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Is there a way to use mutable arrays in FlatList?

I'm trying to make a toy stopwatch app in order to learn react-native.
I made a lap system, but it is getting way too slow when there are >15 laps. I think the poor performance point is the laps: this.state.laps.concat([d - this.state.lapTimerStart]) part, because of .concat is making a new object every time the Lap button is pressed.
I've heard that .push is way faster than .concat.
So I tried to use .push, but because .push was mutating the array, and FlatList was a PureComponent so it re-rendered only when the props have changed.
I found a way, but it was just the same as doing .concat because basically, it was
let lapArr = this.state.laps;
Array.prototype.push.apply(lapArr, [d - this.state.lapTimerStart]);
this.setState({
laps: lapArr,
})
The full code is
import React, {Component} from 'react';
import {
View,
Text,
StyleSheet,
TouchableHighlight,
FlatList,
} from 'react-native';
import {useTheme} from 'react-native-paper';
import TimeFormatter from 'minutes-seconds-milliseconds';
class Stopwatch extends Component {
constructor(props) {
super(props);
this.state = {
laps: [],
isRunning: false,
mainTimer: null,
lapTimer: null,
mainTimerStart: null,
lapTimerStart: null,
};
}
handleLapReset() {
let {isRunning, mainTimerStart, lapTimer} = this.state;
if (mainTimerStart) {
if (isRunning) {
const d = new Date();
this.setState({
lapTimerStart: d,
lapTimer: d - this.state.lapTimerStart + lapTimer,
laps: this.state.laps.concat([d - this.state.lapTimerStart]),
});
return;
}
this.state.laps = [];
this.setState({
mainTimerStart: null,
lapTimerStart: null,
mainTimer: 0,
lapTimer: 0,
});
}
}
handleStartStop() {
let {isRunning, mainTimer, lapTimer} = this.state;
if (isRunning) {
clearInterval(this.interval);
this.setState({
isRunning: false,
});
return;
}
const d = new Date();
this.setState({
mainTimerStart: d,
lapTimerStart: d,
isRunning: true,
});
this.interval = setInterval(() => {
const t = new Date();
this.setState({
mainTimer: t - this.state.mainTimerStart + mainTimer,
lapTimer: t - this.state.lapTimerStart + lapTimer,
});
}, 10);
}
_renderTimers() {
const {theme} = this.props;
return (
<View
style={[
styles.timerWrapper,
{backgroundColor: theme.colors.background},
]}>
<View style={styles.timerWrapperInner}>
<Text style={[styles.lapTimer, {color: theme.colors.text}]}>
{TimeFormatter(this.state.lapTimer)}
</Text>
<Text style={[styles.mainTimer, {color: theme.colors.text}]}>
{TimeFormatter(this.state.mainTimer)}
</Text>
</View>
</View>
);
}
_renderButtons() {
const {theme} = this.props;
return (
<View style={styles.buttonWrapper}>
<TouchableHighlight
underlayColor={theme.colors.disabled}
onPress={this.handleLapReset.bind(this)}
style={[styles.button, {backgroundColor: theme.colors.background}]}>
<Text style={[styles.lapResetBtn, {color: theme.colors.text}]}>
{this.state.mainTimerStart && !this.state.isRunning
? 'Reset'
: 'Lap'}
</Text>
</TouchableHighlight>
<TouchableHighlight
underlayColor={theme.colors.disabled}
onPress={this.handleStartStop.bind(this)}
style={[styles.button, {backgroundColor: theme.colors.background}]}>
<Text
style={[styles.startBtn, this.state.isRunning && styles.stopBtn]}>
{this.state.isRunning ? 'Stop' : 'Start'}
</Text>
</TouchableHighlight>
</View>
);
}
_renderLaps() {
return (
<View style={styles.lapsWrapper}>
<FlatList
data={this.state.laps}
renderItem={this.renderItem}
keyExtractor={this.keyExtractor}
/>
</View>
);
}
keyExtractor(item, index) {
return index.toString();
}
renderItem({item, index}) {
return (
<View style={styles.lapRow}>
<View style={styles.lapStyle}>
<View style={styles.lapBoxStyle} />
<Text style={styles.lapNumber}>{index + 1}</Text>
</View>
<View style={styles.lapStyle}>
<Text style={styles.lapTime}>{TimeFormatter(item)}</Text>
</View>
</View>
);
}
render() {
return (
<View style={styles.container}>
<View style={styles.top}>{this._renderTimers()}</View>
<View style={styles.middle}>{this._renderButtons()}</View>
<View style={styles.bottom}>{this._renderLaps()}</View>
</View>
);
}
}
const styles = StyleSheet.create({
container: {flex: 1},
timerWrapper: {
justifyContent: 'center',
flex: 1,
},
top: {
flex: 1,
},
middle: {
flex: 1,
backgroundColor: '#F0EFF5',
},
bottom: {
flex: 2,
},
mainTimer: {
fontSize: 50,
fontFamily: 'CircularStd-Medium',
alignSelf: 'center',
},
lapTimer: {
fontSize: 18,
fontFamily: 'CircularStd-Medium',
alignSelf: 'flex-end',
},
timerWrapperInner: {
alignSelf: 'center',
},
buttonWrapper: {
flexDirection: 'row',
justifyContent: 'space-around',
paddingTop: 15,
paddingBottom: 30,
},
button: {
height: 80,
width: 80,
borderRadius: 40,
backgroundColor: '#FFF',
justifyContent: 'center',
alignItems: 'center',
},
lapRow: {
flexDirection: 'row',
justifyContent: 'space-between',
height: 40,
paddingTop: 10,
},
lapNumber: {
flexDirection: 'row',
fontSize: 16,
fontFamily: 'CircularStd-Book',
color: '#777',
flex: 1,
},
lapTime: {
flexDirection: 'row',
color: '#000',
fontSize: 20,
fontFamily: 'CircularStd-Book',
flex: 1,
},
startBtn: {
color: '#0C0',
fontFamily: 'CircularStd-Book',
},
stopBtn: {
color: '#C00',
fontFamily: 'CircularStd-Book',
},
lapsWrapper: {
backgroundColor: '#ddd',
},
lapResetBtn: {
fontFamily: 'CircularStd-Book',
},
lapStyle: {
width: '40%',
flexDirection: 'row',
},
lapBoxStyle: {
flexDirection: 'row',
flex: 1,
},
});
export default function StopwatchScreen(props) {
const theme = useTheme();
return <Stopwatch {...props} theme={theme} />;
}
I tried not to use arrow functions, many news, but it didn't help that much.

FlatList is a pure component and it is mandatory to give new ref of data prop to render list . You should use concat but it created new object.
i think the main issue is renderItem.
create a separate PureComponent to avoid re-rendeing of items
class Item extends PureComponent {
const {item,index} = this.props;
return (
<View style={styles.lapRow}>
<View style={styles.lapStyle}>
<View style={styles.lapBoxStyle} />
<Text style={styles.lapNumber}>{index + 1}</Text>
</View>
<View style={styles.lapStyle}>
<Text style={styles.lapTime}>{TimeFormatter(item)}</Text>
</View>
</View>
);
}
and use in render item
renderItem({item, index}) {
return (
<Item item={item} index={index} />
);
}

React Native Component Exception <Text strings must be rendered within a Text component>

I am trying to build a react native application with the expo, First I try to build this application with my chrome web browser, it was worked without any issue after that I try to test the application with my android device and I'm getting an exception - "Text strings must be rendered within a <Text> component" HomeScreen.js files. I have no idea why this happened. My code as follows,
/*This is an Example of Grid View in React Native*/
// import * as React from "react";
import React from 'react';
import { Image, FlatList, StyleSheet, View, Text, TouchableOpacity, TextInput } from 'react-native';
import { COLORS } from '../../asserts/Colors/Colors';
import { CATEGORIES } from '../../asserts/mocks/itemListData';
import CategoryGridTitle from '../components/HomeGridTile';
import { HeaderButtons, Item } from 'react-navigation-header-buttons';
import { HeaderButton } from '../components/HeaderButton';
