So im new at react native and i built an custom text input that gives suggestions by following a tutorial.But now i cant use onChange in that custom text input.I tried to create a state in App.js and change it in AutoCompleteText.js file but didnt worked.How can i get the value inmy custom text input ?
my App.js file :
import { StatusBar } from 'expo-status-bar';
import React from 'react';
import { StyleSheet, Text, View } from 'react-native';
import AutoCompleteText from './AutoCompleText'
import './AutoCompleteText.css';
export default function App() {
return (
<View style={styles.container}>
<View style={styles.AutoComp}>
<AutoCompleteText items={['Ali','Veli','Ahmet']} />
</View>
<StatusBar style="auto" />
</View>
);
}
const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: '#fff',
alignItems: 'center',
justifyContent: 'center',
},
AutoComp:{
width:600
}
});
my AutoCompleteText.js file
import React from 'react'
import './AutoCompleteText.css';
export default class AutoCompleteText extends React.Component{
constructor(props){
super(props);
this.state={
suggestions:[],
text:'',
};
}
onTextChanged = (e) =>{
const {items} = this.props;
const value = e.target.value;
let suggestions = [];
if (value.length > 0){
const regex = new RegExp(`^${value}`,'i');
suggestions = items.sort().filter(v => regex.test(v));
}
this.setState(() => ({ suggestions , text: value }));
}
suggestionSelected(value){
this.setState(() =>({
text: value,
suggestions:[],
}) )
}
renderSuggestions(){
const {suggestions} = this.state;
if (suggestions.length === 0){
return null;
}
return(
<ul>
{suggestions.map((item) => <li onClick={() => this.suggestionSelected(item)}>{item}</li>)}
</ul>
);
}
render(){
const { text } = this.state;
return(
<div className="AutoCompleteText">
<input value={text} onChange={this.onTextChanged} type ='text'/>
{this.renderSuggestions()}
</div>
)
}
}
hi Ülkü Tuncer Küçüktaş,
You are writing the wrong syntax. You are mixing the syntax of react native with react. In react native for textinput, you should use the TextInput Component(Built in component from docs).
The syntax of react native TextInput look like below
import React from 'react';
import { TextInput } from 'react-native';
const UselessTextInput = () => {
const [value, onChangeText] = React.useState('Useless Placeholder');
return (
<TextInput
style={{ height: 40, borderColor: 'gray', borderWidth: 1 }}
onChangeText={text => onChangeText(text)}
value={value}
/>
);
}
export default UselessTextInput;
Related
I'm working on a code that will give a TodoList in React-Native, my code doesn't create an error but when I want to change a label, the code duplicates my state. I can't find where is my mistake, can someone help me please?
Apps.js
`
import React, {Component, useState} from 'react';
import {View,Text,Button, StyleSheet} from 'react-native';
import TodoList from './TodoList';
class Apps extends Component {
state={
todos:[
{id:1,label:'Buy some milk'},
{id:2,label:'Learn some React'}
]
}
newTodo = ()=>{
this.setState({count:this.state.count+1})
this.setState({todos:[...this.state.todos,...[{id:this.state.count+1,label:'New Task'}]]})
}
updateTodoLabel=(todoId,label)=>{
const{todos}=this.state
const todoIndex=todos.findIndex(t=>t.id===todoId)
const todosBefore=todos.slice(0,todoIndex)
const todosAfter=todos.slice(todoIndex+1)
const newtodo={...todos[todoIndex],label}
this.setState({
todos:[...todosBefore,newtodo,...todosAfter]
})
}
render(){
const {todos} = this.state
return(
<View style={styles.container}>
<TodoList todos={todos} updateTodoLabel={this.updateTodoLabel}/>
<Button title="Add" onPress={this.newTodo}/>
</View>
)
}
}
// ...
