如何在初始渲染后重新渲染自定义钩子

Question

I have custom hook named useIsUserSubscribed that checks to see a specific user is subscribed. It returns true if the user is subscribed and false if the user is not subscribed...

import { useState, useEffect } from "react";
import { useSelector } from "react-redux";
import { checkSubscription } from "../services";

// this hook checks if the current user is subscribed to a particular user(publisherId)
function useIsUserSubscribed(publisherId) {
  const [userIsSubscribed, setUserIsSubscribed] = useState(null);
  const currentUserId = useSelector((state) => state.auth.user?.id);

  useEffect(() => {
    if (!currentUserId || !publisherId) return;

    async function fetchCheckSubscriptionData() {
      try {
        const res = await checkSubscription(publisherId);
        setUserIsSubscribed(true);
      } catch (err) {
        setUserIsSubscribed(false);
      }
    }

    fetchCheckSubscriptionData();
  }, [publisherId, currentUserId]);

  return userIsSubscribed;
}

export default useIsUserSubscribed;

...I have a button using this hook that renders text conditionally based on the boolean returned from useIsUserSubscribed ...

import React, { useEffect, useState } from "react";
import { add, remove } from "../../services";
import useIsUserSubscribed from "../../hooks/useIsUserSubscribed";

const SubscribeUnsubscribeBtn = ({profilePageUserId}) => {

  const userIsSubscribed = useIsUserSubscribed(profilePageUserId);
  
  const onClick = async () => {
    if (userIsSubscribed) {
       // this is an API Call to the backend
      await removeSubscription(profilePageUserId);

    } else {
      // this is an API Call to the backend
      await addSubscription(profilePageUserId);
    }
    // HOW CAN I RERENDER THE HOOK HERE!!!!?
  }

  return (
    <button type="button" className="sub-edit-unsub-btn bsc-button" onClick={onClick}>
          {userIsSubscribed ? 'Subscribed' : 'Unsubscribed'}
    </button>
  );
} 

After onClick I would like to rerender my the useIsUserSubscribed hook So that my button text toggles. Can this be done?

Answer 1

Add a dependece on useIsUserSubscribed's useEffect.

hook:

function useIsUserSubscribed(publisherId) {
    const [userIsSubscribed, setUserIsSubscribed] = useState(null);
    const currentUserId = useSelector((state) => state.auth.user?.id);
    // add refresh dependece
    const refresh = useSelector((state) => state.auth.refresh);

    useEffect(() => {
        ...
    }, [publisherId, currentUserId, refresh]);
    ...
}

component:

const onClick = async () => {
    ...
    // HOW CAN I RERENDER THE HOOK HERE!!!!?
    // when click, you can dispatch a refresh flag.
    dispatch(refreshSubState([]))
}

Expose forceUpdate metheod.

hook:

function useIsUserSubscribed(publisherId) {
    const [update, setUpdate] = useState({});
    const forceUpdate = () => {
        setUpdate({});
    }  

    return {userIsSubscribed, forceUpdate};
}

component:

const {userIsSubscribed, forceUpdate} = useIsUserSubscribed(profilePageUserId);

const onClick = async () => {
    ...
    forceUpdate();
}

Answer 2

you can not use useEffect in your hook for that purpose try this:

hook:

function useIsUserSubscribed() {
  const currentUserId = useSelector((state) => state.auth.user?.id);


  const checkUser = useCallback(async (publisherId, setUserIsSubscribed) => {
    if (!currentUserId || !publisherId) return;
      try {
        const res = await checkSubscription(publisherId);
        setUserIsSubscribed(true);
      } catch (err) {
        setUserIsSubscribed(false);
      }
    
  }, [currentUserId]);

  return {checkUser};
}

export default useIsUserSubscribed;

component:

const SubscribeUnsubscribeBtn = ({profilePageUserId}) => {
    const [userIsSubscribed,setUserIsSubscribed]=useState(false);
    const { checkUser } = useIsUserSubscribed();

     useEffect(()=>{
        checkUser(profilePageUserId,setUserIsSubscribed)
     },[checkUser,profilePageUserId]);
  
  const onClick = async () => {
    if (userIsSubscribed) {
       // this is an API Call to the backend
      await removeSubscription(profilePageUserId);

    } else {
      // this is an API Call to the backend
      await addSubscription(profilePageUserId);
    }
    // HOW CAN I RERENDER THE HOOK HERE!!!!?
    checkUser(profilePageUserId,setUserIsSubscribed)
  }

  return (
    <button type="button" className="sub-edit-unsub-btn bsc-button" onClick={onClick}>
          {userIsSubscribed ? 'Subscribed' : 'Unsubscribed'}
    </button>
  );
} 

you can also add some loading state in your hook and return them too so you can check if process is already done or not

Answer 3

Here is another solution by user @bitspook

SubscribeUnsubscribeBtn has a dependency on useIsUserSubscribed , but useIsUserSubscribed don't depend on anything from SubscribeUnsubscribeBtn . Instead, useIsUserSubscribed is keeping a local state. You have a couple of choices here:

1. Move the state regarding whetehr user is subscribed or not one level up, since you are using Redux, perhaps in Redux.
2. Communicate to useIsUserSubscribed that you need to change its internal state.

For 1)

  const [userIsSubscribed, setUserIsSubscribed] = useState(null);

move this state to Redux store and use it with useSelector.

For 2) , return an array of value and callback from the hook, instead of just the value. It will allow you to communicate from component back into the hook.

In useIsUserSubscribed ,

  return [userIsSubscribed, setUserIsSubscribed];

Then in onClick , you can call setUserIsSubscribed(false) , changing the hook's internal state, and re-rendering your component.