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React native, undefined is not an object And handle onChange

I made 2 screens home and editing screen. I want to change values from edit screen without redux and context but I don't know how? and also when I click save in editscreen it's throwing error that undefined is not an object (evaluating '_this.props.navigation.goBack') and displaing blank home screencwhy that's happening. Can some one help me please, below is my code
home.js
class Home extends Component {
state = {
modal: false,
editMode: false.
post: [
{
key: "1",
title: "A Good Boi",
des: "He's a good boi and every one know it.",
image: require("../assets/dog.jpg"),
},
{
key: "2",
title: "John Cena",
des: "As you can see, You can't see me!",
image: require("../assets/cena.jpg"),
},
],
};
addPost = (posts) => {
posts.key = Math.random().toString();
this.setState((prevState) => {
return {
post: [...prevState.post, posts],
modal: false,
};
});
};
onEdit = (data) => {
this.setState({ post: { title: data }, editMode: false });
};
render() {
if (this.state.editMode)
return <EditScreen item={item} onEdit={this.onEdit} />;
return (
<Screen style={styles.screen}>
<Modal visible={this.state.modal} animationType="slide">
<TouchableWithoutFeedback onPress={Keyboard.dismiss}>
<View style={styles.modalContainer}>
<AddPost addPost={this.addPost} />
</View>
</TouchableWithoutFeedback>
</Modal>
<FlatList
data={this.state.post}
renderItem={({ item }) => (
<>
<TouchableOpacity
activeOpacity={0.7}
onPress={() => this.setState({ editMode: true })}
style={styles.Edit}
>
<MaterialCommunityIcons
name="playlist-edit"
color="green"
size={35}
/>
</TouchableOpacity>
<Card>
<Image style={styles.image} source={item.image} />
<View style={styles.detailContainer}>
<Text style={styles.title} numberOfLines={1}>
{item.title}
</Text>
<Text style={styles.subTitle} numberOfLines={2}>
{item.des}
</Text>
</View>
</Card>
</>
)}
/>
</Screen>
Edit.js
import React, { Component } from "react";
import { View, StyleSheet, Image, KeyboardAvoidingView } from "react-native";
import colors from "../config/colors";
import AppButton from "../components/AppButton";
import AppTextInput from "../components/AppTextInput";
class EditScreen extends Component {
render() {
const { item, onEdit, onClose } = this.props;
return (
<KeyboardAvoidingView
behavior="position"
keyboardVerticalOffset={Platform.OS === "ios" ? 0 : 100}
>
<Image style={styles.image} source={item.image} />
<View style={styles.detailContainer}>
<AppTextInput value={item.title} />
<AppTextInput value={item.des} />
</View>
<AppButton
text="Save"
onPress={() => {
onEdit(this.state);
}}
/>
</KeyboardAvoidingView>
);
}
}
export default EditScreen;
AppTextInput.js
function AppTextInput({ icon, width = "100%", ...otherProps }) {
return (
<View style={[styles.container, { width }]}>
<TextInput
placeholderTextColor={defaultStyles.colors.medium}
style={defaultStyles.text}
{...otherProps}
/>
</View>
);
}

Try this:
Edit.js
import React, { Component } from 'react';
import { View, StyleSheet, Image, KeyboardAvoidingView } from 'react-native';
import colors from '../config/colors';
import AppButton from '../components/AppButton';
import AppTextInput from '../components/AppTextInput';
class EditScreen extends Component {
constructor(props) {
super(props);
this.state = { ...props.item };
}
render() {
const { onEdit, onClose } = this.props;
const { title, des, image } = this.state;
return (
<KeyboardAvoidingView
behavior="position"
keyboardVerticalOffset={Platform.OS === 'ios' ? 0 : 100}>
<Image style={styles.image} source={image} />
<View style={styles.detailContainer}>
<AppTextInput
value={title}
onChangeText={text => this.setState({ title: text })}
/>
<AppTextInput
value={des}
onChangeText={text => this.setState({ des: text })}
/>
</View>
<AppButton text="Save" onPress={() => onEdit(this.state)} />
</KeyboardAvoidingView>
);
}
}
export default EditScreen;
onEdit
onEdit = data => {
const newPosts = this.state.post.map(item => {
if(item.key === data.key) return data;
else return item;
})
this.setState({ post: newPosts, editMode: false });
};

