I am trying to implement a recursive method on reactjs, but only when data is submitted or clicked.
Following is the code I am trying with:
import React, { Component } from "react";
class Textbox extends React.Component {
constructor(props) {
super(props);
this.state = {value: ''};
this.handleChange = this.handleChange.bind(this);
this.handleSubmit = this.handleSubmit.bind(this);
}
handleChange(event) {this.setState({value: event.target.value}); }
handleSubmit(event) {
alert('A name was submitted: ' + this.state.value);
event.preventDefault();
}
render() {
return (
<form onSubmit={this.handleSubmit}>
<div>
<label>
Name:
<input type="text" value={this.state.value} onChange={this.handleChange} />
</label>
<input type="submit" value="React" />
</div>
</form>
);
}
}
export default Textbox;
which generates the following view.
I want to use a recursive method onClick or onSubmit, such that it will generate another text box upon submission. Like
which I want to continue until I click some "Exit" or "Stop" button, which I can add to the top of the view.
From what I have read about recursive implementation on ReactJS, I need to call the class/function again inside render. When I do that I think react is getting inside the infinite loop and freezes the browser.
what I tried is to call Textbox inside the <div> <div/> of the render method. Like this:
.... other code lines are same
<div>
<label>
Name:
<input type="text" value={this.state.value} onChange={this.handleChange} />
</label>
<input type="submit" value="React" />
<Textbox/>
</div>
How can I generate a recursive textbox on submission/clicking event on the previous text box?
You could do it like this, where showNextInput prevents the infinite loop:
class Textbox extends React.Component {
constructor(props) {
super(props);
this.state = {
value: '',
showNextInput: false,
};
this.handleChange = this.handleChange.bind(this);
this.handleSubmit = this.handleSubmit.bind(this);
}
handleChange(event) {this.setState({value: event.target.value}); }
handleSubmit(event) {
console.log('submit');
event.preventDefault();
this.setState({ showNextInput: true });
}
render() {
return (
<>
<form onSubmit={this.handleSubmit}>
<div>
<label>
Name:
<input type="text" value={this.state.value} onChange={this.handleChange} />
</label>
<input type="submit" value="Submit" />
</div>
</form>
{ this.state.showNextInput ? <Textbox/> : null }
</>
);
}
}
However, your use case looks like something you would usually do by
managing a list of values somewhere,
add items as required inside your handlers, and
then display a list of these items
Here a quick and dirty example:
export class TextboxList extends React.Component {
constructor(props) {
super(props);
this.state = {
values: {
0: ''
},
};
this.handleChange = this.handleChange.bind(this);
this.handleSubmit = this.handleSubmit.bind(this);
}
handleChange(index, value) {
this.setState({
values: {
...this.state.values,
[index]: value
}
});
}
handleSubmit(event) {
event.preventDefault();
this.setState({
values: {
...this.state.values,
[Object.keys(this.state.values).length]: '' // add new empty item to list
}
});
}
render() {
return (
<>
<form onSubmit={this.handleSubmit}>
{ Object.keys(this.state.values).map( (index) => {
const value = this.state.values[index];
return <div key={ index }>
<label>
Name:
<input
type="text"
value={ value }
onChange={ (event) => this.handleChange( index, event.target.value ) }
/>
</label>
<input type="submit" value="Submit" />
</div>;
})}
</form>
</>
);
}
}
export default Textbox;
Related
I have a generic Todo List built in React. Each task from user input is stored in tasks array declared in parent component <ReactTodoApp />. Tasks are rendered in child component <TodoList />. A unique key is assigned to each task in DOM element <label />. When inspecting dev tools unique ids are generating, however error is still present.
Would anyone know why I am still getting the "unique key prop" error?
