dynamodb-repository

DynamoDB repository for key-value indexed tables. Designed for Lambda use. Handles niceties like created and updated timestamps and default id creation.

Install

$ npm install @setho/dynamodb-repository --save

Usage

const { KeyValueRepository } = require('@setho/dynamodb-repository');

const myRepo = new KeyValueRepository({ 
  tableName: 'Items', // Required
  keyName: 'id',      // Required
  idOptions: {        // Optional
    prefix: 'ITEM#',   // Default is empty string
  },
  documentClient,     // Optional
});

Constructor

Use the optional idOptions constructor parameter to set an optional prefix to give your ids some human-readable context. The remainder of the key is a KSUID, which is both unique and lexicographically sortable. See segment.io's explanation of and motivation for KSUIDs here.

Additionally, you can inject your own DocumentClient if you are using a wrapped client (e.g., Dazn's powertools dynamodb client).

Environment Variables

This library takes advantage of AWS SDK connection reuse if you set environment variable AWS_NODEJS_CONNECTION_REUSE_ENABLED to 1. This was enabled by the AWS SDK in release 2.463.0. This can give a 3x speed improvement per call - I highly recommend setting this variable in your application.

Create

• Requires action dynamodb:PutItem
• Automatically adds a string key (this will overwrite any you may try to provide). Use constructor options to specify length and optional prefix.
• Automatically provides a createdAt and updatedAt timestamp in ISO-8601
• Returns what was saved; does not mutate the item passed in.

const mySavedItem = await myRepo.create(myItem);
mySavedItem.id  // itm_a4d02890b7174730b4bbbc
mySavedItem.createdAt  // 1979-11-04T09:00:00.000Z
mySavedItem.updatedAt  // 1979-11-04T09:00:00.000Z

Get by Key

• Requires action dynamodb:GetItem.
• Throws 404 if item not found using http-errors.

const myItem = await myRepo.get(id);

Get Many

• Requires action dynamodb:Scan
• Accepts optional parameter fields limit and cursor
  • limit defaults to 100
• Returns object with items (Array) and cursor (String)
  • items will always be an array; if nothing found, it will be empty
  • cursor will be present if there are more items to fetch, otherwise it will be undefined

// Example to pull 100 at time until you have all items
const allItems = [];
const getAllItems = async ({ limit, cursor = null }) => {
  const getResult = await myRepo.getMany({ limit, cursor });
  allItems.push(...getResult.items);
  if (getResult.cursor) {
    await getAllItems({ cursor: getResult.cursor });
  }
};
await getAllItems();
// The array allItems now has all your items. Go nuts.

Remove by Key

• Requires action dynamodb:DeleteItem

await myRepo.remove(id);

// More Coming Soon...