As I know about it, This checks and gives warnings for React-Native code and its lifecycles.
I read about it from What is StrictMode in react?
How can I use it in react native ?
Here is a simple example to use StrictMode in React Native
StrictMode can be directly imported from React and can used like wrapping up View inside it.
import React, {Component, StrictMode} from 'react';
import {View} from 'react-native';
class Example extends Component {
render() {
return (
<StrictMode>
<View />
</StrictMode>
);
}
}
export default Example;
Related
I'm creating a library of React Native components.
On my library I have this simple component
import React from 'react'
import {View, Text } from 'react-native'
export default function App() {
return <View>
<Text>Hello</Text>
</View>
}
Then, on the app I'm using this component
import React from 'react'
import { View } from 'react-native'
import App from '#components-lib/App'
export default function RootApp() {
return (
<View>
<App />
</View>
)
}
So far everything works. Now, I need to make my simple component observable (I'm using mobx), but then if I change my simple component to
import React from 'react'
import {View, Text } from 'react-native'
import { observer } from 'mobx-react-lite' <-- adding this line
export default function App() {
return <View>
<Text>Hello</Text>
</View>
}
By simply adding the import of observer I start to get tons of this error
Invariant Violation: No callback found with cbID 3902 and callID 1951
for module . Args:
'["{"codeFrame":{"content":"\u001b[0m \u001b[90m 20
|\u001b[39m }\u001b[0m\n\u001b[0m \u001b[90m 21
|...(truncated)..."]'
Any idea what the problem is? If I remove the observer import everything starts to work again...
I have a react-native app where I have developed a scanner feature using react-native-qrcode-scanner.However, when I try to scan the data, I get the below error-
error: can't find variable navigation
I see this error in onSuccess method at line authorizationToken.
My code-
import React, { Component } from 'react';
import {
Text,
View,
Image,
TouchableOpacity,
Linking
} from 'react-native';
import styles from '../assets/style';
import QRCodeScanner from 'react-native-qrcode-scanner';
export default class ScanScreen extends Component {
onSuccess(scanEvent) {
this.props.navigation.navigate("Result", {
'accessKey': scanEvent.data,
'authorizationToken':navigation.getParam('authorizationToken', undefined),
"userData": navigation.getParam('userData', undefined),
"methodName": "fetchData"
});
}
render() {
return (
<View style={styles.container}>
<QRCodeScanner
onRead={this.onSuccess.bind(this)}
/>
</View>
);
}
}
Any idea what I m missing here. Any help is much appreciated.Thanks in advance.
Make sure that Your Screen is registered in react-navigation config (follow this guide: can't find variable navigation).
Or pass navigation prop to it with HOC withNavigation: https://reactnavigation.org/docs/en/with-navigation.html. Instead export default class ScanScreen extends Component do class ScanScreen extends Component and at end of file do
export default withNavigation(ScanScreen);
Don't forget about importing Higher Order Component: import { withNavigation } from 'react-navigation';
Also be sure that all native parts are properly linked. For example react-native-gesture-handle (https://kmagiera.github.io/react-native-gesture-handler/docs/getting-started.html#linking).
navigation has to be part of props so accessing navigation using this.props.navigation solves this issue.
I'm bizarrely getting an error that a local file import can't be resolved by React Native.
Unable to resolve module `./components/MyComponent" from ".//App.js`: could not resolve `/Users/myusername/Desktop/mylibrary/components/MyComponent' as a file nor as a folder","name":"UnableToResolveError","type":"UnableToResolveError","errors":[{}]},"type":"bundling_error"}"
mylibrary/App.js:
import React from 'react';
import {
View,
Text,
StyleSheet,
ScrollView,
AsyncStorage,
} from 'react-native';
import MyComponent from './components/MyComponent';
mylibrary/components/MyComponent.jsx:
import React from 'react';
import { StyleSheet, Text, View } from 'react-native';
export default class MyComponent extends React.Component {
render() {
<View>
{this.props.children}
</View>
}
}
I tried renaming the file to be lowercase (mycomponent.jsx), and it didn't make a difference. I also tried restarting my simulator and resetting the cache, and it also didn't help.
