FAQ: Navigation - Authentication Flow

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This community-built FAQ covers the “Authentication Flow” exercise from the lesson “Navigation”.

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This exercise can be found in the following Codecademy content:

Learn React Native

FAQs on the exercise Authentication Flow

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[orangetrumpet]

Hey - could use help on this. My component actually works, and displays the right screen based on hasUser, but Step 3 won’t give me the check. Here’s my component.

import React, { createContext, useContext, useState } from "react";
import { StyleSheet, Text, View, Button } from "react-native";
import { NavigationContainer } from "@react-navigation/native";
import { createStackNavigator } from "@react-navigation/stack";

// Our global authentication state, with default values
export const AuthContext = createContext({
  hasUser: false,
  setUser: () => {},
});

const LoginScreen = () => {
  const { setUser } = useContext(AuthContext);

  return (
    <View style={styles.layout}>
      <Text style={styles.title}>Login</Text>
      <Button title="Log In" onPress={() => setUser(true)} />
    </View>
  );
};

const FeedScreen = () => {
  const { setUser } = useContext(AuthContext);

  return (
    <View style={styles.layout}>
      <Text style={styles.title}>Feed</Text>
      <Button title="Log Out" onPress={() => setUser(false)} />
    </View>
  );
};

const Stack = createStackNavigator();

export const AppNavigator = () => {
  const { hasUser } = useContext(AuthContext);

  return (
    <Stack.Navigator>
      {hasUser
      ? <Stack.Screen name="Feed" component={FeedScreen} />
      : <Stack.Screen name="Log In" component={LoginScreen} />
      }
    </Stack.Navigator>
  );
};

const App = () => {
  // This is linked to our global authentication state.
  // We connect this in React to re-render components when changing this value.
  const [hasUser, setUser] = useState(false);

  return (
    <AuthContext.Provider value={{ hasUser, setUser }}>
      <NavigationContainer>
        <AppNavigator />
      </NavigationContainer>
    </AuthContext.Provider>
  );
};

export default App;

const styles = StyleSheet.create({
  layout: {
    flex: 1,
    justifyContent: "center",
    alignItems: "center",
  },
  title: {
    fontSize: 32,
    marginBottom: 16,
  },
});

[giga8354099305]

While doing this exercise I wondered, why does the setUser function even work? I read up on context in the React docs but I can’t seem to find my answer. I mean, setUser is literally just an empty function that shouldn’t do anything, and yet when we pass in a Boolean value it somehow affects the hasUser property. This is extremely confusing to me, thanks for any explanation.