React Native render and switch with navigator onPress - react-native

I've just started to develop with React Native a week ago.
Can anyone help me with simple render and switch onPress to another view?
I've read tones of examples, but most of them are cutted or not well documents as if on FaceBook Doc pages. There was no totally completed example with Nav.
Here is what was done yet - View that should be rendered 1st:
import React, { Component } from 'react';
import {
AppRegistry,
StyleSheet,
Text,
View,
Image,
TextInput,
TouchableHighlight,
TouchableNativeFeedback,
Platform,
Navigator
} from 'react-native';
export default class SignUp extends Component {
buttonClicked() {
console.log('Hi');
this.props.navigator.push({title: 'SignUp', component:SignUp});
}
render() {
var TouchableElement = TouchableHighlight;
if (Platform.OS === ANDROID_PLATFORM) {
TouchableElement = TouchableNativeFeedback;
}
return (
<View style={styles.container}>
<Text style={styles.welcome}>
Welcome to Cross-Profi!
</Text>
<Text style={styles.field_row}>
<TextInput style={styles.stdfield} placeholder="Profession" />
</Text>
<Text style={styles.field_row}>
<TextInput style={styles.stdfield} placeholder="E-mail" />
</Text>
<Text style={styles.field_row}>
<TextInput style={styles.stdfield} secureTextEntry={true} placeholder="Password" />
</Text>
<TouchableElement style={styles.button} onPress={this.buttonClicked.bind(this)}>
<View>
<Text style={styles.buttonText}>Register</Text>
</View>
</TouchableElement>
{/* <Image source={require("./img/super_car.png")} style={{width:120,height:100}} />*/}
<Text style={styles.instructions}>
Press Cmd+R to reload,{'\n'}
Cmd+D or shake for dev menu
</Text>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
justifyContent: 'center',
alignItems: 'center',
backgroundColor: 'lightblue',
},
welcome: {
fontSize: 20,
textAlign: 'center',
margin: 10,
color: 'darkred',
},
instructions: {
textAlign: 'center',
color: '#333333',
marginBottom: 5,
},
field_row: {
textAlign: 'center',
color: '#999999',
margin: 3,
},
stdfield: {
backgroundColor: 'darkgray',
height: 50,
width: 220,
textAlign: 'center'
},
button: {
borderColor:'blue',
borderWidth: 2,
margin: 5
},
buttonText: {
fontSize: 18,
fontWeight: 'bold'
}
});
const ANDROID_PLATFORM = 'android';
Navigator class that should render different views:
import React, { Component } from 'react';
import {
AppRegistry,
StyleSheet,
Text,
View,
Platform,
Navigator
} from 'react-native';
var MainActivity = require('./app/MainActivity.js');
var SignUp = require('./app/SignUp.js');
class AwesomeProject extends Component {
/*constructor(props) {
super(props);
this.state = {text: ''};
}*/
render() {
// this.props.navigator.push({title:'SignUp'});
return (
<Navigator initialRoute={{title:'SignUp', component:SignUp}}
configureScene={() => {
return Navigator.SceneConfigs.FloatFromRight;
}}
renderScene={(route, navigator) =>
{
console.log(route, navigator);
if (route.component) {
return React.createElement(route.component, {navigator});
}
}
} />
);
}
}
const ANDROID_PLATFORM = 'android';
const routes = [
{title: 'MainActivity', component: MainActivity},
{title: 'SignUp', component: SignUp},
];
AppRegistry.registerComponent('AwesomeProject', () => AwesomeProject);
It doesn't seem to be clear whether there must be require of a class and declaration of class as export default.
There is an error: Element type is invalid: expected a string, ... but got object etc
Help with examples would be great. Thx

In your require call, you should either replace it import statement or use default property of require module i.e:
var MainActivity = require('./app/MainActivity.js').default;
or use
import MainActivity from "./app/MainActivity";
In ES6, require doesn't assign default property of module to variable.
See this blog post for better understanding of require working in es6

Related

Error: Element type is invalid: expected a string (for build-in components) or a class/function... - REACT NATIVE

