Cancel a fetch request in react-native

Question

Is there any way to abort a fetch request on react-native app ?

class MyComponent extends React.Component {
  state = { data: null };

  componentDidMount = () =>
    fetch('http://www.example.com')
      .then(data => this.setState({ data }))
      .catch(error => {
        throw error; 
      });

  cancelRequest = () => {
   //???
  };

  render = () => <div>{this.state.data ? this.state.data : 'loading'}</div>;
}

i tried the abort function from AbortController class but it's not working !!

...
abortController = new window.AbortController();

cancelRequest =  () => this.abortController.abort();

componentDidMount = () =>
        fetch('http://www.example.com', { signal: this.abortController.signal })
          ....

Any help please !

Solution 1

the best solution is using rxjs observables + axios/fetch instead of promises, abort a request => unsubscribe an observable :

import Axios from "axios";
import {
    Observable
} from "rxjs";

export default class HomeScreen extends React.Component {
    subs = null;

    doStuff = () => {
        let observable$ = Observable.create(observer => {
            Axios.get('https://jsonplaceholder.typicode.com/todos', {}, {})
                .then(response => {
                    observer.next(response.data);
                    observer.complete();
                })
        });

        this.subs = observable$.subscribe({
            next: data => console.log('[data] => ', data),
            complete: data => console.log('[complete]'),
        });

    }

    cancel = () =>
        if (this.subs) this.subs.unsubscribe()

    componentWillUnmount() {
        if (this.subs) this.subs.unsubscribe();
    }

}

That is it :)

Solution 2

You don't need any polyfill anymore for abort a request in React Native 0.60 changelog

Here is a quick example from the doc of react-native:

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 * @flow
*/

'use strict';

const React = require('react');
const {Alert, Button, View} = require('react-native');

class XHRExampleAbortController extends React.Component<{}, {}> {
  _timeout: any;

  _submit(abortDelay) {
    clearTimeout(this._timeout);
    // eslint-disable-next-line no-undef
    const abortController = new AbortController();
    fetch('https://facebook.github.io/react-native/', {
      signal: abortController.signal,
    })
      .then(res => res.text())
      .then(res => Alert.alert(res))
      .catch(err => Alert.alert(err.message));
    this._timeout = setTimeout(() => {
          abortController.abort();
    }, abortDelay);
  }

  componentWillUnmount() {
    clearTimeout(this._timeout);
  }

  render() {
    return (
      <View>
        <Button
          title="Abort before response"
          onPress={() => {
            this._submit(0);
          }}
        />
        <Button
          title="Abort after response"
          onPress={() => {
            this._submit(5000);
          }}
        />
      </View>
    );
  }
}

module.exports = XHRExampleAbortController;

Solution 3

I've written quite a bit actually about this subject. You can also find the first issue about the OLD lack of AbortController in React Native opened by me here

The support landed in RN 0.60.0 and you can find on my blog an article about this and another one that will give you a simple code to get you started on making abortable requests (and more) in React Native too. It also implements a little polyfill for non supporting envs (RN < 0.60 for example).

Comments

[AHmedRef]

this is not working, i get this error message : Possible Unhandled Promise Rejection (id: 0): [AbortError: Aborted]

[Nainal]

From the docs:- This "polyfill" doesn't actually close the connection when the request is aborted, but it will call .catch() with err.name == 'AbortError' instead of .then()

[hfossli]

That does not cancel the underlying axios request. Just the subscription to the result.

[mixdev]

It's actually better to put the code here and additionally add a link to your article for more in-depth understanding.