Link to working application: https://codesandbox.io/s/todo-list-34udn?file=/src/App.js
JS file:
import React, { Component } from "react";
import "./styles.css";
export default class ReactTodoApp extends Component {
constructor(props) {
super(props);
this.state = {
//container for new task
input: "",
tasks: []
};
this.handleChange = this.handleChange.bind(this);
this.handleSubmit = this.handleSubmit.bind(this);
this.handleRemove = this.handleRemove.bind(this);
}
handleChange(event) {
this.setState({ input: event.target.value });
}
handleSubmit(event) {
event.preventDefault();
//condition for empty empty
if (!this.state.input) {
return;
}
//declare object to store
const newTask = {
input: this.state.input,
id: 1 + Math.random()
};
//request update to current tasks state
this.setState((state) => ({
tasks: state.tasks.concat(newTask),
input: ""
}));
}
//updater function to remove task
handleRemove(props) {
//create new task list
const newTasksList = this.state.tasks;
//remove selected item from new task list
newTasksList.splice(props, 1);
//update state for tasks
this.setState({ tasks: newTasksList });
}
render() {
return (
<div>
<h1>React Todo</h1>
<form onSubmit={this.handleSubmit} className="add-item">
<input
type="text"
value={this.state.input}
onChange={this.handleChange}
className="add-item__input"
placeholder="new item"
/>
<button type="submit" className="submit">
add item
</button>
</form>
<TodoList tasks={this.state.tasks} handleRemove={this.handleRemove} />
</div>
);
}
}
class TodoList extends React.Component {
render() {
return (
<div className="list-container">
{this.props.tasks.map((task) => (
<label keys={task.id} className="item-container">
<input type="checkbox" />
<p className="item__text">{task.input}</p>
<button onClick={this.props.handleRemove} className="remove-button">
x
</button>
<span className="custom-checkbox" />
</label>
))}
</div>
);
}
}
Just change keys={task.id} to key={task.id}
I have two files which work together to render things. The first is App.js, which first renders Form.js. The form will then collect information, which on submission, changes the Form state and calls a function from App.js. This function is called "createProject." Calling "createProject" in Form.js "handleSubmit" makes the page auto-refresh. However, if I remove "createProject" from handleSubmit, the page does not auto-refresh. Here are the two files.
import React, { Component } from "react";
import Project from "./components/Project.js"
import Form from "./Form.js";
class App extends Component {
constructor(props) {
super(props);
this.state = {
projectList: [],
myProjects: [],
userList: [],
submitted: false
};
this.createProject = this.createProject.bind(this);
}
createProject(title, desc, langs, len, exp) {
this.setState({
projectList: this.state.projectList.push([
{
title : title,
description : desc,
language : langs,
length : len,
experience : exp
}
]),
submitted : true
});
}
deleteProject(title) {
const projects = this.state.projectList.filter(
p => p.title !== title
);
this.setState({projects});
}
render() {
let info;
if (this.state.submitted) {
info = (
<div>
<p>cccc</p>
</div>
);
} else {
info = (
<br/>
);
}
return(
<div>
<Form/>
{info}
{this.state.projectList.map((params) =>
<Project {...params}/>)}
</div>
);
}
}
export default App;
import React from "react";
import createProject from "./App.js"
class Form extends React.Component {
constructor(props) {
super(props);
this.state = {
title: "",
description: "",
language: "",
length: 0,
experience: "",
submitted: false
};
this.handleSubmit = this.handleSubmit.bind(this);
this.handleInputChange = this.handleInputChange.bind(this);
}
handleSubmit(event) {
this.setState({
submitted: true
})
createProject(
this.state.title,
this.state.description,
this.state.language,
this.state.length,
this.state.experience
)
event.preventDefault();
}
handleInputChange(event) {
const target = event.target;
const value = target.value;
const name = target.name;
this.setState({
[name]: value
});
}
render() {
let info;
if (this.state.submitted) {
info = (
<div>
<h1>{this.state.title}</h1>
<p>{this.state.description}</p>
<p>{this.state.language}</p>
<p>{this.state.length}</p>
<p>{this.state.experience}</p>
</div>
);
} else {
info = <br/>;
}
return (
<div>
<form onSubmit={this.handleSubmit}>
<label>
Title:
<input
name="title"
type="textbox"
checked={this.state.title}
onChange={this.handleInputChange} />
</label>
<br />
<label>
Description:
<input
name="description"
type="textbox"
checked={this.state.description}
onChange={this.handleInputChange} />
</label>
<br />
<label>
Language:
<input
name="language"
type="textbox"
checked={this.state.language}
onChange={this.handleInputChange} />
</label>
<br />
<label>
Length:
<input
name="length"
type="number"
checked={this.state.length}
onChange={this.handleInputChange} />
</label>
<br />
<label>
Experience:
<input
name="experience"
type="textbox"
checked={this.state.experience}
onChange={this.handleInputChange} />
</label>
<br />
<input type="submit" value="Submit" />
</form>
{info}
</div>
);
}
}
export default Form;
I've also tried adding "new" to the "createProject" in handleSubmit, and while that does stop the auto-refresh, it will not call the createProject function. (Or maybe it does, but none of the code in the createProject function seems to be run.) Can anyone help with preventing this auto refresh while also allowing App's createProject function to run properly?