const styles=StyleSheet.create({
container:{
flex:1,
marginTop:25
}
})
export default Apps
`
Todo.js
`
//src/components/Todo.js
import { Component, Fragment } from 'react';
import {
View,
Text,
StyleSheet,
Button,
TextInput,
TouchableOpacity,
} from 'react-native';
class Todo extends Component {
state = {
editMode: false,
label: this.props.todo.label,
};
renderEditMode = () => {
const { label } = this.state;
return (
<Fragment>
<TextInput
style={[styles.editInput, styles.todoLabel]}
value={label}
onChangeText={this.onChange}
autoFocus
/>
<Button title="Save" onPress={this.onSavePress} />
<Button title="Cancel" onPress={this.onCancelPress} />
</Fragment>
);
};
onPressButton = () => {
const { updateTodoLabel } = this.props;
const { label } = this.state;
updateTodoLabel(label + '✅');
this.setState({
editMode: false,
});
};
render() {
const { editMode } = this.state;
return (
<View style={styles.todo}>
{editMode ? this.renderEditMode() : this.renderViewMode()}
</View>
);
}
renderViewMode = () => {
const { todo } = this.props;
return (
<Fragment>
<TouchableOpacity onPress={this.onPressButton}>
<Text style={styles.todoLabel}>{todo.label}</Text>
</TouchableOpacity>
<Button title="Edit" onPress={this.onEditPress} />
</Fragment>
);
};
onEditPress = () => {
this.setState({
editMode: true,
});
};
onChange = (label) => {
this.setState({ label });
};
onSavePress = () => {
const { updateTodoLabel } = this.props;
const { label } = this.state;
updateTodoLabel(label);
this.setState({
editMode: false,
});
};
onCancelPress = () => {
this.setState({
editMode: false,
label: this.props.todo.label,
});
};
}
const styles = StyleSheet.create({
todo: {
padding: 10,
borderTopWidth: 1,
borderStyle: 'solid',
borderColor: 'lightgray',
},
todoLabel: {
fontSize: 18,
padding: 10,
flex: 1,
},
});
export default Todo;
`
TodoList.js
`
//src/components/TodoList.js
import React from 'react';
import {View, StyleSheet,Button} from 'react-native';
import Todo from './Todo';
const TodoList=({todos, updateTodoLabel})=>(
<View style={styles.todoList}>
{todos.map(todo =>(
<Todo
todo={todo}
updateTodoLabel={label=>updateTodoLabel(todo.id,label)}
key={todo.id}/>
))}
</View>
)
const styles = StyleSheet.create({
todoList:{
flex:1,
alignItems:'stretch'
}
})
export default TodoList
`
I trying to give a precise way of the label or to just change the label and to change the old state by the new state but I'm a beginner and I only found errors in this ways.
I found my error, that's was only a mistake on the todos of my state in the Apps.js, I need to get a count:2 after the todos.
state={
todos:[
{id:1,label:'Buy some milk'},
{id:2,label:'Learn some React'}
],count:2
}
The intended function is that it would just delete the one goal that is clicked but for some odd reason it decides onPress to delete all goals listed.
I am following this tutorial https://www.youtube.com/watch?v=qSRrxpdMpVc and im stuck around 2:44:45. If anyone else has done this tutorial and or can see my problem an explanation would be greatly appreciated. :)
Program
import React, { useState } from "react";
import {
StyleSheet,
Text,
View,
Button,
TextInput,
ScrollView,
FlatList
} from "react-native";
import GoalItem from "./components/GoalItem";
import GoalInput from "./components/GoalInput";
export default function App() {
const [courseGoals, setCourseGoals] = useState([]);
const addGoalHandler = goalTitle => {
setCourseGoals(currentGoals => [
...currentGoals,
{ key: Math.random().toString(), value: goalTitle }
]);
};
const removeGoalHander = goalId => {
setCourseGoals(currentGoals => {
return currentGoals.filter((goal) => goal.id !== goalId);
});
};
return (
<View style={styles.screen}>
<GoalInput onAddGoal={addGoalHandler} />
<FlatList
keyExtractor={(item, index) => item.id}
data={courseGoals}
renderItem={itemData => (
<GoalItem
id={itemData.item.id}
onDelete={removeGoalHander}
title={itemData.item.value}
/>
)}
></FlatList>
</View>
);
}
const styles = StyleSheet.create({
screen: {
padding: 80
}
});
Function
import React from "react";
import { View, Text, StyleSheet, TouchableOpacity } from "react-native";
const GoalItem = props => {
return (
<TouchableOpacity onPress={props.onDelete.bind(this, props.id)}>
<View style={styles.listItem}>
<Text>{props.title}</Text>
</View>
</TouchableOpacity>
);
};
const styles = StyleSheet.create({
listItem: {
padding: 10,
backgroundColor: "lightgrey",
borderColor: "grey",
borderRadius: 5,
borderWidth: 1,
marginVertical: 10
}
});
export default GoalItem;
When updating state, you have to pass new array so component can detect changes and update view
const removeGoalHander = goalId => {
setCourseGoals(currentGoals => {
const newGoals = currentGoals.filter((goal) => goal.id !== goalId);
return [...newGoals];
});
};
According to this link in the React Native API Documents:
https://facebook.github.io/react-native/docs/0.59/textinput#isfocused
The TextInput component has a method called isFocused(). How would I go about accessing this method? Do I have to use a ref?