Only the direct children of a navigator can access
this.props.navigation
If you want to access that inside the edit screen you can pass it from the Home screen as a prop. Like so:
return <EditScreen item={item} onEdit={this.onEdit} navigation={this.props.navigation} />;
But i don't think you need to go back because you are still on the Home page and just rendering the EditScreen within it. So just changing the state to have editMode: false should be enough

Both the parent and the child components get rendered simultaneously in react-native

I have a parent component that maps through an array of chapters and renders (an exercise) a child component for every item found and passes an array of exercises to it.
class ExercisesScreen extends Component {
showSelectedItemList = (screenName, text) => {
Navigation.push("ExercisesStack", {
component: {
name: screenName,
options: navOptionsCreator(text)
}
});
};
get chapters() {
return this.props.chapters.map(chapter => (
<TouchableOpacity key={chapter.id}>
<ExercisesList
onPress={() =>
this.showSelectedItemList(chapter.screenName, chapter.name)
}
exercises={chapter.exercises}
/>
</TouchableOpacity>
));
}
render() {
return <View>{this.chapters}</View>;
}
}
const mapStateToProps = state => ({
chapters: chaptersSelector(state)
});
When this child component receives the array of exercises, it maps through it and renders a list of exercises.
class ExercisesList extends Component {
render() {
return this.props.exercises.map(exercise => (
<View key={exercise.id}>
<TouchableOpacity
style={styles.button}
onPress={() =>
this.props.showSelectedItemList(exercise.screenName, exercise.name)
}
>
<Image source={exercise.icon}/>
<View>
<Text>{exercise.name}</Text>
</View>
<Image source={arrow} />
</TouchableOpacity>
<View />
</View>
));
}
}
ExercisesList.propTypes = {
onPress: PropTypes.func,
exercises: PropTypes.arrayOf(PropTypes.object)
};
The result I get from both components rendered simultaneously:
The question is, what should I do in order for them to render themselves separately and show the corresponding ExercisesList for every chapter in ExercisesScreen?

Make your child component ExercisesList as functional component that only show the corresponding ExercisesList for every chapter not perform any rendering.
Like below:
const ExercisesList = (props) => {
const { exercises } = props;
return({
exercises.map(exercise, index) => renderExcercise(exercise, index)
})
}
const renderExcercise = (exercise, index) => {
return(
<View key={exercise.id}>
<TouchableOpacity
style={styles.button}
onPress={() =>
this.props.showSelectedItemList(exercise.screenName, exercise.name)
}
>
<Image source={exercise.icon}/>
<View>
<Text>{exercise.name}</Text>
</View>
<Image source={arrow} />
</TouchableOpacity>
<View />
</View>
)
}
export default ExercisesList;
ExercisesList.propTypes = {
onPress: PropTypes.func,
exercises: PropTypes.arrayOf(PropTypes.object)
};

Pass state from component to Modal?

I have a component and import it in specific screen, in this screen i have a button when clicks i open modal contain component it's a "recorder" so after i record voices i want to take this voice and save them into Parent screen as a state or something!
in the recorder component, I save voices data into state! but how can i pass it to other parent screens!?
so how can I handle it?
here is shots
Parent Screen "after click add voice I show the modal"
Parent Screen
Here's a modal contain a recorder component
Modal
CODE
Component
" I pass data to PassDataToModal state inside componentDidMount "
import React, {Component} from 'react';
import {Platform, StyleSheet, Text, TouchableOpacity, View} from 'react-native';
import {AudioRecorder, AudioUtils} from 'react-native-audio';
import Sound from 'react-native-sound';
import Icon from 'react-native-vector-icons/MaterialIcons';
class RecorderScreen extends Component {
state = {
PassDataToModal: null,
};
componentDidMount() {
AudioRecorder.requestAuthorization().then(isAuthorised => {
this.setState({hasPermission: isAuthorised});
AudioRecorder.onFinished = data => {
console.log('data', JSON.stringify(data));
this.setState({PassDataToModal: data});
};
});
}
render() {
return (
<View style={styles.container}>
<View style={styles.controls}>
{this._renderPlayButton(() => {
this._play();
})}
{this._renderRecordButton(this.state.recording)}
{this._renderStopButton('Stop', () => {
this._stop().then(() => this.setState({currentTime: 0}));
})}
</View>
<Text style={styles.progressText}>{this.state.currentTime}s</Text>
</View>
);
}
}
export default RecorderScreen;
Parent Screen
import Modal from 'react-native-modal';
import RecorderScreen from './Recorder';
class Order extends Component {
constructor(props) {
super(props);
this.state = {
isModalVisible: false,
};
}
toggleModal = () => {
this.setState({isModalVisible: !this.state.isModalVisible});
};
render() {
return (
<View style={styles.container}>
<TouchableOpacity
onPress={this.toggleModal}
>
<Icon name="mic" color="#333" size={20} />
<Text style={{paddingHorizontal: 5}}>Add Voice</Text>
</TouchableOpacity>
<Modal
style={{margin: 0}}
isVisible={this.state.isModalVisible}
>
<View>
<TouchableOpacity onPress={this.toggleModal}>
<Icon name="close" color="#000" size={25} />
</TouchableOpacity>
<RecorderScreen /> // Component
</View>
</View>
)
}
}

