README.md

promise-hook

Installation

Install it with yarn:

yarn add promise-hook

Or with npm:

npm i promise-hook --save

Demo

The simplest way to start playing around with promise-hook is with this CodeSandbox snippet: https://codesandbox.io/s/ykmklm6m21

Simple data fetching

In order to fetch the data, you need to pass a Promise returning function as a first argument to usePromise hook. It will return you back response related payload such as resolved data, request status or the error if it exists.

resolve option is used to initiate data fetching when component mounts.

import React from "react";
import { usePromise } from "promise-hook";

const Movies = () => {
  const { isLoading, data } = usePromise(fetchMovies, { resolve: true });

  return isLoading ? (
    <div>Loading...</div>
  ) : (
    <div>
      {data.map(movie => (
        <div key={movie.id}>{movie.title}</div>
      ))}
    </div>
  );
};

const fetchMovies = () =>
  fetch(`http://your-amazing-api.com/movies`).then(res => res.json());

Passing arguments

In order to pass some arguments to the Promise function, you need to use arrow function wrapper and pass needed argument from a closure.

By default, when resolve option is enabled, data fetching is initiated only on the first render. But you can control it with resolveCondition setting. If an array of variables passed will be changed - data fetching will be initiated again.

import React from "react";
import { usePromise } from "promise-hook";

const Movies = ({ category }) => {
  const { isLoading, data } = usePromise(() => fetchMovies(category), {
    resolve: true,
    resolveCondition: [category]
  });

  return isLoading ? (
    <div>Loading...</div>
  ) : (
    <div>
      {data.map(movie => (
        <div key={movie.id}>{movie.title}</div>
      ))}
    </div>
  );
};

const fetchMovies = category =>
  fetch(`http://your-amazing-api.com/movies/${category}`).then(res =>
    res.json()
  );

Fetching on demand

When you need to send any request on demand instead of component mount, you can use request function returned from the usePromise hook.

After that function is called, data fetching will be started and payload variables such as isLoading etc will be updated accordingly.

import React from "react";
import { usePromise } from "promise-hook";
import { Form, Input, Button } from "./Form";

const SignUp = () => {
  const { isLoading, request } = usePromise(signUp);

  return (
    <Form onSubmit={data => request(data)}>
      <Input type="text" name="full_name" />
      <Input type="text" name="email" />
      <Input type="password" name="password" />
      <Button>{isLoading ? "Signing up..." : "Sign up"}</Button>
    </Form>
  );
};

const signUp = data =>
  fetch(`http://your-amazing-api.com/users`, {
    method: "POST",
    body: data
  }).then(res => res.json());

Error handling

Once the error was happened during the request, an error variable will be populated with the corresponding error object. You can use it afterwards for displaying apropriate error message in the UI.

import React from "react";
import { usePromise } from "promise-hook";

const Movies = () => {
  const { isLoading, data, error } = usePromise(fetchMovies, {
    resolve: true
  });

  return isLoading ? (
    <div>Loading...</div>
  ) : error ? (
    <div>Error loading movies - {error.message}</div>
  ) : (
    <div>
      {data.map(movie => (
        <div key={movie.id}>{movie.title}</div>
      ))}
    </div>
  );
};

const fetchMovies = () =>
  fetch(`http://your-amazing-api.com/movies`).then(res => res.json());

TODO

• Promise cancelling.
• Caching.
• Resetting / Updating response state.
• Middleware support.