sveltekit-medusa-client

A client library for communicating with a Medusa ecommerce backend in SvelteKit

Documentation

If you are not familiar with Medusa, you can learn more on the project web site.

Medusa is a set of commerce modules and tools that allow you to build rich, reliable, and performant commerce applications without reinventing core commerce logic. The modules can be customized and used to build advanced ecommerce stores, marketplaces, or any product that needs foundational commerce primitives. All modules are open-source and freely available on npm.

This client is designed to be used on the server. It cannot be exported to the browser. This means you must make your calls to your Medusa backend from your storefront server, not from the client browser. Calls to the library can be made from:

• A handler in hooks.server.js/ts
• A page load function in +page.server.js/ts
• A form action in +page.server.js/ts, or
• An API endpoint, aka +server.js/ts

One of the benefits of newer frameworks like SvelteKit is that they combine the fluid user experience of client-side reactivity with the ability to handle logic on the server when you choose to. Keeping your Medusa backend firewalled and accessible only to your storefront application server provides an additional layer of security versus having your backend directly exposed. This type of deployment also allows us to use tools like Turnstile or reCAPTCHA to provide some protection against bots and brute force attacks. Without firewalling your backend, it would not be of much use to implement turnstile protection on your frontend. It could easily be bypassed.

Example Project

You can view an example project using this client library here.

Installation

Create a new SvelteKit app if needed. Then, install this package.

yarn add sveltekit-medusa-client

You should set the location of your Medusa server as an environment variable. For example:

.env

MEDUSA_BACKEND_URL="http://localhost:9000"

Basic Usage

To create a new client, invoke the MedusaClient constructor, passsing the location of your Medusa server as an argument. For example:

+page.server.js

import { MedusaClient } from 'sveltekit-medusa-client'
import { MEDUSA_BACKEND_URL } from '$env/static/private'

export const load = async function () {
   const medusa = new MedusaClient(MEDUSA_BACKEND_URL)
   return {
      products: medusa.getProducts()
   }
}

Then, on the corresponding +page.svelte, you can use the products data you exported: (For more information on the data returned, refer to the Medusa API Documentation)

<script>
   export let data
   const products = data.products  
</script>

<ul>
{#each products as product}
   <li>
      Product id: {product.id}<br>
      Product handle: {product.handle}<br>
      {product.title}
   </li>
{:else}
   <p>No products returned</p>
{/each}
<ul>

Using the Client as a Singleton

One major drawback of the example above is that a new Medusa client is created for each page load.
You can prevent that by adding a small library in your project that creates a single shared client that can be imported where needed. For example:

lib/server/medusa.js

import { MedusaClient } from 'sveltekit-medusa-client'
import { MEDUSA_BACKEND_URL } from '$env/static/private'
export default new MedusaClient(MEDUSA_BACKEND_URL)

Now, on our +page.server.js load function, we can do this:

import medusa from '$lib/server/medusa'

export const load = async function () {
   return {
      products: medusa.getProducts()
   }
}

Client Options

A number of options give some flexibility to the client. The options object that can be injected in the client contructor takes this shape:

interface ClientOptions {
   timeout?: number
   retry?: number
   headers?: {}
   persistentCart?: boolean
   debug?: boolean
   logger?: Logger
   logFormat?: 'text' | 'json' | 'majel'
   excludedPaths?: string[]
   limitedPaths?: string[]
}

For example, you can create a new client instance like this:

import { MedusaClient } from 'sveltekit-medusa-client'
import { MEDUSA_BACKEND_URL, CLOUDFLARE_ACCESS_ID, CLOUDFLARE_ACCESS_SECRET } from '$env/static/private'
export default new MedusaClient(MEDUSA_BACKEND_URL, { 
   timeout: 3000,
   retry: 0,
   headers: {
      'CF-Access-Client-Id': CLOUDFLARE_ACCESS_ID,
      'CF-Access-Client-Secret': CLOUDFLARE_ACCESS_SECRET,
   },
   persistentCart: true,
   debug: true,
   logger: console,
   logFormat: 'json',
   excludedPaths: ['/store/cart','store/mycustomroute'],
   limitedPaths: ['/']
})

• timeout - The default is 8000, or 8 seconds. The length of time to wait for a response before aborting
• retry - The default is 3. The number of times to retry a timed out request
• headers - The default is undefined. An object of HTTP headers, as many as you want, which will be added to all requests sent to the backend. This can be useful in many situations. If you would like to access a server behind a proxy with bearer auth, you can pass the auth header in this property. You can also pass Cloudflare Access service auth credentials, as in the example above.
• persistentCart - The default is false. If true, the client will expect an endpoint at /store/customers/me/cart that will return the customer's cart. For now, this endpoint is not included in the Medusa core and must be added.
• debug - The default is false. If true, will log requests and responses to/from the Medusa backend for a better developer experience.
• logger - The default is console. You can inject your own logger instance if you already have one configured in the application. For example, a winston logger instance. Any logger that implements the info() and error() methods should work.
• logFormat - The default is json. You can change to 'text' if you need to for some reason.
• excludedPaths - The default is ['/store/auth']. An array of strings that should be checked to exclude paths from logging. The default can be added to, but not overridden. Requests to URIs on your medusa backend that contain one or more of these strings will not be logged.
• limitedPaths - The default is undefined. An array of strings that should be checked to reduce the level of detail when logging. Requests to URIs on your medusa backend that contain one or more of these strings will not log request or response content, only metadata. The url of the request will be logged, but not query params. To enable limited logging for all paths for more concise logging, use an array that contains the root path (['/']).

Authentication

Some methods in the library, like the getProducts method in the example above, need no authentication. Other methods need more context, such as whether the requester is a logged in user, or whether they have an existing shopping cart. The first argument passed to those methods is the special SvelteKit locals object. Locals on the server work much like a page or session store in the browser. They are a place to hold on to data related to this particular request that we may need somewhere else in the application before this request/response cycle is complete.

Use the middleware method handleRequest from this library to handle customer authentication on every request with very little effort. If the user is logged in, the user object will be available at locals.user. Middleware is added in SvelteKit via the hooks.server.js/ts file:

hooks.server.js

import medusa from '$lib/server/medusa'

export const handle = async ({ event, resolve }) => {
   event = await medusa.handleRequest(event)
   return await resolve(event)
}

Now, we can invoke methods that require information about the user and the cart.

+page.server.js

import medusa from '$lib/server/medusa'

export const load = async function ({ locals, cookies }) {
   return {
      cart: medusa.getCart(locals, cookies)
   }
}