I got this error while working on my Content.js file:
Before this everything was fine so I know it's not App.js or another file.
I've tried 'npm install' just in case... Most people online that experienced similar errors mention that it might have to do with the way the component is exported but I already changed it to 'export default class Content extends Component' just like most people suggested.
This is the file:
Content.js
import React, { Component } from "react";
import { StyleSheet, View, ActivityIndicator, ScrollView, Card, Text} from 'react-native';
import firebase from '../../firebase';
export default class Content extends Component {
constructor() {
super();
this.state = {
isLoading: true,
article: {},
key: ''
};
}
componentDidMount() {
const ref = firebase.firestore().collection('articles').doc('foo');
ref.get().then((doc) => {
if (doc.exists) {
this.setState({
article: doc.data(),
key: doc.id,
isLoading: false
});
} else {
console.log("No such document!");
}
});
}
render() {
if(this.state.isLoading){
return(
<View style={styles.activity}>
<ActivityIndicator size="large" color="#0000ff" />
</View>
)
}
return (
<ScrollView>
<Card style={styles.container}>
<View style={styles.subContainer}>
<View>
<Text h3>{this.state.article.title}</Text>
</View>
<View>
<Text h5>{this.state.article.content}</Text>
</View>
</View>
</Card>
</ScrollView>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
padding: 20
},
subContainer: {
flex: 1,
paddingBottom: 20,
borderBottomWidth: 2,
borderBottomColor: '#CCCCCC',
},
activity: {
position: 'absolute',
left: 0,
right: 0,
top: 0,
bottom: 0,
alignItems: 'center',
justifyContent: 'center'
},
})
You have imported Card from the react-native but React native does not provide Card component inbuilt.

React-Native Constructor

Please help me find what is wrong in the following React-Native code?
It says after constructor (props) should have ';' semicolon. I don't know if I declared it in the right way.
import React from 'react';
import { StyleSheet, TextInput, View } from 'react-native';
export default function App() {
constructor (props){
this.state = {
text: 'HI'
}
}
render () {
return (
<View style={styles.container}>
<TextInput style={styles.input}
placeholder = 'Enter Value...'
placeholderTextColor ='#E74292'
onChangeText = {(text) => {
this.setState({text})
}}
/>
</View>
);
}
const styles = StyleSheet.create({
container:{
flex:1,
backgroundColor:'#F4C724',
},
input :{
marginTop:30,
height:30,
width:30,
borderWidth:2,
padding:10,
borderRadius: 5,
borderColor:'#1287A5'
}
}
);
You should declare the component as class instead of function if you want a constructor:
import React from 'react';
import { StyleSheet, TextInput, View } from 'react-native';
export default class App {
constructor(props) {
this.state = {
text: 'HI'
};
}
render() {
return (
<View style={styles.container}>
<TextInput
style={styles.input}
placeholder="Enter Value..."
placeholderTextColor="#E74292"
onChangeText={text => {
this.setState({ text });
}}
/>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: '#F4C724'
},
input: {
marginTop: 30,
height: 30,
width: 30,
borderWidth: 2,
padding: 10,
borderRadius: 5,
borderColor: '#1287A5'
}
});
constructor only works in class based component so switch to class based component rather than . functional whihc is now.
import React from 'react';
import { StyleSheet, TextInput, View } from 'react-native';
export default class App extends React.Component{
constructor(props) {
this.state = {
text: 'HI'
};
}
render() {
return (
<View style={styles.container}>
<TextInput
style={styles.input}
placeholder="Enter Value..."
placeholderTextColor="#E74292"
onChangeText={text => {
this.setState({ text });
}}
/>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: '#F4C724'
},
input: {
marginTop: 30,
height: 30,
width: 30,
borderWidth: 2,
padding: 10,
borderRadius: 5,
borderColor: '#1287A5'
}
});
You need to study the difference between functional and class component.
Functional component is just a plain java-script function which also known as stateless component. They do not manage their own state or have access to the lifecycle methods.
for more please follow the link below:
https://medium.com/#Zwenza/functional-vs-class-components-in-react-231e3fbd7108
you can use useState , the dynamic function value loads to the initial variable on load
import React,{ useState } from 'react';
import { View, Text, Button, ImageBackground} from 'react-native';
export default function Home({navigation}){
//function getversion onload
const [initval,setInitval] = useState(()=>{ return '123456'});
return(
<View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
<Text> {initval} </Text>
</View>
);
}
You cannot have a constructor() in functional components. You should either change function component to class component or go and check out the react doc about React Hooks. You are going to have a better understanding of the differences between react class components and react functional components.

