faunadb-store.js

/**
 * CustomSessionStorage implementation with FaunaDb for your Node API Shopify app.
 *
 * On Fauna Dashboard, in my database, I created a Collection "Sessions" (with a TTL of 2 days, but configure it as you wish).
 * I also added an Index "session_by_id" with Terms set as  "data.id" and Serialized.
 *
 * In the constructor, replace my settings with yours to make the connection.
 * If you have a different Collection and/or Index, then also update each method to use the correct configuration.
 * 
 * @author Alexandre DEBUSSCHÈRE <alexandre@kosmonaft.dev>
 * @see https://github.com/Shopify/shopify-node-api/blob/main/docs/usage/customsessions.md
 * @see https://fauna.com/
 */

import faunadb from "faunadb";
import "dotenv/config";
import { Session } from "@shopify/shopify-api/dist/auth/session/index.js";

const q = faunadb.query;

class FaunaDbStore {
  constructor() {
    this.client = new faunadb.Client({
      secret: process.env.FAUNADB_SECRET,
      domain: "db.eu.fauna.com",
      port: 443,
      scheme: "https",
    });
  }

  /**
   * @param session
   * @returns {Promise<boolean>}
   */
  async storeCallback(session) {
    try {
      await this.client.query(
        // Upsert
        q.Let(
          {
            match: q.Match(q.Index("session_by_id"), session.id),
            data: { data: session },
          },
          q.If(
            q.Exists(q.Var("match")),
            q.Update(q.Select("ref", q.Get(q.Var("match"))), q.Var("data")),
            q.Create(q.Collection("Sessions"), q.Var("data"))
          )
        )
      );

      return true;
    } catch (err) {
      throw new Error(err);
    }
  }

  /**
   * @param id
   * @returns {Promise<undefined|*>}
   */
  async loadCallback(id) {
    let reply = undefined;

    try {
      await this.client
        .query(q.Get(q.Match(q.Index("session_by_id"), id)))
        .then((response) => (reply = response.data));

      if (!reply) {
        return undefined;
      }

      return Session.cloneSession(reply, reply.id);
    } catch (err) {
      throw new Error(err);
    }
  }

  /**
   * @param id
   * @returns {Promise<boolean>}
   */
  async deleteCallback(id) {
    try {
      await this.client.query(
        q.Delete(q.Select("ref", q.Get(q.Match(q.Index("session_by_id"), id))))
      );

      return true;
    } catch (err) {
      throw new Error(err);
    }
  }
}

export default FaunaDbStore;

index.js

// server/index.js
// ...
import faunadb from "faunadb";
import FaunaDbStore from "./storage/faunadb-store.js";

const sessionStorage = new FaunaDbStore();

Shopify.Context.initialize({
  API_KEY: process.env.SHOPIFY_API_KEY,
  API_SECRET_KEY: process.env.SHOPIFY_API_SECRET,
  SCOPES: process.env.SCOPES.split(","),
  HOST_NAME: process.env.HOST.replace(/https:\/\//, ""),
  API_VERSION: ApiVersion.April22,
  IS_EMBEDDED_APP: true,
  // This should be replaced with your preferred storage strategy
  SESSION_STORAGE:
    process.env.NODE_ENV === "production"
      ? new Shopify.Session.CustomSessionStorage(
          sessionStorage.storeCallback.bind(sessionStorage),
          sessionStorage.loadCallback.bind(sessionStorage),
          sessionStorage.deleteCallback.bind(sessionStorage)
        )
      : new Shopify.Session.MemorySessionStorage(),
});