Deasyncify

A declarative way of doing asynchronous programing with Typescript.

Overview

• Getting started
• Issues
• Installation
• Usage
• Methods
  • watch
  • watchAll
  • watchSettled

Getting started

Deasyncify is a utility library which builds on top of Typescript's Promise api and simplifies handling promises and async functions. The goal of this library is to help make handling asychronous Typescript code more declarative withoud having to wrap code in a try-catch blockcode (which makes your code more cleaner) and without losing type definition on the return types of the values of resolved promises or async function trying to write a custom wrapper for yourself (yes we implemented that too). Imagine writing your own custom async wrapper for every single new project (that's pretty much a drag).

import axios from 'axios';
import Deasyncify from 'deasyncify';

const doSomething = async () => {
    const [expectedValue, error] = await Deasyncify.watch(axios.get(url))

    if(error) throw error

    return expectedValue
}

Issues

This library is meant to work on all nodejs enviroments. If any issue or bug is found in whatever enviroment you are on, feel free to report it to issues and we'll address it as fast as we can.

Installation

Using yarn

$ yarn add deasyncify

Using npm

$ npm install deasyncify

Usage

Deasyncify is a utility class which currenctly comprises of watch, watchAll and watchSettled methods which we'll look into below

Methods

watch

Deasyncify.watch is used to handle a single asynchorous function or promise.

Definitions

• watch = <T> (asynParam: Promise<T> | (() => Promise<T>)) => Promise<[T | null, any]>
• Args
  • asyncParam: Promise<T> | (() => Promise<T>)
• Expected output:
  • expectValue: T | null
  • error: any

usage

watch takes in on argument (which could be either a promise or an async function or a function that returns a promise) executes it and returns an array of two values; expectedValue and error. expectedValue being the value return from your asynchronous code (you can name this anything) and error being any errors which running your asynchronous code (you can name this anything as well). error would be undefined if the asyncParam runs successfully but if asyncParam fails, error would be defined an expectedValue would be undefined.

Example

import { Request, Response, Next } from "express";
import prisma from "prisma";
import Deasyncify from "deasyncify";

export const getUser = async (req: Request, res: Response, next: Next) => {
    const [user, userFindError] = await Deasyncify.watch(this.prisma.users.findOne({
        where: { userId: req.user.id }
        }));

    if(userFindError) return next(userFindError);

    res.json(user);
};

watchAll

Deasyncify.watchAll is used to handle a bunch of asynchorous function or promise "concurrently".

Definitions

•  watchAll = <
    J,
    T extends Awaited<J>,
    G = T extends () => any ? Awaited<ReturnType<T>> : T> (asyncArr: J[]) => Promise<[G[] | null, any]>
  

• Args

  • asyncParam: (Promise<T> | (() => Promise<T>))[]

• Expected output:

  • expectValues: T[] | null
  • error: any

usage

watchAll takes in on argument (which could be an array of an asyncParam (a promise or an async function or a function that returns a promise)) executes it and returns an array of two values; expectedValue and error. expectedValues being the value return from your asynchronous code (you can name this anything) and error being any error that occur while running your asynchronous code (you can name this anything as well). if any of the asyncParam in the arr fails, expectedValues would be null and error would be defined. An alternative to this is watchSettled method which doesn't have this behaviour.

Example

import { Request, Response, Next } from "express";
import prisma from "prisma";
import Deasyncify from "deasyncify";

export const getUserItems = async (req: Request, res: Response, next: Next) => {
    const [userItems, userItemsFindError] = await Deasyncify.watchAll([
        this.prisma.cars.findOne({where: { ownersId: req.user.id } }),
        this.prisma.phones.findOne({ where: { ownersId: req.user.id }}),
        this.prisma.pets.findOne({ where: { ownersId: req.user.id }})
        ]);

    if(userFindError) return next(userItemsFindError);

    res.json(userItems);
};

watchSettled

Deasyncify.watchSettled is used to also handle a bunch of asynchorous function or promise "concurrently".

Definitions

•  watchSettled = <
    J,
    T extends Awaited<J>,
    G = T extends () => any ? Awaited<ReturnType<T>> : T> (asyncArr: J[]) => Promise<[G[], any[]]>
  

• Args

  • asyncParam: (Promise<T> | (() => Promise<T>))[]

• Expected output:

  • expectValues: T[] | null
  • errors: any[]

usage

watchAll takes in on argument (which could be an array of an asyncParam (a promise or an async function or a function that returns a promise)) executes it and returns an array of two values; expectedValue and error. expectedValues being the value return from your asynchronous code (you can name this anything) and error being an arr of errors which running your asynchronous code (you can name this anything as well). unlike watchAll which fails if one of the asyncArr elems fail during execution, since watchSettled using Promise.allSettled under the hood, expectedValues would contain all the values of the settled asyncParams and errors would contain all errors if any.

Example

import { Request, Response, Next } from "express";
import prisma from "prisma";
import Deasyncify from "deasyncify";

export const getUserItems = async (req: Request, res: Response, next: Next) => {
    const [userItems, userItemsFindError] = await Deasyncify.watchSettled([
        this.prisma.cars.findOne({where: { ownersId: req.user.id } }),
        this.prisma.phones.findOne({ where: { ownersId: req.user.id }}),
        this.prisma.pets.findOne({ where: { ownersId: req.user.id }})
        ]);

    if(userItemsFindError.length > 0) return next(userItemsFindError);

    res.json(userItems);
};