trying to expand or reduce view within a `Flatlist` when clicking on them based on their current state

I am trying to expand or reduce view within a Flatlist when clicking on them based on their current state. I am using data within mobx and connecting it to a react component. Even though console.log confirms that the state is changing after clicking on the view, it does not expand when clicked upon. It was working when the data was a react state, but I had to move it to mobx due to diverse interactions within the software. I think the action syntax and logic has to be changed or it might something else. Please can anyone help?
mobx code below:
import {observable, action} from 'mobx';
import {LayoutAnimation} from 'react-native'
class StateStorage {
#observable materials = [
{
name: 'RAG',
price: '$',
image: require("./Icons/RAG.jpg"),
expanded: false
},
{
name: 'GRAPE',
price: '$',
image: require("./Icons/GRAPE.jpg"),
expanded: false
},
{
name: 'FLAG',
price: '$',
image: require("./Icons/FLAG.jpg"),
expanded: false
},
#action changeLayout(index) {
LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut);
this.materials[index].expanded= !this.materials[index].expanded
console.log(this.materials[index].expanded)
}
#action chooseMaterial(index){
this.selectedMaterial = this.materials[index].name
console.log(this.selectedMaterial)
}
export default new StateStorage();
React-native code below:
import React, { Component } from 'react';
import { View, Text, FlatList, Image, ImageBackground, PixelRatio, Platform, UIManager, TouchableOpacity, LayoutAnimation }
from 'react-native';
import {widthPercentageToDP as wp, heightPercentageToDP as hp} from 'react-native-responsive-screen'
import DropDownItem from 'react-native-drop-down-item';
import StateStorage from './StateStorage';
import {observer} from 'mobx-react';
#observer
class App extends Component {
constructor (props) {
super(props)
this.state ={
}
if (Platform.OS === 'android') {
UIManager.setLayoutAnimationEnabledExperimental(true);
}
}
render() {
return (
<View
style={{
backgroundColor:'#262A2C',
flex:1
}}>
<FlatList
style={{marginTop:80,}}
data={StateStorage.materials}
renderItem={({ item, index }) => (
<View style={{}}>
<TouchableOpacity
onPress={() =>{
StateStorage.chooseMaterial(index)
}}>
<ImageBackground
source={item.image}
//pay FlatIcon or design personal one
style={{
resizeMode: 'contain',
position:'relative',
width: wp('100%'),
left: wp('0%'),
borderBottomWidth: 1,
borderBottomColor: 'grey',
padding: hp('6%'),
}}
>
</ImageBackground>
</TouchableOpacity
<TouchableOpacity activeOpacity={0.8}
onPress={() => {
StateStorage.changeLayout(index)
}}
style={{ padding: 10,
backgroundColor:'black',
left:wp('-10.9%'),
top:hp('0%'),
width: wp('120%'),
height:hp('5%')}}>
<Image
style={{
width:wp('9%'),
height:hp('4.5%'),
tintColor:'white',
left:250,
top:-10
//tintColor:'#81F018'
}}
source={StateStorage.materials[index].expanded ? require('./Icons/arrowDown.png') : require('./Icons/arrowUp.png') }/>
</TouchableOpacity>
<View style={{height: StateStorage.materials[index].expanded ? null : 0,
overflow: 'hidden',
backgroundColor:'black' }}>
<Text
style={{
fontSize: 17,
left:150,
top:-10,
color: 'turquoise',
padding: 10}}>
Specs
</Text>
</View>
</View>
)}
}
export default App
Before the state was moved to mobx, I was using this method to make it work:
changeLayout = ({index}) => {
LayoutAnimation.configureNext(LayoutAnimation.Presets.easeInEaseOut);
this.setState(({ materials }) => ({
materials: materials.map((s, idx) =>
idx === index ? {...s, expanded: !StateStorage.materials[index].expanded} : {...s, expanded: false})
}));
console.log(StateStorage.materials[index].expanded)
}
You are searching for accordion :
Please refer to the native base accordion component. This is what you need.
https://docs.nativebase.io/Components.html#accordion-def-headref

How do i navigate between screens in my shopping app?

'm new to react-native and mobile application. I'm trying to build a basic shopping app.i have the sports options such as cricket,football,tennis and whenever the cricket button is pressed, the cricket products must be displayed and i can follow it up for the other two products
i tried using stack navigator to navigate between screens but i seem to get a error . i tried using createstacknavigator but it doesnt come out right
1.App.js
import React, { Component } from 'react';
import { Text, View } from 'react-native';
import { StackNavigator } from 'react-navigation'
import FirstScreen from './src/FirstScreen'
import SecondScreen from './src/cricket'
const Navigation = StackNavigator({
First: {screen: FirstScreen},
Second: {screen: SecondScreen}
});
export default Navigation
AppRegistry.registerComponent('AwesomeProject', () => Navigation);
2.FirstScreen.js
import React, { Component } from 'react';
import { Alert, AppRegistry, Image, Platform, StyleSheet, Text,
TouchableHighlight, TouchableOpacity, TouchableNativeFeedback,
TouchableWithoutFeedback, View } from 'react-native';
import { StackNavigator } from 'react-navigation'
export default class FirstScreen extends Component {
//_onPressButton() {
// Alert.alert('You tapped the button!')
//}
//_onLongPressButton() {
//Alert.alert('You long-pressed the button!')
//}
static navigationOptions = {
title: 'First Screen',
};
render() {
return (
<View style={styles.container}>
<TouchableOpacity onPress={this._onPressButton}>
<View style={styles.button}>
<Text style={styles.buttonText}>Cricket</Text>
</View>
</TouchableOpacity>
<TouchableOpacity onPress={this._onPressButton}>
<View style={styles.button}>
<Text style={styles.buttonText}>Football</Text>
</View>
</TouchableOpacity>
<TouchableOpacity onPress={this._onPressButton}>
<View style={styles.button}>
<Text style={styles.buttonText}>Tennis</Text>
</View>
</TouchableOpacity>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
paddingTop: 60,
alignItems: 'center'
},
button: {
marginBottom: 30,
width: 260,
alignItems: 'center',
backgroundColor: '#2196F3'
},
buttonText: {
padding: 20,
color: 'white'
}
});
// skip this line if using Create React Native App
//AppRegistry.registerComponent('AwesomeProject', () => Touchables);
3.Cricket.js
import React, { Component } from 'react';
import {Alert, Button, ScrollView, StyleSheet, AppRegistry, Text, View
} from 'react-native';
const styles = StyleSheet.create({
rowContainer: {
flex: 1,
height: 75,
width: '100%',
flexDirection: 'row', // children will be on the same line
justifyContent: 'space-between',
alignItems: 'center',
margin: 10,
},
buttonContainer: {
flex: 1,
},
text: {
flex: 2, // Text takes twice more space as button container
color: 'red',
fontWeight: 'bold',
fontSize: 20,
},
});
class Greeting extends Component {
static navigationOptions = {
title: 'Second Screen',
};
_onPressButton() {
Alert.alert('Sorry you have no credit!')
}
render() {
return (
<View style={styles.rowContainer}>
<Text style={styles.text}>{this.props.name}</Text>
<View style={styles.buttonContainer}>
<Button
onPress={this._onPressButton}
title="BUY"
/>
</View>
</View>
);
}
}
export default class SecondScreen extends Component {
render() {
return (
<ScrollView>
<View style={{alignItems: 'flex-start', top: 0, flex: 2,
backgroundColor: 'black'}}>
<Greeting name='Shoe- 800' />
<Greeting name='Jersey - 350' />
<Greeting name='Stockings - 100' />
<Greeting name='Cones - 50' />
<Greeting name='Whistle - 80' />
<Greeting name='Helmet - 750' />
<Greeting name='Tennis Ball-6 pack - 800' />
<Greeting name='Nets - 1500' />
<Greeting name='Leg Pads - 1000' />
<Greeting name='Stumps - 800' />
<Greeting name='Gloves - 600' />
</View>
</ScrollView>
);
}
}
When the cricket button is pressed, the screen should navigate to the list of cricketproducts which is the (cricket.js)
As you are using react-navigation, you just need to use the navigation prop. You have commented the part where you handle the press. Just change that function to actually navigate to the screen you want:
_onPressButton=()=>{
this.props.navigation.navigate("Second")
}
If you are not using arrow functions, you need to bind the function to have access to the this of that screen. To do that you need to add inside your constructor:
constructor(props){
super(props)
this._onPressButton.bind(this)
}
after that you can call it by doing:
_onPressButton() {
this.props.navigation.navigate("Second")
}
As you are using a stackNavigator, you have different ways to navigate to the other screen of the same stack. You have different ways to navigate. For example:
this.props.navigation.push("Second")
This method pushes a new screen to the stack, no matter what screen it is
this.props.navigation.navigate("Second")
Navigates to a new screen in the stack, will push it in the stack only if the screen hasn't been focussed before
this.props.navigation.replace("Second")
This will navigate to a new screen without pushing it to the stack, "replacing" the screen you was watching with the new one.
EDIT.
For the error you stated in the comment, it's because there's not an app container. To do so, just do:
import { createStackNavigator, createAppContainer } from 'react-navigation'
Then do
const Navigation = createAppContainer(createStackNavigator({
First: {screen: FirstScreen},
Second: {screen: SecondScreen}
}));
Use the Move Screen command.
this.props.navigation.navigate("Second")