import HomeScreenButton from '../components/HomeScreenButton';
//import all the components we will need
const renderTopBarItems = (topBarItems) => {
return (
<TouchableOpacity
style={styles.topBar}>
<Text style={styles.textStyle}> {topBarItems.item.category} </Text>
</TouchableOpacity>
)
}
const HomeScreen = props => {
const renderGridItem = (itemData) => {
return <CategoryGridTitle
title={itemData.item.title}
image={itemData.item.image}
onSelect={() => {
props.navigation.navigate({
routeName: 'PaymentHandlerScreen',
params: {
categoryId: itemData.item.id
}
});
}} />;
}
// const [images, setImages] = React.useState(picsumImages);
return (
<View style={styles.mainBody}>
<View style={styles.searchContainer}>
<TextInput
placeholder='Search'
style={styles.formField}
placeholderTextColor={'#888888'}
/>
<TouchableOpacity onPress={() => props.navigation.navigate('BarCodeScannerScreen')}
style={styles.saveFormField}>
<Image
source={require('../../../images/barcode.png')}
style={{
width: '100%',
height: '30%',
resizeMode: 'contain',
alignContent: 'center',
}}
/> </TouchableOpacity>
</View>
<View style={styles.tabBar}>
<FlatList
horizontal
pagingEnabled={true}
showsHorizontalScrollIndicator={false}
keyExtractor={(item, index) => item.id}
data={CATEGORIES}
renderItem={renderTopBarItems} />
</View>
<FlatList
keyExtractor={(item, index) => item.id}
data={CATEGORIES}
renderItem={renderGridItem}
numColumns={3} />
<HomeScreenButton style={styles.buttonView} />
</View>
);
};
HomeScreen.navigationOptions = navigationData => {
return {
headerTitle: 'Tickets',
headerRight: (
<HeaderButtons HeaderButtonComponent={HeaderButton}>
<Item
title='profile'
iconName='ios-star'
onPress={() => {
console.log('profile clicked');
}} />
<Item
title='more'
iconName='md-more'
onPress={() => {
console.log('more clicked');
}} />
</HeaderButtons>
)
};
};
export default HomeScreen;
const styles = StyleSheet.create({
mainBody: {
flex: 1,
justifyContent: 'center',
backgroundColor: COLORS.background,
paddingTop: '3%',
},
searchContainer: {
flex: 1,
flexDirection: 'row',
},
tabBar: {
paddingBottom: '3%',
},
topBar: {
width: 150,
borderWidth: 1,
borderRadius: 20,
borderColor: COLORS.primary_blue,
padding: '5%',
marginLeft: '5%',
},
textStyle: {
color: COLORS.primary_blue,
textAlign: 'center',
fontWeight: 'bold',
fontSize: 14,
},
formField: {
flex: 4,
borderWidth: 1,
padding: '4%',
marginLeft: '2%',
borderRadius: 10,
borderColor: COLORS.gray,
backgroundColor: COLORS.gray,
fontSize: 15,
height: '35%',
},
saveFormField: {
flex: 0.5,
justifyContent: 'space-between',
alignItems: 'center',
margin: 10,
},
buttonView: {
position: 'absolute',
bottom: 0,
left: 0,
},
});
Thank you.

I ran into this error a couple of times. RN doesn't like extra spaces in tags. try removing the spaces before and after {topBarItems.item.category}
<Text style={styles.textStyle}>{topBarItems.item.category}</Text>

React Native Flat List

I am trying to use the React Native FlatList to loop thru a fetch API response for a news page that will load from a modal that contains a web view element. Everything seems to work fine, but every time I click the news article, it always loop thru all of them and give me the last article instead of the clicked article. If I console.log(item.title) it returns the clicked article title, but does not load it. I even passed the article data as a state but I am not sure what I am doing wrong, please help. Please ignore the extra code since I am focus on making sure it works properly before refactoring and removing the unused CSS. Here is the code. Let me know if you need a repo to post the link. Thanks in advance.
