I'm coding in React Native and need to get a value from Google Firebase in real time. I am able to get the value (1), but when the value in the database changes, the textbox in my application does not change accordingly (2). In other words, real-time synchronization with the database is not implemented. I can't figure out why. Will you help me with this problem? Thank you so much! The code I wrote is as follows:
import React, { useState } from 'react'; import { View, Text,
TextInput} from 'react-native'; import { NavigationContainer } from
'@react-navigation/native'; import { createNativeStackNavigator } from
'@react-navigation/native-stack'; import { ImageBackground,
StyleSheet, Pressable, Image } from 'react-native'; import { Slider }
from '@react-native-assets/slider' import { Linking } from
'react-native' import database from '@react-native-firebase/database';
var Data = "";
function Room({ navigation, route }) {
//(1)
database()
.ref('/esp01_1/id')
.on('value', snapshot => {
console.log('data from firebase: ', snapshot.val());
Data = snapshot.val()
});
return (
<View style={styles.container}>
//(2)
<Text style={styles.text}>{Data}</Text>
</View> ); }
I need to get a value from Google Firebase in real time, and when it changes in the database, I need it to change in the textbox as well.
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This is because data is loaded from Firebase (and pretty much any modern cloud API) asynchronously, and is not yet available when your
<Text style={styles.text}>{Data}</Text>is executed.You'll want to:
The common way to do this is by using the
useStateanduseEffecthooks.const [data, setData] = useState(); // Putting the code to load from Firebase in a useEffect call // with no dependencies (the empty array at the end) ensure it // only runs once, when the component is first rendered. useEffect(() => { database() .ref('/esp01_1/id') .on('value', snapshot => { // Calling setData puts the data in the component's state // and tells ReactJS to rerender the UI. setData(snapshot.val()); }); }, []);This is a quite complex topic, so I recommend reading up on both of the hooks used here and also see: