How to solve "Can't find variable: App" in React Native? - javascript

I am new to React Native and I don't understand how to solve this problem. I already installed react-native-gesture-handler.
I am getting this error in the command:
Accessing view manager configs directly off UIManager via UIManager['getConstants'] is no longer supported. Use UIManager.getViewManagerConfig('getConstants') instead.
This is a part of the code:
import { createAppContainer, DrawerNavigator } from 'react-navigation';
import { createStackNavigator } from 'react-navigation-stack';
import Home from "./src/screens/Home.js";
import first from "./src/screens/first.js";
import React from 'react';
class App extends React.Component{
render(){
return(
<RootStack/>
)
}
}
const RootStack = createStackNavigator ({
Home:{screen:Home,
navigationOptions: {
header: null
}},
first:{screen:first,
navigationOptions: {
header: null
}}
});
//const App = createAppContainer(RootStack);
export default App;

I think this way is better:
const AppNavigator = createSwitchNavigator({
Auth: {
screen: Auth
},
Root: {
screen: BottomTabNavigator
}
})
const AppContainer = createAppContainer(AppNavigator)
const App = () => {
return (
<AppContainer />
)
}
export default App
OR
if it didn't work then you better check your index.js file whether you imported App Component (Root component) correctly or not?

Related

how to pass 'web socket (Socket.Io) to certain screens (not a chat app)

i am having trouble passing Socket.Io socket to certain screens in my react native app, I want to share the socket with the navigation (like a prop I think I am not sure). Does someone have any suggestions on how to do it? I tried to use this approach(https://dev.to/bravemaster619/how-to-use-socket-io-client-correctly-in-react-app-o65) on react native and it didn't work.
I am open to ideas and my main goal is to share the same socket with two pages after the signin/signup and to send a token to confirm the user when the socket is making the connection.
app.js-
import React from 'react';
import { createAppContainer, createSwitchNavigator } from 'react-navigation';
import { createStackNavigator } from 'react-navigation-stack';
import { createBottomTabNavigator } from 'react-navigation-tabs';
import { setNavigator } from './src/navigationRef';
import AccountScreen from './src/screens/AccountScreen';
import SigninScreen from './src/screens/SigninScreen';
import SignupScreen from './src/screens/SignupScreen';
import ProductDetailScreen from './src/screens/ProductDetailScreen';
import ProductListScreen from './src/screens/ProductListScreen';
import AddProductScreen from './src/screens/AddProductScreen';
import ResolveAuthScreen from './src/screens/ResolveAuthScreen';
import { Provider as AuthProvider } from './src/context/AuthContext';
import { Provider as ProductProvider } from './src/context/ProductDetailContext';
import { SocketContext, socket} from './src/context/SocketContext';
import { FontAwesome } from '#expo/vector-icons';
const PlnatListFlow = createStackNavigator({
ProductList:ProductListScreen,
ProductDetail: ProductDetailScreen,
});
PlnatListFlow.navigationOptions = {
title: 'ProductList',
tabBatIcone: <FontAwesome name="th-list" size={20} />,
};
const switchNavigator = createSwitchNavigator({
ResolveAuth: ResolveAuthScreen,
loginFlow: createStackNavigator({
Signup: SignupScreen,
Signin: SigninScreen,
}),
mainFlow: createBottomTabNavigator({
PlnatListFlow: PlnatListFlow,
AddProduct: AddProductScreen,
Account: AccountScreen,
}),
});
const App = createAppContainer(switchNavigator);
export default () => {
return (
<SocketContext.Provider value={socket}>
<ProductProvider>
<AuthProvider>
<App
ref={(navigator) => {
setNavigator(navigator);
}}
/>
</AuthProvider>
</ProductProvider>
</SocketContext.Provider>
);
};
SocketContext.js-
import React from 'react';
import io from "socket.io-client";
import {url} from '../api/Config';
export const socket = io(url, {
transports: ["websocket"],
// upgrade:false,
});
export const SocketContext = React.createContext();

undefined is not an object '_this3.props.navigation()' error in react native

running my react app gives error in navigationOptions() but it is working fine in render() function
App.js
import React, { Component } from 'react';
import { AppRegistry, View } from 'react-native';
import AppNavigator from './routs.js'
class App extends Component {
render() {
return (
<AppNavigator />
)
}
}
export default App
routs.js
import React from 'react'
import Home from './home.js'
import Phone from './phone.js'
import PhoneScreen from './phoneScreen.js'
import {createStackNavigator, createAppContainer} from 'react-navigation';
const MainNavigator = createStackNavigator({
home: {screen: Home},
add: {screen: Phone},
userScreen: {screen: PhoneScreen},
});
const AppNavigator = createAppContainer(MainNavigator);
export default AppNavigator;
home.js
import React from 'react'
import { TouchableOpacity, Text, View, TouchableHighlight, StyleSheet, Button } from 'react-native';
import { Actions } from 'react-native-router-flux';
import {AsyncStorage} from 'react-native';
class Home extends React.Component {
constructor(props) {
super(props);
}
static navigationOptions = {
headerTitle: 'Contacts',
headerRight: (
<Button
onPress={() => this.props.navigation.navigate('add')}
title="create new contact"
color="#000000"
size="20"
/>
),
};
}
export default Home;
"undefind is not an object(evaluating '_this3.props.navigation')"
please give solution
From the React Navigation Docs:
The binding of this in navigationOptions is not the HomeScreen
instance, so you can't call setState or any instance methods on it.
This is pretty important because it's extremely common to want the
buttons in your header to interact with the screen that the header
belongs to.
So, as you can see, this is not what you think it is in this case. Here's more from the docs detailing a working example:
class HomeScreen extends React.Component {
static navigationOptions = ({ navigation }) => {
return {
headerTitle: <LogoTitle />,
headerRight: (
<Button
onPress={navigation.getParam('increaseCount')}
title="+1"
color="#fff"
/>
),
};
};
componentDidMount() {
this.props.navigation.setParams({ increaseCount: this._increaseCount });
}
state = {
count: 0,
};
_increaseCount = () => {
this.setState({ count: this.state.count + 1 });
};
/* later in the render function we display the count */
}
As you can see, changing navigationOptions from an object into a function allows you to grab the navigation reference. From there you can successfully navigate.

Cannot read property 'navigate' of undefined - React Native Navigation

I am currently working on a app which works with react native and I tried to make a flow using react-navigation working on this tutorial but I am having trouble at the point of running my project, I've done a lot of research and i just cant get to the solution, first for all I am using react-native-cli: 2.0.1 and react-native: 0.48.3, this is my code:
App.js:
import React, { Component } from 'react';
import { Text, Button, View } from 'react-native';
import {
StackNavigator,
} from 'react-navigation';
class App extends Component {
static navigationOptions = {
title: 'Welcome',
};
render() {
console.log(this.props.navigation);
const { navigate } = this.props.navigation;
return (
<View>
<Text>Go to maps!</Text>
<Button
onPress={() => navigate('Map')}
title="MAP"
/>
</View>
);
}
}
export default App;
my Router.js
import {
StackNavigator,
} from 'react-navigation';
import MapMarker from './MapMarker';
import App from './App';
export const UserStack = StackNavigator({
ScreenMap:
{
screen: MapMarker,
navigationOptions:
{
title: "Map",
header:null
},
},
ScreenHome:
{
screen: App,
navigationOptions:
{
title: "Home",
headerLeft:null
},
},
});
As you can see this is a pretty basic App which i just cant make work, this is a screenshot of my error on the simulator:
I would really really appreciate if you guys could help me with this.
Thanks.
You should change the code onPress={() => navigate('Map')} to onPress={() => navigate('ScreenMap')} and ScreenHome should be the first screen then ScreenMap as you want to navigate from App to MapMarker. Or you can set initialRouteName: ScreenHome in the stacknavigator.
You create your StackNavigator, but where do you use it? You should have something like
import React, { Component } from 'react';
import {
AppRegistry,
View
} from 'react-native';
import {
StackNavigator,
} from 'react-navigation';
export default class MyApp extends Component {
render() {
return (
<View style={{flex:1}}>
<StackNavigator/>
</View>
);
}
}
AppRegistry.registerComponent('MyApp', () => MyApp);
Now that your StackNavigator is controlling what is shown, your App component will have navigation in its props. Note, you do not "pass" the navigation prop. This is handled for you.

React Native navigation - undefined is not an object

I'm new to React native and trying to follow tutorials to learn however can't get navigation between screens to work. I have previously got it working fine with one screen but when adding navigation I get errors.
Following this: https://facebook.github.io/react-native/releases/next/docs/navigation.html
Gives me code like this:
import React from 'react';
import {
StackNavigator,
} from 'react-navigation';
export default class HomeScreen extends React.Component {
static navigationOptions = {
title: 'Welcome',
};
render() {
const { navigate } = this.props.navigation;
return (
<Button
title="Go to Jane's profile"
onPress={() =>
navigate('Profile', { name: 'Jane' })
}
/>
);
}
}
class ProfileScreen extends React.Component {
static navigationOptions = {
title: 'Profile',
};
render() {
return (
<Button title="do nothing"/>
);
}
}
const App = StackNavigator({
Home: { screen: HomeScreen },
Profile: { screen: ProfileScreen },
});
Trying to run this (through the expo app) results in the error
undefined is not an object (evaluating 'this.props.navigation.navigate')
So am I doing navigation correctly and how do I fix this error?
You need to use AppRegistry.registerComponent in your App.
A nice way of doing this is to create a src directory and then create the 2 js files, HomeScreen and ProfileScreen there. Then create and App.js on the same level as your index.android.js or index.ios.js and include these 2 files and declare the StackNavigator as you did in your code, but instead of const App you need to have const NameOfYourApp, where NameOfYourApp is how you named your project when you ran create-react-native-app.(If it is App, just leave it like that)
Then you need to add this line at the end, AppRegistry.registerComponent('NameOfYourApp', () => NameOfYourApp);
import React from 'react';
import {
StackNavigator,
} from 'react-navigation';
import HomeScreen from './src/HomeScreen'
import ProfileScreen from './src/ProfileScreen'
const NameOfYourApp = StackNavigator({
Home: { screen: HomeScreen },
Profile: { screen: ProfileScreen },
});
AppRegistry.registerComponent('NameOfYourApp', () => NameOfYourApp)
The final step is to import your App.js file in your index.android.js or index.ios.js
import './App';

ExNavigation throws an error saying initialRoute is not defined

Hi I'm new to Expo but I've been having a hard time trying to run my code. I'm stuck at having the error: You must specify initialRoute or initialStack to initialize this StackNavigation even though I already set it up.
Here's my main.js
import Expo from 'expo'
import React from 'react'
import { createStore } from 'redux'
import { Provider } from 'react-redux'
import {
NavigationProvider,
StackNavigation,
} from '#expo/ex-navigation'
import RootReducer from './src/reducers'
import Router from './src/navigation/Router'
const store = createStore(RootReducer)
const App = () => (
<Provider store={store}>
<NavigationProvider router={Router}>
<StackNavigation intitialRoute={Router.getRoute('splash')} />
</NavigationProvider>
</Provider>
)
Expo.registerRootComponent(App)
Here's my Router.js
import { createRouter } from '#expo/ex-navigation'
// Screens
import SplashScreen from '../screens/SplashScreen'
import LoginScreen from '../screens/LoginScreen'
const Router = createRouter(() => ({
splash: () => SplashScreen,
login: () => LoginScreen,
}))
export default Router
What seems to be the problem at my setup? I just followed the example on ExNavigation.
Here's my example on Sketch but can't make it run but will leave the link for the full code.
You have a typo in the prop's name in this part of the code
<StackNavigation intitialRoute={Router.getRoute('splash')} />
It is initialRoute instead of intitialRoute.

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