import React, { Component } from "react";
import { WebView } from "react-native-webview";
import {
View,
StyleSheet,
Text,
ActivityIndicator,
Image,
Button,
Linking,
TouchableOpacity,
Modal
} from "react-native";
import { FlatList } from "react-native-gesture-handler";
export default class NewsPage extends Component {
constructor(props) {
super(props);
this.state = {
dataSource: [],
isLoading: true,
modalVisible: false
};
}
componentDidMount() {
return fetch(
"https://newsapi.org/v2/everything?q=empleos&language=es&apiKey=bc9471b0c90c4d1a8d41860292e59d6b"
)
.then(response => response.json())
.then(responseJson => {
this.setState(
{
isLoading: false,
dataSource: responseJson.articles
},
function() {}
);
})
.catch(error => {
console.error(error);
});
}
setModalVisible(articleData) {
this.setState({
modalVisible: true,
modalArticleData: articleData
});
}
closeModal = () => {
this.setState({
modalVisible: false,
modalArticleData: {}
});
};
render() {
if (this.state.isLoading) {
return (
<View style={{ flex: 1, padding: 20 }}>
<ActivityIndicator />
</View>
);
}
return (
<View style={{ flex: 1, paddingTop: 20 }}>
<FlatList
data={this.state.dataSource}
keyExtractor={({ id }, index) => id}
renderItem={({ item }) => (
<View style={styles.newsListContainer}>
<Image
style={styles.newsImage}
source={{
uri:
item.urlToImage != null
? item.urlToImage
: "../assets/icon.png"
}}
/>
<View style={styles.newsInfo}>
<Text numberOfLines={2} style={styles.newsTitle}>
{item.title}
</Text>
<Text numberOfLines={3} style={styles.newsDescription}>
{item.description}
</Text>
<Text>{item.author}</Text>
</View>
<View style={styles.newsLink}>
<Button
title="Leer"
onPress={() => {
console.log(item);
this.setModalVisible(item);
}}
// {Linking.openURL(item.url);}}
/>
</View>
<Modal
animationType="slide"
transparent={false}
visible={this.state.modalVisible}
>
<View style={styles.newsHeader}>
<TouchableOpacity
onPress={() => {
this.closeModal();
}}
>
<Text style={styles.newsClose}>Cerrar</Text>
</TouchableOpacity>
<Text>{item.title}</Text>
</View>
<WebView
startInLoadingState={true}
source={{ uri: item.url }}
style={{ padding: 8 }}
/>
</Modal>
</View>
)}
/>
</View>
);
}
}
NewsPage.navigationOptions = {
headerTitle: "Noticias en Español"
};
const styles = StyleSheet.create({
mainBackgroundColor: {
backgroundColor: "#007bff",
padding: 8
},
mainBackground: {
alignItems: "center",
justifyContent: "center",
flex: 1
},
textHeader: {
backgroundColor: "#fff",
marginTop: 16,
fontSize: 32,
padding: 8,
borderRadius: 8,
color: "#007bff"
},
firstText: {
fontSize: 16,
marginTop: 16,
marginBottom: 0,
color: "#fff"
},
phone: {
marginTop: 16,
color: "#fff"
},
secondText: {
fontSize: 16,
marginTop: 0,
color: "#fff"
},
thirdText: {
fontSize: 16,
marginTop: 8,
color: "#ffffff",
textTransform: "uppercase",
textAlign: "center",
padding: 8,
marginBottom: 12
},
firstButton: {
marginBottom: 16
},
newsListContainer: {
width: "100%",
marginBottom: 4,
padding: 4,
flex: 1,
flexDirection: "row",
alignItems: "center",
justifyContent: "space-between"
},
newsImage: {
flexBasis: "25%",
height: "100%"
},
newsInfo: {
flexBasis: "55%",
padding: 2,
alignSelf: "flex-start"
},
newsLink: {
flexBasis: "20%"
},
newsTitle: {
fontSize: 20,
color: "#000000",
marginLeft: 8
},
newsDescription: {
fontSize: 12,
color: "efefef",
marginLeft: 8
},
newsHeader: {
flexDirection: "row",
alignItems: "center",
justifyContent: "space-between",
padding: 4
},
newsClose: {
fontSize: 20,
color: "red"
}
});

In your Modal, you are using
<Text>{item.title}</Text>
instead of
<Text>{this.state.modalArticleData.title}</Text>
also for the WebView component do the same.
source={{ uri: this.state.modalArticleData.url }}
One More Thing:
import Flatlist from react-native instead of
react-native-gesture-handler

React native - remove object from array

I have a Modal that displays a list of contacts. onPress, contacts are dynamically added to a View.
If a contact has already been added, on second onPress I would like to remove it from the View. For that I'm amending the state/array containing the contacts, using splice but it removes all the contacts at once.
I'm also trying to update the state of the 'Add' icon. If a contact has been added the Add icon Image should become the active one.
Not sure what I'm doing wrong?