The import statement by default try to import .js files, try renaming MyComponent.jsx to MyComponent.js.
Quoting the MDN:
The module to import from. This is often a relative or absolute path name to the .js file containing the module, excluding the .js extension. Certain bundlers may permit or require the use of the extension; check your environment. Only single quotes and double quotes Strings are allowed.
The component is wrong. You are not returning anything in the render method. Try this:
render() {
return(
<View>
{this.props.children}
</View>
)
}
I am trying to create a counter with react-native and redux, but i'm getting the error Expected a component class, got [object Object].
This is my index.android.js
import React, { Component } from 'react';
import { AppRegistry } from 'react-native';
import Root from './src/containers/Root';
import configureStore from './configureStore';
export default class CounterReactNativeRedux extends Component {
render() {
return (<Root store={configureStore()} />)
}
}
AppRegistry.registerComponent('CounterReactNativeRedux', () => CounterReactNativeRedux);
My code can be found here.
Found answers about this saying that it might be because of the class name not being capitalize but this is not the case.
Anyone any idea?
Look inside of your Counter.js. You have used div tags there which do not exist in React Native.
So import View tag from React Native and use that.
import {View} from 'react-native'
const Counter = ({ value }) => (
<View>{value}</View>
);
import React, { Component } from 'react';
import {
AppRegistry,
StyleSheet,
Text,
View
} from 'react-native';
import Login from './js/components/Login';
import userReducers from './js/reducers/user';
import { createStore, combineReducers } from 'redux';
import { Provider } from 'react-redux';
let store = createStore(combineReducers({userReducers}));
class App extends Component {
render() {
return (
<Login />
);
}
}
export default class Testextends Component {
render() {
return (
<Provider store = {store}>
<App />
</Provider>
// <View>
// <Text>jhdgf</Text>
// </View>
);
}
}
AppRegistry.registerComponent('Test', () => Test);
It gives me following error:
I'm trying one basic example of react-native with redux. If I remove TouchableHighlight also , the error still persists. Any ideas what is wrong here?
Its doesn't seems you're doing something wrong, on the code pasted, are you sure the error came from this part of your code ?
Maybe try to put between () your TouchableHighlight component, but I don't think that's going to change something...
Or try a ternary rather than a binary operation.
Also be sure that you import TouchableHighlight and Text from react-native.
Try to delete all not necessary white space
<View>{ !this.props.user.loggedIn &&
<TouchableHighlight onPress={this.onLoginButtonPress}>
<Text>Login</Text>
</TouchableHighlight>
}</View>
Because in the following example
<View> {...}</View>
you have two children: first white space and second all in curved brackets.
Had the same issue with the following React Native code:
import {Link} from 'react-router-native'
<Link to={props.url}>{props.title}</Link>
Spend few hours trying to understand why the similar code works in WEB but not in native view. There is no viable error messaging or hints from the React Native runtime on which component causes this failure, so it's insanely hard to identify the issue.
Managed to fix this crash by doing the following:
import {Link} from 'react-router-native'
import {Text} from "react-native";
<Link to={props.url}><Text>{props.title}</Text></Link>
Looks like the title text was treated as multiple elements, so we ended up with such an error.
This is not a solution for the subject. But, because there are so many ways to fail with this error in React Native, it may be useful to put this another example of such a crash for those who Googled and ended here.
First off, "export default class Testextends Component" should actually be "export default class Test extends Component"
the reason why that error is thrown is because the Provider component takes only one element.
for Example:
wrong:
<provider store = {store}>
<div/>
<div/>
<provider>
correct:
<provider store = {store}>
<App/>
<provider>
which you did correctly, if you commented the component. Try the class error and see if it works.