I am trying to implement a triple-state checkbox to react without using ref method.
I found a lot of solutions with ref.
For example:
const { value, checked, indeterminate } = this.props
return render(
<input
type="checkbox"
value={value}
checked={checked}
ref={el => el && (el.indeterminate = indeterminate)}
/>
)
I need a component implementation with ref method
Related
i have an array, called reportsData, then i need to filter it, generating some checkboxes with each of them having a label based on each name that comes from another array (emittersData), so basically i set it like this:
const [searchUser, setSearchUser] = useState<string[]>([])
const mappedAndFiltered = reportsData
.filter((value: any) =>
searchUser.length > 0 ? searchUser.includes(value.user.name) : true
)
Then i render my checkboxes like this:
function EmittersCheckboxes () {
const [checkedState, setCheckedState] = useState(
new Array(emittersData.length).fill(false)
)
const handleOnChange = (position: any, label: any) => {
const updatedCheckedState = checkedState.map((item, index) =>
index === position ? !item : item
)
setSearchUser((prev) =>
prev.some((item) => item === label)
? prev.filter((item) => item !== label)
: [...prev, label]
)
setCheckedState(updatedCheckedState)
};
return (
<div className="App">
{emittersData.map((value: any, index: any) => {
return (
<li key={index}>
<div className="toppings-list-item">
<div className="left-section">
<input
className="h-4 w-4 focus:bg-indigo border-2 border-gray-300 rounded"
type="checkbox"
id={`custom-checkbox-${index}`}
name={value.Attributes[2].Value}
value={value.Attributes[2].Value}
checked={checkedState[index]}
onChange={() => handleOnChange(index, value.Attributes[2].Value)}
/>
<label className="ml-3 font-medium text-sm text-gray-700 dark:text-primary" htmlFor={`custom-checkbox-${index}`}>{value.Attributes[2].Value}</label>
</div>
</div>
</li>
);
})}
</div>
)
}
And on the react component i am rendering each checkbox, that is a li, like:
<ul><EmittersCheckboxes /></ul>
And i render the mappedAndFiltered on the end.
Then it is fine, when i click each generated checkbox, it filters the array setting the state in setSearch user and the array is filtered.
You can check it here: streamable. com /v6bpk6
See that the filter is working, the total number of items in the array is changing based on the checkbox selected (one or more).
But the thing is that each checkbox does not become 'checked', it remains blank (untoggled).
What am i doing wrong, why doesnt it check itself?
You've defined your EmittersCheckboxes component inside another component. and every time that the parent component renders (by state change) your internal component is redefined, again and again causing it to lose it's internal state that React holds for you.
Here's a simplified example:
import React, { useState } from "react";
function CheckboxeComponent() {
const [checkedState, setCheckedState] = useState(false);
return (
<div>
<span>CheckboxeComponent</span>
<input
type="checkbox"
checked={checkedState}
onChange={() => setCheckedState((x) => !x)}
/>
</div>
);
}
export default function App() {
const [counter, setCounter] = useState(1);
function InternalCheckboxeComponent() {
const [checkedState, setCheckedState] = useState(false);
return (
<div>
<span>InternalCheckboxeComponent</span>
<input
type="checkbox"
checked={checkedState}
onChange={() => setCheckedState((x) => !x)}
/>
</div>
);
}
return (
<>
<InternalCheckboxeComponent />
<CheckboxeComponent />
<button onClick={() => setCounter((c) => c + 1)}>{counter}</button>
</>
);
}
There's the App (parent component) with its own state (counter), with a button to change this state, clicking this button will increase the counter, causing a re-render of App. This re-render redefines a new Component named InternalCheckboxeComponent every render.
The InternalCheckboxeComponent also has an internal state (checkedState).
And there's an externally defined functional component named CheckboxeComponent, with this component React is able to hold its own state, because it's not redefined (It's the same function)
If you set the state of each to be "checked" and click the button, this will cause a re-render of App, this will redefine the InternalCheckboxeComponent function, causing React to lose its state. and the CheckboxeComponent state remains in React as it's the same function.
How do I make material UI component property to carry the value of some other property of same component?
Here I want value property to refer checked property.
want to do something like this
<Switch
checked={singleHeading.required}
onChange={onHandleChangeCheck}
name="required"
value={event.target.checked}
/>
Using hooks you can perform that with this:
render() {
const [checked, setChecked] = useState(singleHeading.required);
const handleSwitchCheck = event => {
setChecked(event.target.checked);
onHandleChangeCheck(event);
};
// ... whatever code you have
<Switch
checked={checked}
onChange={handleSwitchCheck}
name="required"
value={checked}
/>
// ... whatever code you have
}
I'm trying to connect material-ui ToggleButtonGroup with redux form and getting issues with this.
