我刚开始反应，我在尝试从 Firestore 获取数据字段以显示在我的应用程序的屏幕上时遇到了很多问题

Question

I am going to include photos as well as my code. I do not know what I am doing wrong but I wanna be able to print the current user's name on their profile page as shown in pictures. Thanks so much! It seems as if it is never getting to the snapshot to try to retrieve the fields to where they can be used. I've been stuck on this for going on a week now and do not know what else to try. I feel like it is an easy fix that I am missing but cannot pinpoint what it is.

Firestore picture

App picture

    import 'react-native-gesture-handler';
import auth, {firebase} from '@react-native-firebase/auth';
import firestore from '@react-native-firebase/firestore';
//import * as React from 'react';
import React, {useState} from 'react';

import {NavigationContainer} from '@react-navigation/native';
import {
  StyleSheet,
  Picker,
  SafeAreaView,
  Text,
  View,
  TextInput,
  TouchableOpacity,
  Button,
} from 'react-native';
import {createStackNavigator} from '@react-navigation/stack';
import {ScrollView} from 'react-native-gesture-handler';

const Profile = ({navigation}) => {
  const [firstName, setFname] = useState('');
  const [lastName, setLname] = useState('');
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [age, setAge] = useState('');
  const [sex, setSex] = useState('');
  const [id, setId] = useState('');

  getUserInfo = async () => {
     firebase
      .firestore()
      .collection('users')
      .doc(firebase.auth().currentUser.uid)
      .onSnapshot((docs) => {
        setFname(docs.data().firstName);
        console.log(firstName);
        setLname({lastName: docs.data().lastName});
        setEmail({email: docs.data().email});
        setPassword({password: docs.data().password});
        setAge({age: docs.data().age});
        setSex({sex: docs.data().sex});
        setId({id: docs.data().id});
      });
  };

  

  const db = firebase.firestore();
  var user = firebase.auth().currentUser;
  var usersEmail = user.email;
  var userID = firebase.auth().currentUser.uid;


  
  
  db.collection('users')
    .where('email', '==', usersEmail)
    .get()
    .then(function (querySnapshot) {
      querySnapshot.forEach(function (doc) {
        // doc.data() is never undefined for query doc snapshots
        console.log(doc.id, ' => ', doc.data());
        var data = doc.data();
        const fn = doc.get('firstName');
        setFname({firstName: fn});
        console.log(firstName);
        console.log(data);
        setFname(data.firstName);
        //var lastName = data.lastName;
        //var firstName = doc.get("first");
        //var lastName = doc.get("last");
      });
    })
    .catch(function (error) {
      console.log('Error getting documents: ', error);
    });

    
    
 

  return (
    
    <SafeAreaView style={styles.container2}>
      <ScrollView>
        <View style={styles.container}>
          <Text style={styles.logo}>Profile</Text>
          <Text style={styles.Info}>
            Name: {firstName} {lastName}  
          </Text>
          <Text style={styles.Info}>Email: {usersEmail}</Text>
          <Text style={styles.Info}>Age: </Text>
          <Text style={styles.Info}>Sex:</Text>
          <Text style={styles.Info}>Sports:</Text>
          <TouchableOpacity
            style={styles.button}
            onPress={() => navigation.navigate('EditProfile')}>
            <Text style={styles.buttonText}>Edit Profile</Text>
          </TouchableOpacity>

          <TouchableOpacity
            style={styles.button}
            onPress={() => navigation.navigate('Messages')}>
            <Text style={styles.buttonText}>My Messages</Text>
          </TouchableOpacity>
        </View>
      </ScrollView>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#2c9f45',
    alignItems: 'center',
    justifyContent: 'center',
  },
  container2: {
    flex: 1,
    backgroundColor: '#2c9f45',
    justifyContent: 'center',
  },
  button: {
    width: '85%',
    backgroundColor: '#263844',
    borderRadius: 25,
    height: 54,
    alignItems: 'center',
    justifyContent: 'center',
    marginTop: 15,
    marginBottom: 15,
  },
  buttonText: {
    color: 'white',
    fontSize: 20,
  },
  logo: {
    fontWeight: 'bold',
    fontSize: 54,
    color: '#263844',
    marginBottom: 20,
  },
  Info: {
    fontWeight: 'bold',
    fontSize: 22,
    color: '#263844',
    marginBottom: 20,
  },
});

export default Profile;

Answer 1

Its all getting render before the results have been returned, you need include useEffect and run your firebase from within inside the useEffect function.

This is pretty decent blog and will help with the understanding of hooks.

Something like this (untested);

 import 'react-native-gesture-handler';
import auth, {firebase} from '@react-native-firebase/auth';
import firestore from '@react-native-firebase/firestore';
//import * as React from 'react';
import React, {useEffect, useState} from 'react';

import {NavigationContainer} from '@react-navigation/native';
import {
  StyleSheet,
  Picker,
  SafeAreaView,
  Text,
  View,
  TextInput,
  TouchableOpacity,
  Button,
} from 'react-native';
import {createStackNavigator} from '@react-navigation/stack';
import {ScrollView} from 'react-native-gesture-handler';

const Profile = ({navigation}) => {
  const [firstName, setFname] = useState('');
  
 // const db = firebase.firestore();
 // const { email } = firebase.auth().currentUser;
const email = ‘Sprint3@test.com’;

useEffect( () => {
  db.collection('users')
    .where('email', '==', usersEmail)
    .get()
    .then(function (querySnapshot) {
      // This will step over every doc that has that email, you should limit it one and organise by an updated field. .limit(1)
      querySnapshot.forEach(function (doc) {
        const fn = doc.get('firstName');
        setFname(fn);
        
       // Add whatever states from the data you need or just one object with all the info in.
      });
    })
    .catch(function (error) {
      console.log('Error getting documents: ', error);
    });
}, []);
    
    

  return (
    
    <SafeAreaView style={styles.container2}>
      <ScrollView>
        <View style={styles.container}>
          <Text style={styles.logo}>Profile</Text>
          <Text style={styles.Info}>
            Name: {firstName} 
          </Text>
          <TouchableOpacity
            style={styles.button}
            onPress={() => navigation.navigate('EditProfile')}>
            <Text style={styles.buttonText}>Edit Profile</Text>
          </TouchableOpacity>

          <TouchableOpacity
            style={styles.button}
            onPress={() => navigation.navigate('Messages')}>
            <Text style={styles.buttonText}>My Messages</Text>
          </TouchableOpacity>
        </View>
      </ScrollView>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#2c9f45',
    alignItems: 'center',
    justifyContent: 'center',
  },
  container2: {
    flex: 1,
    backgroundColor: '#2c9f45',
    justifyContent: 'center',
  },
  button: {
    width: '85%',
    backgroundColor: '#263844',
    borderRadius: 25,
    height: 54,
    alignItems: 'center',
    justifyContent: 'center',
    marginTop: 15,
    marginBottom: 15,
  },
  buttonText: {
    color: 'white',
    fontSize: 20,
  },
  logo: {
    fontWeight: 'bold',
    fontSize: 54,
    color: '#263844',
    marginBottom: 20,
  },
  Info: {
    fontWeight: 'bold',
    fontSize: 22,
    color: '#263844',
    marginBottom: 20,
  },
});

export default Profile;