🔒 DDB-Table

Strongly typed library for querying and modeling DynamoDB documents in TypeScript.

DDB-Table was built to provide strongly-typed data structures over DynamoDB tables. Using AWS
DocumentClient & TypeScript you can easily fetch and store any JSON document and validate it’s
structure statically. Query secondary indexes and run complicated update expressions without any
error on runtime.

await table
  .update('demo@example.com')
  .set('FullName', 'John Doe')
  // 🚨 TypeScript Error: 'fullName' is not assignable to 'Email' | 'FullName'
  .condition((cond) => cond.eq('fullName', 'Johnny Doe'))
  .exec();

Main Features

Strongly Typed - End-to-end TypeScript validation for your data.
Easy Query Expressions - Automatically escape name attributes and values.
Smart Projections - Make sure you only access the fields you project.
Query & Scan Indexes - Complete support for global or local indexes.
Pure JavaScript - Also works without TypeScript.

Install

npm i ddb-table

Usage

import Table from 'ddb-table';
import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocument } from '@aws-sdk/lib-dynamodb';
interface MessageSchema {
  threadId: string;
  timestamp: number;
  senderId: string;
  message: string;
  status: 'sent' | 'received';
  tags?: Set<string>;
  attachments: {
    name: string;
    URL: string;
  }[];
}
const client = new DynamoDBClient({
  // settings...
});
// create the basic table definition
const messages = new Table<MessageSchema, 'threadId', 'timestamp'>({
  tableName: 'Messages',
  primaryKey: 'threadId',
  sortKey: 'timestamp',
  documentClient: DynamoDBDocument.from(client);
});
const updateRes = await messages
  .update('john@gmail.com', 1588191225322)
  .set('message', 'Hello World!')
  .add('tags', new Set(['unread', 'important']))
  .set('attachments', (exp) =>
    exp.listAppend([{ name: 'Test', URL: 'demo.com' }]),
  )
  .return('ALL_NEW')
  .exec();
console.log(updateRes.Attributes);

Working with indexes as well:

// create a secondary index definition
type SenderTimestampIndex = Pick<
  MessageSchema,
  'threadId' | 'timestamp' | 'senderId'
>;
const outboxIndex = messages.index<
  SenderTimestampIndex,
  'senderId',
  'timestamp'
>('senderId-timestamp-index', 'senderId', 'timestamp');
const it = outboxIndex
  .query()
  .keyCondition((cond) => cond.eq('senderId', 'john@gmail.com'))
  .keyCondition((cond) =>
    cond.between('timestamp', Date.now() - 3600e3, Date.now()),
  )
  .project({ threadId: 1, message: 1 })
  .reverseIndex()
  .entries();
for await (const item of it) {
  console.log(item);
}

Error Handling

import { DynamoDBExceptionName } from 'ddb-table';
try {
  await table.put(...).exec();
} catch (err) {
  if ((err as DynamoDBServiceException)?.name === DynamoDBExceptionName.ConditionalCheckFailedException) {
    // handle exception
  }
}