Here's the Modal opened up:
My code:
import React, {Component} from 'react'
import {
Text,
View,
ListView,
ScrollView,
StyleSheet,
Image,
TouchableHighlight,
TextInput,
Modal,
} from 'react-native'
const friends = new ListView.DataSource({
rowHasChanged: (r1, r2) => r1 !== r2
}).cloneWithRows([
{
id: 1,
firstname: 'name1',
surname: 'surname1',
image: require('../images/friends/avatar-friend-01.png')
},
{
id: 2,
firstname: 'name2',
surname: 'surname2',
image: require('../images/friends/avatar-friend-02.png')
},
{
id: 3,
firstname: 'name3',
surname: 'surname3',
image: require('../images/friends/avatar-friend-03.png')
},
])
class AppView extends Component {
state = {
isModalVisible: false,
contactsPicked: [],
friendsState: {},
}
setModalVisible = visible => {
this.setState({isModalVisible: visible})
}
pickContact = (friend) => {
if(this.state.contactsPicked.indexOf(friend) < 0){
var tempFriendsState = this.state.friendsState
tempFriendsState[friend.id] = true
this.setState({
contactsPicked: [ ...this.state.contactsPicked, friend],
friendsState: tempFriendsState,
})
}
else{
let index = this.state.contactsPicked.indexOf(friend)
let nextContacts = this.state.contactsPicked
nextContacts.splice(index,1)
let tempFriendsState = this.state.friendsState
tempFriendsState[friend.id] = false
this.setState({
contactsPicked: nextContacts,
friendsState: tempFriendsState,
})
}
}
removeContact = (friend) => {
let index = this.state.contactsPicked.indexOf(friend)
let nextContacts = this.state.contactsPicked
nextContacts.splice(index,1)
this.setState({
contactsPicked: nextContacts,
})
}
_renderAddFriendTile = () => {
return(
<View style={[styles.step, styles.stepThree]}>
<View style={{flex:1}}>
<Text style={styles.heading}>Friend tile</Text>
</View>
{this.state.contactsPicked.length > 0 && (
<TouchableHighlight onPress={() => {this.removeContact(this.state.contactsPicked)}}>
<View>
{this.state.contactsPicked.map((contact,index) => (
<View key={index} style={[styles.row, styles.friendRow]}>
<Image source={contact.image} style={styles.friendIcon}></Image>
<Text style={styles.name}>{contact.firstname} </Text>
<Text style={styles.name}>{contact.surname}</Text>
<View style={styles.roundIconContainer}>
<View style={styles.roundIcon}>
<View style={[styles.removeButton, styles.buttonSmall]}>
<Image source={require('../images/button-cross-small.png')} style={styles.crossIconSmall}></Image>
</View>
</View>
</View>
</View>
))}
</View>
</TouchableHighlight>
)}
<TouchableHighlight style={styles.addFriendButtonContainer} onPress={() => {this.setModalVisible(true)}}>
<View style={styles.addFriendButton}>
<Text style={styles.addFriendButtonText}>Add friends</Text>
</View>
</TouchableHighlight>
</View>
)
}
render(){
return (
<ScrollView style={styles.container}>
<Modal
animationType={'fade'}
transparent={true}
visible={this.state.isModalVisible}
>
<View style={styles.addFriendModalContainer}>
<View style={styles.addFriendModal}>
<TouchableHighlight onPress={() => {this.setModalVisible(false)}}>
<View>
<Text>Close</Text>
</View>
</TouchableHighlight>
<ListView
dataSource={friends}
renderRow={(friend) => {
return (
<FriendRow
friend={friend}
pickContact={this.pickContact}
isSelected={this.state.friendsState[friend.id]}
/>
)
}}
/>
</View>
</View>
</Modal>
{this._renderAddFriendTile()}
</ScrollView>
)
}
}
class FriendRow extends Component {
render(){
return(
<TouchableHighlight onPress={() => {this.props.pickContact(this.props.friend)}}>
<View style={[styles.row, styles.friendRow]}>
<Image source={this.props.friend.image} style={styles.friendIcon}></Image>
<Text style={styles.name}>{this.props.friend.firstname} </Text>
<Text style={styles.name}>{this.props.friend.surname}</Text>
<View style={styles.roundIconContainer}>
<View style={styles.roundIcon}>
<View style={this.props.isSelected ? [styles.buttonActive, styles.buttonSmall]: [styles.modalButtonInactive, styles.buttonSmall]}>
