## Deprecation

:exclamation: **This project is deprecated**. This means Shopify will not be maintaining it going forward. If you are interested in building a Shopify app using first party tools then check out our other libraries:

* [@shopify/koa-shopify-auth](https://github.com/Shopify/quilt/tree/master/packages/koa-shopify-auth)
* [@shopify/koa-shopify-graphql-proxy](https://github.com/Shopify/quilt/blob/master/packages/koa-shopify-graphql-proxy/README.md)
* [shopify_app](https://github.com/Shopify/shopify_app)

These are all used internally and written against technologies we use for our own applications. Of course, if you wish to continue using Express, feel free to fork this codebase and continue it as you wish.

# shopify-express

A small set of abstractions that will help you quickly build an Express.js app that consumes the Shopify API.

## Example

```javascript
const express = require('express');
const shopifyExpress = require('@shopify/shopify-express');
const session = require('express-session');

const app = express();

const {
  SHOPIFY_APP_KEY,
  SHOPIFY_APP_HOST,
  SHOPIFY_APP_SECRET,
  NODE_ENV,
} = process.env;

// session is necessary for api proxy and auth verification
app.use(session({secret: SHOPIFY_APP_SECRET}));

const {routes, withShop} = shopifyExpress({
  host: SHOPIFY_APP_HOST,
  apiKey: SHOPIFY_APP_KEY,
  secret: SHOPIFY_APP_SECRET,
  scope: ['write_orders, write_products'],
  accessMode: 'offline',
  afterAuth(request, response) {
    const { session: { accessToken, shop } } = request;
    // install webhooks or hook into your own app here
    return response.redirect('/');
  },
});

// mounts '/auth' and '/api' off of '/shopify'
app.use('/shopify', routes);

// shields myAppMiddleware from being accessed without session
app.use('/myApp', withShop({authBaseUrl: '/shopify'}), myAppMiddleware)
```

## Shopify routes

```javascript
  const {routes} = shopifyExpress(config);
  app.use('/', routes);
```

Provides mountable routes for authentication and API proxying. The authentication endpoint also handles shop session storage using a configurable storage strategy (defaults to SQLite).

### `/auth/shopify`

Serves a login endpoint so merchants can access your app with a shop session.

### `/api`

Proxies requests to the api for the currently logged in shop. Useful to securely use api
endpoints from a client application without having to worry about CORS.

## shopStore

`shopifyExpress`'s config takes an optional `shopStore` key, You can use this to define a strategy for how the module will store your persistent data for user sessions.

### Strategies

By default the package comes with `MemoryStrategy`, `RedisStrategy`, and `SqliteStrategy`. If none are specified, the default is `MemoryStrategy`.

#### MemoryStrategy

Simple javascript object based memory store for development purposes. Do not use this in production!

```javascript
const shopifyExpress = require('@shopify/shopify-express');
const {MemoryStrategy} = require('@shopify/shopify-express/strategies');

const shopify = shopifyExpress({
  shopStore: new MemoryStrategy(redisConfig),
  ...restOfConfig,
});
```

#### RedisStrategy

Uses [redis](https://www.npmjs.com/package/redis) under the hood, so you can pass it any configuration that's valid for the library.

```javascript
const shopifyExpress = require('@shopify/shopify-express');
const {RedisStrategy} = require('@shopify/shopify-express/strategies');

const redisConfig = {
  // your config here
};

const shopify = shopifyExpress({
  shopStore: new RedisStrategy(redisConfig),
  ...restOfConfig,
});
```

#### SQLStrategy

Uses [knex](https://www.npmjs.com/package/knex) under the hood, so you can pass it any configuration that's valid for the library. By default it uses `sqlite3` so you'll need to run `yarn add sqlite3` to use it. Knex also supports `postgreSQL` and `mySQL`.

```javascript
const shopifyExpress = require('@shopify/shopify-express');
const {SQLStrategy} = require('@shopify/shopify-express/strategies');

// uses sqlite3 if no settings are specified
const knexConfig = {
  // your config here
};

const shopify = shopifyExpress({
  shopStore: new SQLStrategy(knexConfig),
  ...restOfConfig,
});
```

SQLStrategy expects a table named `shops` with a primary key `id`, and `string` fields for `shopify_domain` and `access_token`. It's recommended you index `shopify_domain` since it is used to look up tokens.

If you do not have a table already created for your store, you can generate one with `new SQLStrategy(myConfig).initialize()`. This returns a promise so you can finish setting up your app after it if you like, but we suggest you make a separate db initialization script, or keep track of your schema yourself.

#### Custom Strategy

`shopifyExpress` accepts any javascript class matching the following interface:

```javascript
  class Strategy {
    // shop refers to the shop's domain name
    getShop({ shop }): Promise<{accessToken: string}>
    // shop refers to the shop's domain name
    storeShop({ shop, accessToken }): Promise<{accessToken: string}>
  }
```

## Helper middleware

`const {middleware: {withShop, withWebhook}} = shopifyExpress(config);`

### `withShop`

`app.use('/someProtectedPath', withShop({authBaseUrl: '/shopify'}), someHandler);`

Express middleware that validates the presence of your shop session. The parameter you pass to it should match the base URL for where you've mounted the shopify routes.

### `withWebhook`

`app.use('/someProtectedPath', withWebhook, someHandler);`

Express middleware that validates the presence of a valid HMAC signature to allow webhook requests from shopify to your app.

## Example app

You can look at [shopify-node-app](https://github.com/shopify/shopify-node-app) for a complete working example.

## Gotchas

### Install route
For the moment the app expects you to mount your install route at `/install`. See [shopify-node-app](https://github.com/shopify/shopify-node-app) for details.

### Express Session
This library expects [express-session](https://www.npmjs.com/package/express-session) or a compatible library to be installed and set up for much of it's functionality. Api Proxy and auth verification functions won't work without something putting a `session` key on `request`.

It is possible to use auth without a session key on your request, but not recommended.

### Body Parser
This library handles body parsing on it's own for webhooks. If you're using webhooks you should make sure to follow express best-practices by only adding your body parsing middleware to specific routes that need it.

**Good**
```javascript
  app.use('/some-route', bodyParser.json(), myHandler);

  app.use('/webhook', withWebhook(myWebhookHandler));
  app.use('/', shopifyExpress.routes);
```

**Bad**
```javascript
  app.use(bodyParser.json());
  app.use('/some-route', myHandler);

  app.use('/webhook', withWebhook(myWebhookHandler));
  app.use('/', shopifyExpress.routes);
```


## Contributing

Contributions are welcome. Please refer to the [contributing guide](https://github.com/Shopify/shopify-express/blob/master/CONTRIBUTING.md) for more details.