Salesforce Function - Caching Example

index.js

export default async function (event, context, logger) {
  logger.info(`Invoking Datafunction with payload ${JSON.stringify(event.data || {})}`);

  const redis = await redisConnect();
  let cached = {};

  // Check Redis for cached entry first
  let big_biz_count = await redis.get(`big_biz`);

  if (big_biz_count) {
    // If cached entry found, return it and be done.
    logger.info(`Found cache entry = ${big_biz_count}`);
    cached = "true"
    redis.quit();

    return { big_biz_count, cached }
  }  else {
    // If cached entry not found, then:
    // 1. Run the Postgres query
    // 2. Store the result in Redis
    // 3. Return the result and be done

    logger.info(`did not find in cache, returned ${big_biz_count}`);
    cached = "false"

    const pg = await pgConnect();
    const { rows } = await pg.query('SELECT COUNT(*) FROM company WHERE employees>10000;');
    big_biz_count = rows[0].count.toString();

    redis.set(`big_biz`, big_biz_count, {
      EX: 30, // seconds to keep before expiring
      NX: true
    });

    // Close the connections   
    redis.quit();
    pg.end();

    // Return the value from Postgres, now stored in Redis
    return { big_biz_count, cached }
  }
}

/* Helper functions */

// Connect to PostgreSQL
async function pgConnect() {
  const DATABASE_URL = process.env.DATABASE_URL;
  if (!DATABASE_URL) {
    throw new Error("DATABASE_URL is not set");
  }
  const client = new Client({
    connectionString: DATABASE_URL,
    ssl: {
      rejectUnauthorized: false
    }
  });
  await client.connect();
  return client;
}

// Connect to Redis
async function redisConnect() {
  const REDIS_URL = process.env.REDIS_URL;
  if (!REDIS_URL) {
    throw new Error("REDIS_URL is not set");
  }
  const redis = createClient({
    url: process.env.REDIS_URL,
    socket: {
      tls: true,
      rejectUnauthorized: false
    }
  });
  await redis.connect();
  redis.on('error', err => {
    console.log('Error ' + err);
  });
  return redis;
}