in 40 minutes” article. It’s a great resource to go one step deeper into GraphQL. However, it’s also focused on a more traditional server-full Express.

The post Building Serverless GraphQL API in Node with Express and Netlify appeared first on CSS-Tricks.