Advanced Fetch

Wrapper for native fetch which provides advanced functionality, such as:

• Cached Request
• Version Cached Request
• Delayed Requests

Cached Response

Make a reqeust to server, in a case if device is offline, and this request was done before lib will provide you with cached response, for example:

import { cachedFetch, NoCacheForRequestError } from 'react-native-advanced-fetch';

cachedFetch(url, params)
    .then(res => {
      if (res.cached) {
        // do something if response is cached (because of offline device status)
      }
    
      return res.json()
    }) // for now it works only with json
    .then(data => {
        // do work, data will be data from server or cached data if device is offline
    })
    .catch(err => {
        // err will be instance of NoCacheForRequestError if device is offline and no cache is not available
    })

Version Cached Response

Make a reqeust to server, in a case if:

• device is online - first request will be done to the version endpoint (versionUrl param for versionCachedFetch), this endpoint should return just version of data (basically it's hash of data, so if data changes this hash should also change) in a format: {version: 2}. If version is different with cached previous response version, then request to a data endpoint will be made (response should contain version field, for example {version: 2, firstName: 'John', lastName: 'Doe'}) but if version is same with cached version than cached version will be returned and no request to data endpoint will be made
• device is offline - behaviour will be same with cachedFetch

import { versionCachedFetch, NoCacheForRequestError } from 'react-native-advanced-fetch';

versionCachedFetch(url, params, versionUrl)
    .then(res => res.json()) // for now it works only with json
    .then(data => {
        // do work, data will be data from server if device is online and version is different with cached response, or cached data if device is offline, in a case if device is offline it will be cached data
    })
    .catch(err => {
        // err will be instance of NoCacheForRequestError if device is offline and no cache is not available
    })

Delayed Request

Make a request to a server, and if device is offline this request will be saved and executed when device becomes online, for example:

import { init, delayedFetch, DelayedRequestError } from 'react-native-advanced-fetch';

init({
    onProcessedDelayedRequest: (request) => {
        // this cb will be executed when delayed request finally processed in background
    },
    startDelayedRequestWorker: true // you should run init with this option before delayedFetch requests, it will initialize background worker for delayed requests
}); 

delayedFetch(url, params)
    .then(res => res.json()) // for now it works only with json
    .then(data => {
        // do work, data will be data from server
    })
    .catch(err => {
        // err will be instance of DelayedRequestError if device is offline and request is delayed, but anyway this request will be inserterd to query and executed when device becomes online
    })

Settings

To pass any settings you need to call init method and pass settings there:

import { init } from 'react-native-advanced-fetch';

init({
    fetch: fetch, // fetch instance which is used for request
    waitingForConnectionChangeInterval: 100, // lib will check is device is online or offline with this interval, normally you don't need to pass this setting
    beforeSendDelayedRequest: (request) => {
        return request; // this cb will executed when right before request fetch, you can modify request here (you need to return modified request) or cancel it (just return null)
    },
    onProcessedDelayedRequest: (request) => {
        // this cb will be executed when delayed request finally processed in background
    },
    delayedRequestLifetime: Infinity, // delayed requests lifetime,
    onExceededDelayedRequestLifetime: (request) => {
        // this cb will be executed when delayed request exceed it lifetime and will not be processed 
    },
    startDelayedRequestWorker: false, // process delayed requests in background
    onOnlineOfflineStatusChange: (cb) => {
      cb(status) // you need to call cb with new status (boolean) in a case if you have custom logic for online/offline change strategy, by default `NetInfo.isConnected.addEventListener('connectionChange', cb)` is used to findout is device online/offline (by default it's offline so you need to call this cb to change status)
    }
}); 

Note

You should include ACCESS_NETWORK_STATE, READ_EXTERNAL_STORAGE, WRITE_EXTERNAL_STORAGE permission on Android