Also, I already know that I can achieve the same effect by using the onFocus prop and setting up a state manager and a function to change the state of the input based on the onFocus. However, I am just curious how I would go about using these component methods since there are others in other components as well.
I have tried using this
<TextInput onChangeText={this.handleText} style={(this.isFocused()) ? styles.input : styles.lame} placeholder="Names"/>
but it is looking like I might have to use a ref since it seems that it isn't defined even though the method should be a part of this component.
isFocused() should be called on ref to TextInput.
import React, {useEffect, useRef} from 'react';
import {TextInput, BackHandler} from 'react-native';
function SearchBar() {
const textInputReference = useRef(null);
useEffect(() => {
let backhandler = BackHandler.addEventListener(
'hardwareBackPress',
function() {
if (textInputReference.current.isFocused()) {
textInputReference.current.blur();
return true;
}
return false;
},
);
return () => {
backhandler.remove();
};
}, []);
return (
<TextInput ref={textInputReference} />
);
}
export default SearchBar;
You can use state for handle input focus, if you have multi-input that also need focus state, just create many state for it.
class MyComponent extends React.Component {
state = { isFocused: false }
handleInputFocus = () => this.setState({ isFocused: true })
handleInputBlur = () => this.setState({ isFocused: false })
render() {
const { isFocused } = this.state
return (
<View>
<TextInput
onFocus={this.handleInputFocus}
onBlur={this.handleInputBlur}
style={ isFocused ? styles.input : styles.lame}
/>
<Text>Hello World</Text>
</View>
)
}
}
This another easy way to use the onFocus prop in TextInput
import React, { useState } from 'react'
import { View, StyleSheet, TextInput } from 'react-native'
const TextInput = () => {
const [isHighlighted, setIsHighlighted] = useState(false)
return (
<View>
<TextInput
style={[styles.textInput, isHighlighted && styles.isHighlighted]}
onFocus={() => { setIsHighlighted(true)}
onBlur={() => {setIsHighlighted(false)} />
</View>
)
}
const styles = StyleSheet.create({
textInput: {
borderColor: 'grey',
borderWidth: StyleSheet.hairlineWidth,
borderRadius: 8,
height: 43,
},
isHighlighted: {
borderColor: 'green',
}
})
According to its documentation
Returns true if the input is currently focused; false otherwise.
How we can achieve that? the answer is useRef.
For example :
import React, { useRef } from 'react'
import { View, StyleSheet, TextInput, Button } from 'react-native'
const App = props => {
const inputRef = useRef(null);
const checkIsFocusedHandler = () => {
const result = inputRef.current.isFocused();
alert(result);
}
return (
<View style={styles.container}>
<TextInput ref={inputRef} style={styles.input} value="Abolfazl Roshanzamir" />
<TextInput style={styles.input} />
<Button title="Check isFocused" onPress={checkIsFocusedHandler} />
</View>
)
}
If we click on the first TextInput then click on the button, the result is => true,
if we click on the second TextInput then click on the button, the result is => false.
Use onFocus props of TextInput component
<TextInput onFocus={yourCallBack} />
yourCallBack function will be called when the TextInput is focused
I am new at React Native.
I'm working on a code that will change the background color of a box (card) according to the data that I will get from API. I want to check first if the title is like 'Taylor' make background red , if it is 'Fearless' make it green and so on.
Here is the API that I got information from :
http://rallycoding.herokuapp.com/api/music_albums
This is the code divided into several files.