<Image source={this.props.isSelected && require('../images/button-tick-small-on.png')} style={styles.buttonTickSmall}></Image>
</View>
</View>
</View>
</View>
</TouchableHighlight>
)
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: '#e1e1e1'
},
row: {
flexDirection: 'row',
alignItems: 'center',
justifyContent: 'center',
},
step: {
backgroundColor: '#ffffff',
borderRadius: 4,
borderLeftWidth: 5,
flex: 1,
marginLeft: 10,
marginRight: 10,
marginBottom: 10,
paddingLeft: 15,
paddingRight: 10,
paddingTop: 15,
paddingBottom: 20,
shadowOffset: {
width: 0,
height: 2,
},
shadowRadius: 2,
shadowOpacity: 0.2,
shadowColor: '#000000',
},
stepThree: {
borderLeftColor: '#ffbd18',
},
heading: {
textAlign: 'center',
fontWeight: 'bold',
fontSize: 15,
color: '#333333',
},
addFriendButtonContainer: {
marginTop:15,
flex:1,
alignItems: 'center',
justifyContent: 'center',
flexDirection: 'row',
},
addFriendButton: {
backgroundColor: '#ffbd18',
width: 270,
borderRadius: 4,
paddingTop: 15,
paddingBottom: 15,
},
addFriendButtonText: {
color: '#ffffff',
fontSize: 18,
fontWeight: 'bold',
textAlign: 'center',
},
pickContainer: {
flex:1,
flexDirection: 'row',
justifyContent: 'space-between',
alignItems: 'center',
borderRightWidth: 1,
},
pickWrapper: {
flex: 1,
flexDirection: 'row',
justifyContent: 'space-around',
alignItems: 'center',
marginTop: 10,
},
buttonBig: {
height: 60,
width: 60,
borderRadius: 30,
},
buttonSmall: {
height: 20,
width: 20,
borderRadius: 10,
},
buttonActive: {
backgroundColor: '#fd6769',
alignItems: 'center',
justifyContent: 'center',
},
buttonInactive: {
backgroundColor: '#eeeeee',
alignItems: 'center',
justifyContent: 'center',
},
removeButton:{
backgroundColor: '#cccbcb',
alignItems: 'center',
justifyContent: 'center',
},
modalButtonInactive: {
backgroundColor: '#ffffff',
borderWidth: 1,
borderColor: '#eeeeee',
},
buttonTickBig: {
width: 34,
height: 28,
},
buttonTickMinusBig: {
width: 18,
height: 8,
},
buttonTickSmall: {
width: 12,
height: 10,
},
crossIconSmall: {
width: 12,
height: 10,
},
pickText: {
color: '#c7c7c7',
fontWeight: 'bold',
},
addFriendModalContainer: {
flex: 1,
},
addFriendModal: {
flex: 1,
backgroundColor: '#ffffff',
borderRadius: 4,
paddingLeft: 15,
paddingRight: 10,
paddingTop: 20,
paddingBottom: 20,
shadowOffset: {
width: 0,
height: 2,
},
shadowRadius: 2,
shadowOpacity: 0.2,
shadowColor: '#000000',
textAlign: 'center',
},
nextButtonContainer: {
marginBottom: 20,
},
nextButton: {
textAlign:'right',
},
friendRow: {
height: 60,
borderBottomWidth: 1,
borderBottomColor: '#eeeeee',
justifyContent: 'flex-start',
},
friendIcon: {
width: 50,
height: 50,
marginRight: 25,
},
roundIconContainer:{
flex: 1,
flexDirection: 'row',
justifyContent: 'flex-end',
alignItems: 'flex-end',
},
roundIcon: {
height: 20,
width: 20,
borderRadius: 10,
backgroundColor: '#fd6769',
justifyContent: 'center',
alignItems: 'center',
marginRight: 20,
},
})
export default AppView

'using splice but it removes all the contacts at once.'
Because you're using splice method wrong. Check the parameters the method gets.
http://www.w3schools.com/jsref/jsref_splice.asp
[ ...this.state.contactsPicked, this.state.contactsPicked.splice(friend)]
this doesn't work as you expected as well. It merges two arrays.
var parts = ['shoulders', 'knees'];
var parts2 = ['shoulders'];
var lyrics = [ ...parts, ...parts2 ];
console.log(lyrics)
It seems you don't have to use spread operator([...arr,.arr2]),
you can simply do that
Since it re creates subs every time modal's visiblity changes and even if you change state of parent component's state it does not re render subs so you need to keep internal state for you sub components
Also your _renderAddFriendTile method was working wrong too. When
you take a look at it carefully you will realize your mistake.