The page auto refreshes because execution never gets to your event.PreventDefault() line. This is due to an error encountered when react tries to evaluate createProject. To fix this, correct handleSubmit like so.
handleSubmit(event) {
event.preventDefault(); // moved up in execution.
this.setState({
submitted: true
})
createProject(
this.state.title,
this.state.description,
this.state.language,
this.state.length,
this.state.experience
)
}
Notice that moving event.PreventDefault() to the top of your handleSubmit(event) function just before this.setState line prevents default form behaviour on submit.
You however get an error because App.js doesn't export a function called createProject. To maintain the createProject within App instance, you need to pass it as a prop which you can then reference as this.props.createProject.
See this answer on how to do call a Parent method in ReactJS.
Trying to set up something simple.
Parent: app.js
class App extends React.Component {
constructor(props) {
super(props);
//This acts as our global state
this.state = {
username: "",
email: "",
bio: ""
};
}
componentDidMount() {
setTimeout(() => {
this.setState({
username: "jonny",
email: "jonny#mail.com",
bio: "My bio...."
});
}, 5000);
}
handleFormChange = data => {
this.setState(data);
};
render() {
return (
<div className="App">
<h1>Hello CodeSandbox</h1>
<Form data={this.state} onHandleFormChange={this.handleFormChange} />
<p>Name from App state: {this.state.username}</p>
<p>Email from App state: {this.state.email}</p>
<p>Bio from App state: {this.state.bio}</p>
</div>
);
}
}
Child: form.js
class Form extends React.Component {
constructor(props) {
super(props);
this.state = {
...this.props.data
};
}
handleSubmit = e => {
e.preventDefault();
};
handleChange = e => {
this.props.onHandleFormChange({ [e.target.name]: e.target.value });
};
// static getDerivedStateFromProps(nextProps, prevState) {
// console.log(nextProps.data)
// return {
// ...nextProps.data
// };
// }
componentDidUpdate(prevProps) {
if (prevProps.data !== this.props.data) {
this.setState({ ...this.props.data });
}
}
render() {
return (
<div>
<form onSubmit={this.handleSubmit}>
<input
type="text"
name="username"
defaultValue={this.state.username}
onChange={this.handleChange}
/>
<input
type="email"
name="email"
defaultValue={this.state.email}
onChange={this.handleChange}
/>
<textarea
name="bio"
defaultValue={this.state.bio}
onChange={this.handleChange}
/>
<input type="submit" value="submit" />
</form>
</div>
);
}
}
I created an artificial API call by using a setTimeout() in this example and I'm trying to set the state of the parent with the result of the API call. Then I wish to pass that as a prop to the child...
It's working except in the case of a textarea. I can see it if I inspect the DOM but it doesn't actually show in the browser...
Note the "my bio..." in the inspector, but the textarea being empty in the browser.
I've tried componentWillUpdate(), componentDidUpdate() and getDerivedStateFromProps() but nothing seems to work.
What am I missing?
Note: I am not using value="" because then it stops me typing and this form is supposed to allow you to update existing values
Sandbox... https://codesandbox.io/s/ancient-cloud-b5qkp?fontsize=14
It seems to work fine by using the value attribute instead of defaultValue. The defaultValue attribute should really only be used sparingly, since you almost always want your inputs to connect to component state. The optimal way to create a controlled input is by using value.