First of them index.js
// Import a library to help to create a component
import React from 'react';
import { Text, AppRegistry, View } from 'react-native';
import Header from './src/components/header.js';
import AlbumList from './src/components/AlbumList.js'
// create a component
const App = () => (
<View>
<Header headerText={'Smart Parking'}/>
<AlbumList />
</View>
);
//render it to the device
AppRegistry.registerComponent('albums2', () => App);
second is AlbumList.js
import React, { Component } from 'react';
import { View } from 'react-native';
import axios from 'axios';
import AlbumDetail from './AlbumDetail.js'
class AlbumList extends Component {
state = { albums: [] };
componentWillMount() {
axios.get('https://rallycoding.herokuapp.com/api/music_albums')
.then(response => this.setState({ albums: response.data }) );
}
renderAlbums() {
return this.state.albums.map(album =>
<AlbumDetail key={album.title} album={album} />
);
}
render() {
return(
<View>
{this.renderAlbums()}
</View>
);
}
}
export default AlbumList;
3rd is AlbumDetail.js
import React from 'react';
import {Text, View} from 'react-native';
import Card from './Card.js'
const AlbumDetail = (props) => {
return(
<Card>
<Text> {props.album.title} </Text>
</Card>
);
};
export default AlbumDetail;
4th is card which I need to change background of it
import React from 'react';
import { View } from 'react-native';
const Card = (props) => {
return (
<View style={styles.containerStyle}>
{props.children}
</View>
);
};
const styles = {
containerStyle:{
borderWidth: 1,
borderRadius: 2,
backgroundColor: '#ddd',
borderBottomWidth: 0,
shadowColor: '#000',
shadowOffset: {width: 0, height:2 },
shadowOpacity: 0.1,
shadowRadius: 2,
elevation: 1,
marginLeft: 5,
marginRight: 5,
marginTop: 10
}
};
export default Card;
last one is header
// Import libraries for making components
import React from 'react';
import { Text, View } from 'react-native';
// make a components
const Header = (props) => {
const { textStyle, viewStyle } = styles;
return(
<View style={viewStyle}>
<Text style={textStyle}>{props.headerText}</Text>
</View>
)
};
const styles ={
viewStyle:{
backgroundColor:'orange',
justifyContent: 'center',
alignItems: 'center',
height: 60,
},
textStyle: {
fontSize: 20
}
};
// make the component to the other part of the app
export default Header;
Basically you need to pass the title of the album as prop to the Card from the AlbumDetails component and then on each Card calculate the color to use and pass it in the style like this:
// AlbumDetails.js component
import React from 'react';
import {Text, View} from 'react-native';
import Card from './Card.js'
const AlbumDetail = (props) => {
return(
<Card title={props.album.title}>
<Text> {props.album.title} </Text>
</Card>
);
};
export default AlbumDetail;
// Card.js component
import React from "react";
import { View } from "react-native";
function calculateColor(title) {
let bgColor;
switch (title) {
case "Taylor":
bgColor = "red";
break;
case "Fearless":
bgColor = "green";
break;
default:
bgColor = "orange";
break;
}
return bgColor;
}
const Card = props => {
const { title } = props;
const backgroundColor = calculateColor(title);
return (
<View style={[styles.containerStyle, { backgroundColor: backgroundColor }]}>
{props.children}
</View>
);
};
const styles = {
containerStyle: {
borderWidth: 1,
borderRadius: 2,
backgroundColor: "#ddd",
borderBottomWidth: 0,
shadowColor: "#000",
shadowOffset: { width: 0, height: 2 },
shadowOpacity: 0.1,
shadowRadius: 2,
elevation: 1,
marginLeft: 5,
marginRight: 5,
marginTop: 10
}
};
export default Card;
Something like this should work:
Change the AlbumDetail to conditionally render the Card.
const AlbumDetail = props => {
if (props.album.title === 'Taylor') {
return (
<Card style={{ backgroundColor: 'red' }}>
<Text>{props.album.title}</Text>
</Card>
);
} else {
return (
<Card style={{ backgroundColor: 'green' }}>
<Text>{props.album.title}</Text>
</Card>
);
}
};
Override the default style of the card using the passed style prop.
const Card = props => {
return (
<View style={[styles.containerStyle, props.style]}>{props.children}</View>
);
};
accepted answer is great just its a bad habit to do things in render.
i also not sure since every title has a color why wouldnt the server send this in the object props in first place ? :)
class AlbumList extends Component {
state = { albums: [] };
componentDidMount() {
axios.get('https://rallycoding.herokuapp.com/api/music_albums')
.then(response=> Array.isArray(response.data) ? response.data : []) // alittle validation would not hurt :) !
