Data

Core uses Amazon DynamoDB as its primary data store. This document covers how to work with DynamoDB in the context of the application.

DynamoDB Client

The system provides a configured DynamoDB client through the fastify instance passed to each plugin:

// The client is available in route handlers
const { dynamoClient } = fastify;

Key DynamoDB Tables

The system uses several DynamoDB tables:

• infra-core-api-events - Calendar events
• infra-core-api-iam-userroles - User role mappings
• infra-core-api-iam-grouproles - Group role mappings
• infra-core-api-membership-provisioning - Membership data
• infra-core-api-stripe-links - Stripe payment links
• infra-core-api-cache - Caching system
• infra-core-api-rate-limiter - Bucket-based rate limiting

Table names are defined in src/common/config.ts.

Basic DynamoDB Operations

The system uses the AWS SDK v3 for DynamoDB operations. Refer to the AWS SDK Documentation for details.

Using the Cache System

The system includes a DynamoDB-based caching system:

import { getItemFromCache, insertItemIntoCache } from "./functions/cache.js";

// Get cached item
const cachedData = await getItemFromCache(dynamoClient, "cache-key");
if (cachedData) {
  return cachedData;
}

// If not cached, get fresh data and cache it
const freshData = await getFreshData();
const expireAt = new Date();
expireAt.setTime(expireAt.getTime() + 3600000); // 1 hour
await insertItemIntoCache(dynamoClient, "cache-key", freshData, expireAt);

If the data can be cached locally per-lambda, you can also use the fastify.nodeCache object which implements the node-cache class.

Best Practices

1. Use marshall/unmarshall: Always use the marshall and unmarshall functions to convert between JavaScript objects and DynamoDB format.

2. Handle Edge Cases: Always check if items exist before using them.

3. Use Transactions: For operations that need atomicity, use DynamoDB Conditional Checks or Transactions. Remember that race conditions can easily crop up in a Lambda-based distributed system!

4. Error Handling: Use try/catch blocks and custom error types for database operations.