如何在初始渲染后重新渲染自定義鉤子

我有useIsUserSubscribed一個名為的自定義鉤子，用于檢查是否訂閱了特定用戶。如果用戶已訂閱，則回傳 true，如果用戶未訂閱，則回傳 false...

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;

...我有一個使用這個鉤子的按鈕，它根據從useIsUserSubscribed...回傳的布林值有條件地呈現文本

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>
  );
} 

在onClick我想重新渲染我的useIsUserSubscribed鉤子以便我的按鈕文本切換之后。這能做到嗎？

uj5u.com熱心網友回復：

你不能為此目的在你的鉤子中使用 useEffect 試試這個：

鉤 ：

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;

成分 ：

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>
  );
} 

您還可以在鉤子中添加一些加載狀態并回傳它們，以便您可以檢查行程是否已經完成

uj5u.com熱心網友回復：

添加對 useIsUserSubscribed 的 useEffect 的依賴。

鉤 ：

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]);
    ...
}

成分 ：

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

暴露 forceUpdate 方法。

鉤 ：

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

    return {userIsSubscribed, forceUpdate};
}

成分 ：

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

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

標籤：javascript 反应 反应钩子 反应功能组件

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