tinymo simplifies constructing DynamoDB's JSON-based command inputs.

From this:

const update = {
  TableName: 'users',
  Key: { 
    id: 'bob' 
  },
  UpdateExpression: 'SET #orders :orders',
  ConditionExpression: '#age >= :ageCondition',
  ExpressionAttributeNames: { 
    '#age': 'age', 
    '#orders': 'orders' 
  },
  ExpressionAttributeValues: { 
    ':ageCondition': 18, 
    ':orders': 5
  }
}

To this:

tinymo.update('users', { id: 'bob' }).set('orders', 5).condition('age', '>=', 18)

Installation

npm i @parana-games/tinymo

How to Use

1. Import:

import { tinymo } from '@parana-games/tinymo';

2. Create requests:

tinymo supports all of DocumentClient's requests:

const update = tinymo.update('table', { name: 'John' })
const put = tinymo.put('table', someItem)
const deleteRequest = tinymo.delete('table', { id: 1 })
const get = tinymo.get('table', { id: 'id' })
const batchGet = tinymo.batchGet()
const batchWrite = tinymo.batchWrite()
const query = tinymo.query('table')
const scan = tinymo.scan('table')
const transactGet = tinymo.transactGet()
const transaction = tinymo.transaction()

3. Customize requests:

Request options are accessed through members of the class:

get.attributes('id', 'name')

query.key('sk', '>=', 'order#100').filter('type', '=', 'refund')

scan.consistentRead = true

update.returnValues = 'ALL_NEW'

4. Execute with .run():

Every request is executable with run()

await transaction.run()

const queryResponse = await query.run()

const batchGetResponse = await batchGet.run()

Promise.all([put, update, deleteRequest].map(request => request.run()));

Transactions

There are two ways of adding writes to a transaction:

1. Using the update, put and delete methods:

These methods add the corresponding write item to the list and return it, so you can manipulate and pass it around with ease.

const update = transaction.update('users', { id: 'dan' })
update.add('balance', 10);

transaction.put('users', { id: 'john', balance: 20 });
transaction.delete('orders', { id: '123' });

2. Using the push method, which accepts Write objects.

Write is the base class of Update, Put and Delete.

const writes: Write[] = generateWrites(); 

// Sometimes you have just one update to make, so a transaction is overkill.
if (writes.length > 1) {
  await transaction.push(...writes).run();
} else (writes.length === 0) {
  await writes[0].run(); 
}

Testability

Generate pure DynamoDB JSON-based command inputs with build():

const put = tinymo.put('games', { name: 'pool-stars' });
put.build()

↓

{
  'TableName': 'games',
  'Item': {
    'name': 'pool-stars'
  }
}

Useful for tiny unit tests!

Using without the tinymo Client

Send commands using your DynamoDBClient:

import { Delete } from '@parana-games/tinymo';

const tinymoDelete = new Delete('users', { name: 'john' });
const command = new DeleteCommand(tinymoDelete.build());
const dynamoDBClient = new DynamoDBClient({});
await dynamoDBClient.send(command);

️ Don't use run() when creating tinymo objects with new. They won't have an associated client.

import { Scan } from '@parana-games/tinymo';

const scan = new Scan('users');
await scan.run(); // error thrown as this instance is clientless

Use TinymoClient.setDocumentClient to set your own DocumentClient

TinymoClient.setDocumentClient(myCustomDocumentClient); // Useful when using X-Ray!

Documentation

tinymo aligns strictly with DynamoDB's API, so you can simply refer to its documentation.

Contributing

If you think we've missed something or can do something better, feel free opening an issue or submitting a pull request.