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

TypeScript/ES6

import { KeyValueRepository } from '@setho/dynamodb-repository';

const myRepo = new KeyValueRepository({
  tableName: 'Items', // Required
  keyName: 'id', // Required
  idOptions: {
    // Optional
    prefix: 'ITEM_', // Default is empty string
  },
  documentClient, // Required - V3 DynamoDBDocumentClient from @aws-sdk/lib-dynamodb
});

JavaScript

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, // Required - V3 DynamoDBDocumentClient from @aws-sdk/lib-dynamodb
});

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 ULID, which is both unique and lexicographically sortable. See an explanation of and motivation for ULIDs here.

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);

Update

• Requires dynamodb:UpdateItem
• Honors revision check; it will only update if the revision on disk is the one you are updating. Will return a 409 if the revision has changed underneath you.
• Will perform a partial update if you don't pass in all properties. Think of this as a "patch" vs. a replacement update. The key and revision properties are always required.
• Returns the entire entity, including both new and unchanged properties

const person = await myRepo.create({
  name: 'Joe',
  age: 28,
  favoriteColor: 'blue',
});
// Full item update
person.favoriteColor = 'teal';
const newPerson1 = await myRepo.update(person);
console.log(newPerson1.favoriteColor); // 'teal'

// Partial update
const partial = {
  favoriteColor: 'aquamarine',
  key: person.key,
  revision: newPerson1.revision,
};
const newPerson2 = await myRepo.update(partial);
console.log(newPerson2.favoriteColor); // 'aquamarine'
console.log(newPerson2.age); // 28

// More Coming Soon...