Change underlineColorAndroid on Focus for TextInput in react-native

Similar to Focus style for TextInput in react-native, I am trying to change the property underlineColorAndroid for the textInput.
I am using React-Native 0.28.0
OnFocus, the attribute doesn't change. How do I change the underline to a different color onFocus?
My sample code is below:
'use strict';
import React, { Component } from 'react';
import {
AppRegistry,
StyleSheet,
Text,
View,
TextInput,
ScrollView
} from 'react-native';
class RNPlayground extends Component {
constructor(props) {
super(props);
this.state = {
hasFocus: false
}
}
_onBlur() {
this.setState({hasFocus: false});
}
_onFocus() {
this.setState({hasFocus: true});
}
_getULColor(hasFocus) {
console.error(hasFocus);
return (hasFocus === true) ? 'pink' : 'violet';
}
render() {
console.error("this.state=");
console.error(this.state);
console.error("this.state.hasFocus=");
console.error(this.state.hasFocus);
return (
<View style={styles.container}>
<ScrollView>
<TextInput
placeholder="textInput"
onBlur={ () => this._onBlur() }
onFocus={ () => this._onFocus() }
style={styles.instructions}
underlineColorAndroid={this._getULColor(this.state.hasFocus)}/>
</ScrollView>
<TextInput>Some sample text</TextInput>
</View>
);
}
};
const styles = StyleSheet.create({
container: {
flex: 1,
justifyContent: 'center',
alignItems: 'center',
backgroundColor: '#F5FCFF',
},
welcome: {
fontSize: 28,
textAlign: 'center',
margin: 10,
},
instructions: {
textAlign: 'center',
color: '#333333',
fontSize: 19,
marginBottom: 5,
}
});
AppRegistry.registerComponent('RNPlayground', () => RNPlayground);
Well, your code is correct and it should work properly.
Here is working example
Please, stop downvote this answer. Unfortunately rnplay service isn’t available anymore, as like this example. Or downvote but explain your point.