.then(data => this.setState({ albums: data }) );
}
selectHeaderColorForAlbum( album ){
let headerColor = 'red';
// switch(album.title){ ..you logic }
return headerColor;
}
renderAlbums() {
return this.state.albums.map(album =>
<AlbumDetail key={album.title} album={album} color={this.selectHeaderColorForAlbum(album)} />
);
}
render() {
return(
<View>
{this.renderAlbums()}
</View>
);
}
}
const Card = (props) => {
return (
<View style={[styles.containerStyle,{color:props.headerColor}]}>
{props.children}
</View>
);
};
this is easier your logic will render only once.
also notice that react >16.0 depricated componentWillMount, so use DidMount
I'm an iOS developer currently working on an experimental React Native app.
I have the following code which shows a button and sample text on the screen.
import React from 'react';
import { StyleSheet, Text, View , Button } from 'react-native';
export default class App extends React.Component {
constructor() {
super();
this.state = {sampleText: 'Initial Text'};
}
changeTextValue = () => {
this.setState({sampleText: 'Changed Text'});
}
_onPressButton() {
<Text onPress = {this.changeTextValue}>
{this.state.sampleText}
</Text>
}
render() {
return (
<View style={styles.container}>
<Text onPress = {this.changeTextValue}>
{this.state.sampleText}
</Text>
<View style={styles.buttonContainer}>
<Button
onPress={this._onPressButton}
title="Change Text!"
color="#00ced1"
/>
</View>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
backgroundColor: '#f5deb3',
alignItems: 'center',
justifyContent: 'center',
},
buttonContainer: {}
});
The above code displays text and a button.
However when I click the button, the app crashes instead of showing the new text which is to be shown.
I'm new to React Native, kindly guide me on how to solve the error.
You could use a state to keep your default text and then on press we update the state.
import React, { Component } from 'react'
import { View, Text, Button } from 'react-native'
export default class App extends Component {
state = {
textValue: 'Change me'
}
onPress = () => {
this.setState({
textValue: 'THE NEW TEXT GOES HERE'
})
}
render() {
return (
<View style={{paddingTop: 25}}>
<Text>{this.state.textValue}</Text>
<Button title="Change Text" onPress={this.onPress} />
</View>
)
}
}
You can use state for dynamically change the text
import React, {Component} from 'react';
import {Text, Button, View} from 'react-native';
export default class App extends Component{
constructor(){
super();
this.state = {
textValue: 'Temporary text'
}
this.onPressButton= this.onPressButton.bind(this);
}
onPressButton() {
this.setState({
textValue: 'Text has been changed'
})
}
render(){
return(
<View style={{paddingTop: 20}}>
<Text style={{color: 'red',fontSize:20}}> {this.state.textValue} </Text>
<Button title= 'Change Text' onPress= {this.onPressButton}/>
</View>
);
}
}
With hooks:
import React, {useState} from "react";
import {Button, Text, View} from "react-native";
const App = () => {
const [text, setText] = useState("Initial text");
const onPressHandler = event => setText("Changed text");
return (
<View>
<Text>{text}</Text>
<Button title="Change Text" onPress={onPressHandler} />
</View>
);
};
You better make sure what _onPressButton() is doing. You can simply setState() in this function and do nothing else, which can help you solve the problem. If you want to render something new, you have to add return() and wrap up Text.
You can use this approach for updating a value on click of a button
class App extends React.Component {
constructor() {
super();
this.state = { val: 0 }
this.update = this.update.bind(this)
}
update() {
this.setState({ val: this.state.val + 1 })
}
render() {
console.log('render');
return <button onClick={this.update}>{this.state.val}</button>
}
}
It's because your onPress function is a little weird, you want to invoke an action on press, not have jsx elements. Your changeTextValue is what should be passed into your button's onPress.
Set my text in state method then update state in pressed button, then set in text like this:
<Text>
{this.state.myText}
</Text>
import React, { useState } from "react";
import { View, Text } from "react-native";
const App = () => {
const [value, setValue] = useState("Mohd Sher Khan");
const hellod = () => {
setValue("value changed");
};
return (
<View>
<Text onPress={hellod}>{value}</Text>
</View>
);
};
export default App;