In your parent component pass a function to your RecorderScreen component that will send the necessary data up. Docs on lifting state up.
So in your parent you'd have something like:
setData = (data) => {
// Set this to whatever you need it to be named
this.setState({childData: data});
}
Then pass the function as a prop:
<RecorderScreen setData={this.setData} />
And finally, call it in the child however needed (If I'm following the code something like this):
componentDidMount() {
AudioRecorder.requestAuthorization().then(isAuthorised => {
this.setState({hasPermission: isAuthorised});
AudioRecorder.onFinished = data => {
this.props.setData(data);
};
});
}
Then your parent component will have access to the child's data that you have lifted up.

How to send data from one screen to another screen in react native?

I am new to react native how can i send data from one screen to another screen using props in android not for ios my code is as below
Home.js
class Home extends React.Component {
constructor(props) {
super(props);
this.state = {
qwerty:{
data:[],
},
};
}
goPressed(navigate){
navigate("Product");
}
render() {
const { navigate } = this.props.navigation;
contents = this.state.qwerty.data.map((item) => {
return (
<View key={item.p1.id}>
<View>
<Text>{item.p1.content}</Text>
</View>
<View>
<TouchableHighlight onPress={() => this.goPressed(navigate)}>
<Text>
Go
</Text>
</TouchableHighlight>
</View>
</View>
);
});
return (
<ScrollView style={styles.container}>
{contents}
</ScrollView>
);
}
}
export default Home;
this is my home.js , I want pass data i.e {item.p1.content} to another screen i.e product.js so how can i do it what modification should i do?
Product.js
export default class Products extends Component {
static navigationOptions = {
title: "Products",
};
render() {
return (
<View style={{ flex: 1 }}>
<Text>{item.p1.content}</Text>
</View>
);
}
}

Send data to other screen
this.props.navigation.navigate('Your Screen Name' , { YourParamsName: "Foo"});
Receive data from other screen
this.props.navigation.state.params.YourParamsName

One method is to simply pass the date you are storing in 'qwerty' as a props to the next scene.
In Home.js you can modify your goPressed method to be something like...
goPressed(navigate){
navigate("Product", {passedData: this.state.qwerty.item.p1.content});
}
Then in Product.js you will need to modify the code to
render() {
return (
<View style={{ flex: 1 }}>
<Text>{this.props.passedData}</Text>
</View>
);
}

Programmatically add a component in React Native

Suppose I have a simple React Native app like so:
'use strict';
var React = require('react-native');
var {
AppRegistry,
Text,
TouchableHighlight,
View,
} = React;
var ReactProject = React.createClass({
_onPressOut: function() {
// What do we do here?
},
render() {
return (
<View>
<Text>This text should be before</Text>
<Text>This text should be after</Text>
<TouchableHighlight onPressOut={this._onPressOut}>
<Text>Tap Me</Text>
</TouchableHighlight>
</View>
);
}
});
AppRegistry.registerComponent('ReactProject', () => ReactProject);
How can I dynamically insert a component between the first and second Text tags when the TouchableHighlight is pressed?