Don't forget to change your icons with my test icons
class AppView extends Component {
constructor(props) {
super(props);
this.state = {
isModalVisible: false,
contactsPicked: [],
friendsState: {},
}
}
setModalVisible = visible => {
this.setState({isModalVisible: visible})
}
pickContact = (friend) => {
if(this.state.contactsPicked.indexOf(friend) < 0){
var tempFriendsState = this.state.friendsState
tempFriendsState[friend.id] = true
this.setState({
contactsPicked: [ ...this.state.contactsPicked, friend],
friendsState: tempFriendsState,
})
}
else{
let index = this.state.contactsPicked.indexOf(friend)
let nextContacts = this.state.contactsPicked
nextContacts.splice(index,1)
let tempFriendsState = this.state.friendsState
tempFriendsState[friend.id] = false
this.setState({
contactsPicked: nextContacts,
friendsState: tempFriendsState,
})
}
}
removeContact = (friend) => {
let index = this.state.contactsPicked.indexOf(friend)
let nextContacts = this.state.contactsPicked
let tempFriendsState = this.state.friendsState
tempFriendsState[friend.id] = false
nextContacts.splice(index,1)
console.log('removeContact'+friend.id);
this.setState({
contactsPicked: nextContacts,
friendsState: tempFriendsState,
})
}
_renderAddFriendTile = () => {
return(
<View style={[styles.step, styles.stepThree]}>
<View style={{flex:1}}>
<Text style={styles.heading}>Friend tile</Text>
</View>
{ (this.state.contactsPicked.length) > 0 ?
this.state.contactsPicked.map((contact,index) => (
<TouchableHighlight onPress={() => {this.removeContact(contact)}}>
<View>
<View key={index} style={[styles.row, styles.friendRow]}>
<Image source={contact.image} style={styles.friendIcon}></Image>
<Text style={styles.name}>{contact.firstname} </Text>
<Text style={styles.name}>{contact.surname}</Text>
<View style={styles.roundIconContainer}>
<View style={styles.roundIcon}>
<View style={[styles.removeButton, styles.buttonSmall]}>
<Image source={require('./images/redtree.jpg')} style={styles.crossIconSmall}></Image>
</View>
</View>
</View>
</View>
</View>
</TouchableHighlight>
))
: null
}
<TouchableHighlight style={styles.addFriendButtonContainer} onPress={() => {this.setModalVisible(true)}}>
<View style={styles.addFriendButton}>
<Text style={styles.addFriendButtonText}>Add friends</Text>
</View>
</TouchableHighlight>
</View>
)
}
render(){
return (
<ScrollView style={styles.container}>
<Modal
animationType={'fade'}
transparent={true}
visible={this.state.isModalVisible}
>
<View style={styles.addFriendModalContainer}>
<View style={styles.addFriendModal}>
<TouchableHighlight onPress={() => {this.setModalVisible(false)}}>
<View>
<Text>Close</Text>
</View>
</TouchableHighlight>
<ListView
dataSource={friends}
renderRow={(friend) => {
return (
<FriendRow
friend={friend}
pickContact={this.pickContact}
isSelected={this.state.friendsState[friend.id]}
/>
)
}}
/>
</View>
</View>
</Modal>
{this._renderAddFriendTile()}
</ScrollView>
)
}
}
class FriendRow extends Component {
constructor(props) {
super(props);
this.state = {
isSelected:this.props.isSelected,
}
}
componentDidMount(){
console.log('didmount');
}
render(){
var imageSource = (this.state.isSelected==true) ? require('./images/tree.jpg') : ''
console.log('friend'+!this.props.isSelected)
return(
<TouchableHighlight onPress={() => {this.props.pickContact(this.props.friend);this.setState({isSelected:!this.state.isSelected})}}>
<View style={[styles.row, styles.friendRow]}>
<Image source={this.props.friend.image} style={styles.friendIcon}></Image>
<Text style={styles.name}>{this.props.friend.firstname} </Text>
<Text style={styles.name}>{this.props.friend.surname}</Text>
<View style={styles.roundIconContainer}>
<View style={styles.roundIcon}>
<View style={this.state.isSelected ? [styles.buttonActive, styles.buttonSmall]: [styles.modalButtonInactive, styles.buttonSmall]}>
<Image source={imageSource} style={styles.buttonTickSmall}></Image>
</View>
</View>
</View>
</View>
</TouchableHighlight>
)
}
}

You can use filter method to filter out contacts if it's already there in view.
