将 useEffect 钩子与“异步”一起使用

Question

How to clean up react request in react hooks. I read that in need to enter in my hook AbortController but I don't know how. I using next.js. What are best methods to eliminate this problem? And I get this warning:

Warning: can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.

This is my custom hook to fetch data:

import { useState, useEffect, useCallback } from 'react'
import { MOVIE_API_URL, MOVIE_KEY } from '../../config'

export const useMovieDetailsFetch = (movieId) => {
  const [state, setState] = useState({})
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState(false)

  const fetchData = useCallback(async () => {
    setError(false)
    setLoading(true)

    try {
      const movieDetailsEndpoint = `${MOVIE_API_URL}movie/${movieId}?api_key=${MOVIE_KEY}`
      const result = await (await fetch(movieDetailsEndpoint)).json()
      const creditsEndpoint = `${MOVIE_API_URL}movie/${movieId}/credits?api_key=${MOVIE_KEY}`
      const creditsResult = await (await fetch(creditsEndpoint)).json()
      // Filtring in crew for directors only
      const movieDirectors = creditsResult.crew.filter(
        (member) => member.job === 'Director'
      )

      setState({
        ...result,
        movieDirectors,
        actors: creditsResult.cast,
      })
    } catch (error) {
      setError(true)
    }
    setLoading(false)
  }, [movieId])

  useEffect(() => {
   
    fetchData()
  }, [fetchData])

  return [state, loading, error]
}

Answer 1

Using an abort controller , in its rawest form:

const controller = new AbortController();
const { signal } = controller;
...

fetch(url, { signal });

...
// abort
controller.abort();

To abort an in-flight fetch in effect hook

useEffect(() => {
  const controller = new AbortController();
  const { signal } = controller;
  fetch(url, { signal });

  return () => {
    controller.abort(); // abort on unmount for cleanup
  };
}, []);

I found this article very informative when I needed to develop a way to cancel fetch requests.

Edit

The signal needs to be added to the fetch requests options object. You can also define the async fetchData function inside the effect (this is normal), so it's all enclosed in the effect hook's callback scope.

export const useMovieDetailsFetch = (movieId) => {
  const [state, setState] = useState({})
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState(false)

  useEffect(() => {
    const controller = new AbortController();
    const { signal } = controller;

    const fetchData = async () => {
      setError(false);
      setLoading(true);

      try {
        const movieDetailsEndpoint = `${MOVIE_API_URL}movie/${movieId}?api_key=${MOVIE_KEY}`;
        const result = await (
            await fetch(movieDetailsEndpoint, { signal })
          ).json();
        const creditsEndpoint = `${MOVIE_API_URL}movie/${movieId}/credits?api_key=${MOVIE_KEY}`;
        const creditsResult = await (
            await fetch(creditsEndpoint, { signal })
          ).json();
        // Filtring in crew for directors only
        const movieDirectors = creditsResult.crew.filter(
          (member) => member.job === 'Director'
        );

        setState({
          ...result,
          movieDirectors,
          actors: creditsResult.cast,
        });
      } catch (error) {
        setError(true);
      }
      setLoading(false);
    }

    fetchData();

    return () => controller.abort();
  }, [movieId]);

  return [state, loading, error];
}