Introduction

universal-data-loader is a library that aims to make data fetching easier to manage in React application. You can easily manage cache, integrate with data persisters(such as localStorage), configure fetching behaviours. It works with redux + redux-saga or the new React Context API

Getting started

Install

$ npm i universal-data-loader --save

Usage Example

step 1: say you have an api call

// an api call is simply a function that returns promise
type ApiCall = (args: any) => Promise<any>;

Let's create a mock api call which returns a random number in 1000ms

const mockApi = () => {
  return new Promise((resolve) => {
    setTimeout(() => resolve(Math.random()), 1000)
  })
}

step 2: use DataLoader component

import { DataLoader } from 'universal-data-loader'
// if you are using redux and redux-saga, import this one:
import { ReduxDataLoader as DataLoader } from 'universal-data-loader'

export const App = () =>
  <DataLoader name="randomNumber" apiCall={mockApi}>
  {
    (loader) => {
      if (loader.loading) {
        return <div>loading...</div>
      }
      if (loader.error) {
        return <div>Error!!!</div>
      }
      return <div>{loader.data ? loader.data : 'No Data!'}</div>
    }
  }
  </DataLoader>

The loader that child function gets as parameter:

// data: the data you get from the api call
// loading: the load status, `true` when api call is running
// error: the Error throw from api call
// lastUpdateTime: the last time that data was loaded from api call
// lastErrorTime: the last time that data fetching throw an error
// load: call this function to manually start to load data
interface Loader<T = any> {
  data: T | null
  loading: boolean
  error: Error | null
  lastUpdateTime?: number
  lastErrorTime?: number
  load: () => void;
}

Step 3: If you are using React >= 16.4.0 with the new Context API

import { DataProvider } from 'universal-data-loader'

ReactDOM.render(
  <DataProvider>
    <App />
  </DataProvider>,
  document.getElementById('root')
)

(Step 3): If you are using redux and redux-saga

import {
  dataLoaderSagas, 
  dataLoaderReducer, 
  DATA_LOADER_NAMESPACE, 
} from 'universal-data-loader'

// combine dataLoaderReducer with your own reducers and give it the name: DATA_LOADER_NAMESPACE
const reducers = combineReducers({
  [DATA_LOADER_NAMESPACE]: dataLoaderReducer,
})

// run sagas with dataLoaderSagas
sagaMiddleware.run(dataLoaderSagas)