To remove contacts from view if already added:
this.setState({
...state,
contactsPicked: this.state.contactsPicked.filter((contactsPicked,index)=> index != pickedContactsIndex)
})

Firebase.push failed: first argument contains an invalid key($$typeof)

I am learning react native for the first time for developing android app not IOS one and I was learning from Building a Simple ToDo App With React Native and Firebase tutorial from youtube.But I am getting an error while trying to add items. I get following error
Firebase.push failed: first argument contains an invalid key($$typeof) in property 'restaurant.restaurant_name.targetInst._nativeParent._currentElement'.keys must be non-empty strings and cant contain ".","#","$","/","["
What might be creating this issue?
import React, { Component } from 'react';
import Firebase from 'firebase';
import {
AppRegistry,
StyleSheet,
Text,
View,
TouchableHighlight,
TextInput,
ListView
} from 'react-native';
class foodOrderSystem extends Component {
constructor(props){
super(props);
const firebaseRef = new Firebase('foodordersystem.firebaseio.com');
console.log(firebaseRef);
this.itemRef = firebaseRef.child('restaurant');
this.state = {
newRestaurant:'',
// estimated_delivery:'',
// description:'',
restaurantSource: new ListView.DataSource({rowHasChanged: (row1,row2) => row1 !== row2})
};
this.restaurant = [ ];
}
componentDidMount() {
this.itemRef.on('child_added', (snap) => {
this.restaurant.push({
id:snap.key(),
text:snap.val()
});
this.setState({
restaurantSource:this.state.restaurantSource.cloneWithRows(this.restaurant)
});
});
this.itemRef.on('child_removed', (snap) => {
this.restaurant = this.restaurant.filter((x) => x.id !== snap.key());
this.setState({
restaurantSource:this.state.restaurantSource.cloneWithRows(this.restaurant)
});
});
}
addRestaurant(){
if(this.state.newRestaurant !== ''){
this.itemRef.push({
restaurant_name: this.state.newRestaurant
});
this.setState({ newRestaurant:''});
}
}
removeRestaurant(rowData){
this.itemRef.child(rowData.id).remove();
}
render() {
return (
<View style={styles.appContainer}>
<View style={styles.titleView}>
<Text style={styles.titleText}>
foodOrderSystem
</Text>
</View>
<View style={styles.inputcontainer}>
<TextInput
style={styles.input}
onChange={(text) => this.setState({newRestaurant:text})}
value={this.state.newRestaurant} />
<TouchableHighlight
style={styles.button}
onPress={ () => this.addRestaurant() }
underlayColor="#00ffff">
<Text style={styles.btnText}>Add</Text>
</TouchableHighlight>
</View>
<ListView
dataSource={this.state.restaurantSource}
renderRow={this.renderRow.bind(this)} />
</View>
);
}
renderRow(rowData){
return(
<TouchableHighlight
underlayColor="#dddddd"
onPress={() => this.removeRestaurant(rowData)}>
<View>
<View style={styles.row}>
<Text style={styles.todoText}>{rowData.text}</Text>
</View>
<View style={styles.separator} />
</View>
</TouchableHighlight>
);
}
}
const styles = StyleSheet.create({
appContainer:{
flex: 1
},
titleView:{
backgroundColor: '#48afdb',
paddingTop: 30,
paddingBottom: 10,
flexDirection: 'row'
},
titleText:{
color: '#fff',
textAlign: 'center',
fontWeight: 'bold',
flex: 1,
fontSize: 20,
},
inputcontainer: {
marginTop: 5,
padding: 10,
flexDirection: 'row'
},
button: {
height: 36,
flex: 2,
flexDirection: 'row',
backgroundColor: '#48afdb',
justifyContent: 'center',
color: '#FFFFFF',
borderRadius: 4,
},
btnText: {
fontSize: 18,
color: '#fff',
marginTop: 6,
},
input: {
height: 36,
padding: 4,
marginRight: 5,
flex: 4,
fontSize: 18,
borderWidth: 1,
borderColor: '#48afdb',
borderRadius: 4,
color: '#48BBEC'
},
row: {
flexDirection: 'row',
padding: 12,
height: 44
},
separator: {
height: 1,
backgroundColor: '#CCCCCC',
},
todoText: {
flex: 1,
},
});
AppRegistry.registerComponent('foodOrderSystem', () => foodOrderSystem);
Here is the attachment of error