是否可以在本机反应中从另一个 class 组件访问 useRef 变量？

Question

I am attempting to access a useRef variable declared in my functional component in a class component. Is this possible? Currently when I import the functional component, DetailsScreen, below in my class component, FireMessage, and add console.log(DetailsScreen.receiverUid) in the get db() function it returns 'undefined'. Do you know what may be causing this and how I can gain access to this variable in a class component?

**DetailsScreen**


import 'react-native-gesture-handler';

import { Image, StyleSheet, Text, TouchableOpacity, View, ScrollView, 
SafeAreaView, FlatList, Alert, TouchableHighlight, Platform, Dimensions, 
Linking} from 'react-native';

import React, {useState, useContext, useRef} from 'react';


const DetailsScreen = ({route, navigation}) => {

    const receiverUid = useRef(route.params.key);
}


export default DetailsScreen;


**FireMessage**

import firebase from "firebase";
import firebaseConfig from './firebaseConfig.js';
import 'react-native-gesture-handler';
import * as React from 'react';
import DetailsScreen from './DetailsScreen.js';

class FireMessage {

 constructor() {
   this.init()
   this.checkAuth() 
 }

 init = () => {
   if (!firebase.apps.length && firebaseConfig.apps.length === 0) {
   firebase.initializeApp({
    apiKey: "xxxxxxxxxxx",
    authDomain: "xxxxxxxxxxx",
    databaseURL: "xxxxxxxxxx",
    projectId: "xxxxxxxx",
    storageBucket: "xxxxxxxxxx",
    messagingSenderId: "xxxxxxxx",
    appId: "xxxxxxxxxxx",
    measurementId: "xxxxxxxxx"
   });
  }
};

checkAuth = () => {
  firebase.auth().onAuthStateChanged(user => {
    if (!user) {
      firebase.auth().signInAnonymously();
    }
  });
};

send = messages => {
  messages.forEach(item => {
    const message = {
      text: item.text,
      timestamp: firebase.database.ServerValue.TIMESTAMP,
      user: item.user
    };

   this.db.push(message)
 });
};

parse = message => {
   const { user, text, timestamp } = message.val();
   const { key: _id } = message;
   const createdAt = new Date(timestamp);


   return {
    _id,
    createdAt,
    text,
    user
   };
};

get = callback => {
   this.db.on("child_added", snapshot => 
   callback(this.parse(snapshot)));
};

off() {
   this.db.off();
}

get db() {
   console.log(DetailsScreen.receiverUid)
   return firebase.database().ref("messages");
}

get uid() {
   return (firebase.auth().currentUser || {}).uid;
}
}

export default new FireMessage();

Answer 1

Whenever your update receiverUid update DetailsScreen.receiverUid

const newId = 'some-receiver-id'
receiverUid.current = newId
DetailScreen.receiverUid = newId