@twolions/warmer-backend-utilities

Collection of common NodeJS utilities used in Warmer's backend services

Installation

npm i -S @twolions/warmer-backend-utilities

API

AMQPClient

Used to send and receive messages from a RabbitMQ broker.

AMQPClient expects RABBITMQ_URL and RABBITMQ_DLX to be defined in process.env.

Arguments

queue: string

The name of the queue to connect to.

Usage

const { AMQPClient } = require('@twolions/warmer-backend-utililies');

const client = new AMQPClient('<queue>');

// send a message to the queue
await client.send({ type: 'email:send', payload: {...} });

// receive messages from queue
//
// this is a process that last for the duration of the process itself; if you want to use it along with other processes (http server, etc...) do not `await client.receive`.
await client.receive((msg) => { ... });

// acknowledge a message
client.ack(msg);

// reject a message
// if requeue is false, messages will end up in DLQ, otherwise they will be sent back to the queue where they were consumed from
client.reject(msg, opts = { requeue = false });

// close connection
await client.close();

validateRequest

A Koa middleware to validate ctx.query, ctx.params, ctx.body.

validateRequest uses ajv under the hood to perform validations (defined with JSON Schema).

Arguments

schema: object

A Simplified representation of a JSON Schema:

• Keys can be suffixed with a '?' to denote them as optional
• By default, objects will have additionalProperties: false set; you can override this by having '*': true
• All objects will have a required array, with the keys of non-optional fields
• To create an array type, have the value of a key be an array with a single object, which is the description of the array items
• Has support for nested objects

Return value

void

Usage

const { validateRequest } = require('@twolions/warmer-backend-utilities')

router.post(
  '/',
  validateRequest({
    params: {
      id: { type: 'string', minLength: 1 }
    },
    body: {
      'optional?': { type: 'string' }
      nested: {
        type: { type: 'string', minLength: 1 },
        'count?': { type: 'number', minLength: 1 },
      },
    },
  }),
  async (ctx) => {
    const { id } = ctx.request.params;
    const { optional, nested } = ctx.request.body;

    // optional and nested.count can be `null`
  },
)

validate

A function that uses the same simplified representation of a JSON Schema as validateRequest, but to validate any value you might require.

Arguments

schema: object

A Simplified representation of a JSON Schema:

value: any

The value to validate against schema

Return value

{
  valid: Boolean,
  errors: Array,
}

Usage

const { validate } = require('@twolions/warmer-backend-utilities')

sleep

⏰ async function

Returns a promise that resolves after ms miliseconds.

Arguments

ms: int

Number of miliseconds to wait before resolving promise

Return value

void

Usage

await sleep(1000); // will wait one second before resolving

retry

⏰ async function

Arguments

fn: function

Function to retry.

opts: object

Configuration options. Defaults to 3 attempts with no delay.

{
  attempts: 3,
  delay: 0,
}

Return value

Whatever the return value of fn argument is.

Throws if attempts are reached without fn resolving.

Usage

await retry(possiblyFailingFunction, { attempts: 10, delay: 100 });