Try creating an array and attaching it to the state. You can then push items to the array, and reset the state.
https://rnplay.org/apps/ymjNxQ
'use strict';
var React = require('react-native');
var {
AppRegistry,
StyleSheet,
Text,
View,
TouchableHighlight
} = React;
var index = 0
var SampleApp = React.createClass({
getInitialState(){
return { myArr: [] }
},
_onPressOut() {
let temp = index ++
this.state.myArr.push(temp)
this.setState({
myArr: this.state.myArr
})
},
render() {
let Arr = this.state.myArr.map((a, i) => {
return <View key={i} style={{ height:40, borderBottomWidth:2, borderBottomColor: '#ededed' }}><Text>{ a }</Text></View>
})
return (
<View style={styles.container}>
<Text>First</Text>
{ Arr }
<Text>Second</Text>
<TouchableHighlight style={ styles.button } onPress={ () => this._onPressOut() }>
<Text>Push</Text>
</TouchableHighlight>
</View>
);
}
});
var styles = StyleSheet.create({
container: {
flex: 1,
marginTop:60
},
button: {
height:60,
backgroundColor: '#ededed',
marginTop:10,
justifyContent: 'center',
alignItems: 'center'
}
});
AppRegistry.registerComponent('SampleApp', () => SampleApp);
I've set up a working example here.

In react or react native the way component hide/show or add/remove does not work like in android or iOS. Most of us think there would be the similar stratedgy like
View.hide = true or parentView.addSubView(childView
But the way react native work is completely different. The only way to acheive this kind of functionality is to include your component in your DOM or remove from DOM.
Here in this example I am going set the visibility of text view based on the button click.
enter image description here
The idea behind this task is the create a state variable called state having the initial value set to false when the button click event happens then it value toggles. Now we will use this state variable during the creation of component.
import renderIf from './renderIf'
class fetchsample extends Component {
constructor(){
super();
this.state ={
status:false
}
}
toggleStatus(){
this.setState({
status:!this.state.status
});
console.log('toggle button handler: '+ this.state.status);
}
render() {
return (
<View style={styles.container}>
{renderIf(this.state.status)(
<Text style={styles.welcome}>
I am dynamic text View
</Text>
)}
<TouchableHighlight onPress={()=>this.toggleStatus()}>
<Text> touchme </Text>
</TouchableHighlight>
</View>
);
}
}
the only one thing to notice in this snippet is renderIf which is actually a function which will return the component passed to it based on the boolean value passed to it.
renderIf(predicate)(element).
renderif.js
'use strict';
const isFunction = input => typeof input === 'function';
export default predicate => elemOrThunk =>
predicate ? (isFunction(elemOrThunk) ? elemOrThunk() : elemOrThunk) : null;

With React components you don't want to think of actions reaching into the DOM and inserting components - you want to think components responding to actions. Theoretically, this component is already composed and ready, it just needs to know if it should be rendered or not:
var ReactProject = React.createClass({
getInitialState() {
// our *state* dictates what the component renders
return {
show: false
};
}
_onPressOut: function() {
// update our state to indicate our "maybe" element show be shown
this.setState({show: !this.state.show});
},
maybeRenderElement() {
if (this.state.show) {
// depending on our state, our conditional component may be part of the tree
return (
<Text>Yay!</Text>
);
}
return null;
}
render() {
return (
<View>
<Text>This text should be before</Text>
{this.maybeRenderElement()}
<Text>This text should be after</Text>
<TouchableHighlight onPressOut={this._onPressOut}>
<Text>Tap Me</Text>
</TouchableHighlight>
</View>
);
}
});
I've also made a helper that makes it easy to conditionally render things, render-if
renderIf(this.state.show)(
<Text>Yay</Text>
)

ECMA6 Syntax
import React, { Component } from 'react';
import {
View,
Text,
StyleSheet,
TextInput,
TouchableOpacity,
TouchableHighlight
} from 'react-native';
export default class fourD extends Component {
constructor(props) {
super(props);
let ele1 = (
<View key={1}>
<Text>Element {1}</Text>
<TouchableOpacity onPress={ () => this._add() }>
<Text>Add</Text>
</TouchableOpacity>
</View>
);
this.state = {
ele: [],
key: 1
}
this.state.ele.push(ele1);
}
_add(){
let key = this.state.key + 1;
let ele2 = (
<View key={key}>
<Text>Element {key}</Text>
<TouchableOpacity onPress={ () => this._add() }>
<Text>Add</Text>
</TouchableOpacity>
</View>
);
let ele = this.state.ele;
ele.push(ele2);
this.setState({ ele: ele,key : key})
}
render() {
return (
<View style={styles.container}>
<Text>This text should be before</Text>
{ this.state.ele }
<Text>This text should be after</Text>
<TouchableHighlight onPressOut={ () => this._add() }>
<Text>Tap Me</Text>
</TouchableHighlight>
</View>
)
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: "white",
}
})