README.md

RemoteData

Typesafe library for representation loadable state.

In web development from project to project, we constantly encounter asynchronous data. The implementation of the loadable falls on the shoulders of the developer and is sometimes redundant: we come up with additional state fields and duplicate the code. RemoteData helps to describe a type-safe data source with the necessary states and provides the minimum required set of functions for processing

type RemoteData<E, D> = NotAsked | Loading | Reloading | Success<D> | Failure<E>;

Installation

npm i @young-aviator-club/remote-data

Examples

Example	Link
JS + React	Codesandbox
TS + React	Codesandbox
TS + React + Mobx	Codesandbox
TS + React + Mobx (extended)	Codesandbox
JS + React + redux-toolkit .	Codesandbox: Before -> After

More examples coming soon!

Basic usage

import * as RD from '@young-aviator-club/remote-data';

let loadableResource: RD.RemoteData<Error, number> = RD.notAsked();

const loadResource = () => {
  console.log((loadableResource = RD.loading()));
  setTimeout(() => {
    console.log((loadableResource = RD.success(10)));
  }, 2000);
};

console.log(loadableResource);

API

Guards

• RD.isNotAsked(rd)
• RD.isLoading(rd)
• RD.isReloading(rd)
• RD.isSuccess(rd)
• RD.isFailure(rd)

import * as RD from '@young-aviator-club/remote-data';

let loadableResource: RemoteData<Error, number> = RD.notAsked(); // or another

if (RD.isNotAsked(loadableResource)) {
  console.log('No state is NOT_ASKED');
}

loadableResource = RD.loading();

if (RD.isLoading(loadableResource)) {
  console.log('No state is LOADING');
}

loadableResource = RD.failure(new Error('error'));

if (RD.isFailure(loadableResource)) {
  // typesafe access to error
  console.log('Failure!', loadableResource.error.message); // "error"
}

loadableResource = RD.success(100);

if (RD.isSuccess(loadableResource)) {
  // typesafe access to data
  console.log('Success', loadableResource.data); // 100
}

Working with array of RemoteData

import * as RD from '@young-aviator-club/remote-data';

let loadableResource1: RemoteData<Error, number> = RD.notAsked();
let loadableResource2: RemoteData<Error, number> = RD.notAsked();

if (RD.isNotAsked([loadableResource1, loadableResource2])) {
  console.log('Now states is NOT_ASKED');
}

loadableResource1 = RD.loading(); // only one resouce in loading state

if (RD.isLoading([loadableResource1, loadableResource2])) {
  // loadableResource1 = LOADING, loadableResource2 = NOT_ASKED
  // in this case array of RemoteData is LOADING
  console.log('Now states is LOADING');
}

loadableResource2 = RD.failure(new Error('error'));

if (RD.isFailure([loadableResource1, loadableResource2])) {
  // if some resource is failed - array of RemoteData is failed
  console.log('Failure!');
}

loadableResource1 = RD.success(1);
loadableResource2 = RD.success(2);

if (RD.isSuccess([loadableResource1, loadableResource2])) {
  // if each RemoteData in array is SUCCESS - true
  console.log('Success', loadableResource1.data + loadableResource2.data); // 3
}

Error handling / accessor

• RD.successOrElse(rd, orElse)

import * as RD from '@young-aviator-club/remote-data';

let loadableResource: RemoteData<Error, number> = RD.notAsked(); // or another

console.log(RD.successOrElse(loadableResource, () => -1)); // -1

loadableResource = RD.success(100);

console.log(RD.successOrElse(loadableResource, () => -1)); // 100

// for array of RemoteData

let loadableResource1: RemoteData<Error, number> = RD.notAsked();
let loadableResource2: RemoteData<Error, number> = RD.notAsked();

console.log(RD.successOrElse([loadableResource1, loadableResource2], () => -1)); // -1

loadableResource1 = RD.success(1);

// -1 because second RemoteData is NOT_ASKED
console.log(RD.successOrElse([loadableResource1, loadableResource2], () => -1)); // -1

loadableResource2 = RD.success(2);

console.log(RD.successOrElse([loadableResource1, loadableResource2], () => -1)); // [1, 2]

Pattern matching

• RD.fold(rd, handlers)

import * as RD from '@young-aviator-club/remote-data';

let loadableResource: RemoteData<Error, number> = RD.notAsked();

const handleState = (rd: RemoteData<Error, number>) => {
  return RD.fold(rd, {
    notAsked: () => 'no data',
    loading: () => 'loading...',
    reloading: () => 'reloading...',
    success: (num) => `result: ${num}`,
    failure: (err) => `error: ${err.message}`,
  });
};

handleState(loadableResource); // "no data"

loadableResource = RD.loading();
handleState(loadableResource); // "loading..."

loadableResource = RD.reloading();
handleState(loadableResource); // "reloading..."

loadableResource = RD.failure(new Error('error'));
handleState(loadableResource); // "error: error"

loadableResource = RD.success(2);
handleState(loadableResource); // "result: 2"

with array of RemoteData:

import * as RD from '@young-aviator-club/remote-data';

let loadableResource1: RemoteData<Error, number> = RD.notAsked();
let loadableResource2: RemoteData<Error, number> = RD.notAsked();

const handleState = (rds: RemoteData<Error, number>[]) => {
  return RD.fold(rds, {
    notAsked: () => 'no data',
    loading: () => 'loading...',
    reloading: () => 'reloading...',
    success: ([num1, num2]) => `result: ${num1 + num2}`,
    failure: ([err1, err2]) => `errors: ${err1.message}, ${err2.message}`,
  });
};

handleState(loadableResource); // "no data"

loadableResource1 = RD.loading();
loadableResource2 = RD.loading();
handleState(loadableResource); // "loading..."

loadableResource1 = RD.failure(new Error('error1'));
loadableResource2 = RD.failure(new Error('error2'));
handleState(loadableResource); // "errors: error1, error2"

loadableResource1 = RD.success(1);
loadableResource2 = RD.success(2);
handleState(loadableResource); // "result: 3"