<textarea
name="bio"
value={this.state.bio}
onChange={this.handleChange}
/>
Change the defaultValue in textarea to value
I have a Login Component and Input Components :
class Login extends React.Component {
constructor(props) {
super(props);
this.handleSubmit = this.handleSubmit.bind(this);
this.handleChangeInput = this.handleChangeInput.bind(this);
this.state = {
email_user: "LOL",
password_user: "",
};
}
handleSubmit(e) {
//alert('A name was submitted: ');
e.preventDefault();
console.log(this.state);
}
handleChangeInput(e){
console.log(e.target.value);
this.setState({value: e.target.value});
}
render() {
return (
<Input size="L" type="email" name="email_user" placeholder="Email" value={this.state.email_user} />
<Input size="L" type="password" name="password_user" placeholder="Mot de passe" value={this.state.password_user} onChange={this.handleChangeInput} /> );
}
}
My Input component returns some HTML like :
<div className={classInput}>
<span className="input__text">
<input type={this.props.type} name={this.props.name} placeholder={this.props.placeholder} defaultValue={this.props.value} onChange={this.handleChange} required />
</span>
</div>
My Input state is updated great by the handleChange inside the Input Component.
But these state are not visible by the Login Component. With or without handleChangeInput, the states in theLogin Component are not saved.
How the Login Component can access to the update state inside child component please?
I am new to React and Redux, hence, sorry for the dummy question.
I have a component:
export default class AddReminder extends Component {
render() {
return (
<div>
Name: <input name="name" />
Description: <input name="description" />
<button>
Add reminder
</button>
</div>
)
}
}
Also, I have an action located in different file what I want to call on button click.
export function addReminder(reminder) { ... }
So, I would like to create a reminder object with name and description properties and call an action. Also, I do not want to create a <form>, just a simple div. Can you please explain how can I do that?
If you don't want to use form element, you can store inputs values in state and on button click, pass state to addReminder func:
export default class AddReminder extends Component {
constructor() {
this.state = {
name: '',
description: ''
}
this.handleSubmit = this.handleSubmit.bind(this);
this.handleNameChange = this.handleNameChange.bind(this);
}
handleNameChange(e) {
this.setState({
name: e.target.value
});
}
handleDescChange(e) {
this.setState({
description: e.target.value
});
}
handleSubmit() {
addReminder(this.state);
}
render() {
return (
<div>
Name: <input name="name" value={this.state.name} onChange={handleNameChange} />
Description: <input name="description" value={this.state.description} onChange={handleDescChange} />
<button onClick={this.handleSubmit}>
Add reminder
</button>
</div>
)
}
}
But this solution is cumbersome, I think.Instead of using state, you can use form element, and inside of onSubmit callback, serialize it values to object and pass them to addReminder func:
// You should install `form-serialize` package from npm first.
import serialize from 'form-serialize';
// Note, we are using functional stateless component instead of class, because we don't need state.
function AddReminder() {
let form;
function handleSubmit(e) {
// Preventing default form behavior.
e.preventDefault();
// serializing form data to object
const data = serialize(form, { hash: true });
addReminder(data);
}
// Assigning form node to form variable
return (
<form ref={node => form = node} onSubmit={handleSubmit}>
Name: <input name="name" />
Description: <input name="description" />
<button type="submit">
Add reminder
</button>
</form>
);
}
class AddReminder extends Component {
constructor(props) {
super(props);
this.handleClick = this.handleClick.bind(this);
}
handleClick(e) {
const parent = e.target.parentNode.children;
const { name, description } = parent;
dispatch(actionName({name.value, description.value}));
}
render() {
return (
<div>
Name: <input name="name" />
Description: <input name="description" />
<button onClick={this.handleClick}>
Add reminder
</button>
</div>
);
}
}
import {addReminder} from './addReminder';
export default class AddReminder extends Component {
render() {
addReminder() {
//call your action or do whatever
return {
name: this.refs.name.value,
description: this.refs.description.value
}
}
return (
<div>
Name: <input name="name" />
Description: <input name="description" />
<button onClick={addReminder.bind(this}>
Add reminder
</button>
</div>
)
}
}