Here is my code:
<Field
name='operator'
component={FormToggleButtonGroup}
>
<ToggleButton value='equals'>Equal</ToggleButton>
<ToggleButton value='not_equals'>Not equal</ToggleButton>
</Field>
.. and my component, passed to Field:
const FormToggleButtonGroup = (props) => {
const {
input,
meta,
children
} = props;
return (
<ToggleButtonGroup
{...input}
touched={meta.touched.toString()}
>
{children}
</ToggleButtonGroup>
);
};
export default FormToggleButtonGroup;
the problem is, when I select value (toggle option), selected value is not passed to redux store, it passed only after loosing focus and then throws error 'newValue.splice is not a function'
Please help to deal with this issue
Sandbox with sample code
Playing with the component I finally found the solution.
I need manually assign new value got from ToggleButtonGroup component and put this value to redux store. Here is how working code looks:
const FormToggleButtonGroup = (props) => {
const {
input,
meta,
children,
...custom
} = props;
const { value, onChange } = input;
return (
<ToggleButtonGroup
{...custom}
value={value}
onChange={(_, newValue) => {
onChange(newValue);
}}
touched={meta.touched.toString()}
>
{children}
</ToggleButtonGroup>
);
};
Main change is getting redux's function onChange and call it with new value, selected when value toggled. There is onChange related to ToggleButtonGroup component and another onChange related to Redux. You need to call latter when ToggleButtonGroup's onChange occurs.
I want to access a nested component from parent component.
This is Bill Form.jsx
import BillDetailForm from './BillDetailForm';
render(){
return (
<form onSubmit={handleSubmit}>
<FieldArray
name= 'detail'
component={BillDetailForm}
placeholder= '...detail'
label='Detail'
/>
</form>
);
}
}
BillForm is the parent component.
This is a nested component or child component of BillForm: BillDetailForm.jsx
render(){
return(
<form onSubmit={ handleSubmit }>
<div>Detail:</div>
<FieldArray
name= 'detail'
component={RenderDetail}
label='Detail'
/>
</form>
)
}
Inside BillDetailForm is RenderDetail:
const RenderDetail = ({fields, meta: { error,submitFailed}},props) => (
<dl>
<dt>
<button type="button" className= 'btn btn-primary' onClick={() => fields.push()}>Add
Detail</button>
{submitFailed && error && <span>{error}</span>}
</dt>
{ fields.map((registerDetail, index) =>
//In the following line renderDetail is accesing Detail component.
<Detail detailItem={registerDetail} fields={fields} index={index} key={index}/>
)
}
{error && <dt className="error">{error}</dt>}
</dl>
);
This is Detail Class Component:
class Detail extends Component{
render(){
const{detailItem,index,fields,isSubtotal} = this.props;
return(
<dd key={index}>
<br></br>
<button className= 'btn btn-light mr-2'
type="button"
title="Remove detail"
onClick={() => { fields.remove(index)
if(fields.length == 0 || fields.length === undefined){
}
try{
for(let x in fields){
fields.remove(index)
let d = fields.selectedIndex;
if(fields.remove(index) && d >= 1 && d< fields.length ){
fields.removeAll(index);
}
}
}catch{console.info("deletes non numerical index")}
}}> Delete </button>
<h4>DetailRegister #{index + 1}</h4>
<Field
id={`${detailItem}._id`}
name={`${detailItem}.quantity`}
component= {NumberPickerInteger}
placeholder= '...quantity'
label = "Quantity"
/>
<br></br>
<h3><b>Product</b></h3>
<Field
id={`${detailItem}._id`}
name={`${detailItem}.product.code`}
type="number"
component= {RenderFieldNumeric}
placeholder='...Product's code'
label = "Product's code"
/>
<Field
id={`${detailItem}._id`}
name={`${detailItem}.product.name`}
type="text"
component= {RenderField}
placeholder='...Product's name'
label = "Product's name"
/>
<Field
id={`${detailItem}._id`}
name={`${detailItem}.product.price`}
component= {NumberPickerr}
placeholder= '...Price'
label = "Product's price"
/>
<br></br>
<h3><b>Subtotal</b></h3>
<Field
id={`${detailItem}._id`}
name={`${detailItem}.subtotal`}
component= {SubtotalWidget}
placeholder= '...subtotal'
label = "Subtotal"
>
{isSubtotal}
</Field>
</dd>
);
}
}
I want to access e.g ${props.detailItem}.subtotal that is in Detail from BillForm. BillForm accesses to BillDetailForm, BillDetailForm accesses to renderDetail, and last renderDetail acceses to Detail.
The question is: How can I access and use props like quantity and subtotal with dynamic index (props.index) from BillForm? I want to access Detail component from BillForm, respecting the following secuence in order access: BillForm -> BillDetailForm -> RenderDetail -> Detail
If I understand correctly what you are saying, it seems you are going against the ethos of React. If your parent component wants access to a piece of data, then that data should start in the parent and be passed down. This way, if the data changes it will call a re-render of components and update all necessary components.
Some other advice. Try not o have so much logic inside your component handlers, it looks messy and will run every render cycle. Abstract this into a method on the class and call it when required.
My example will hopefully help you with your issue, but I recommend having a read of the React documentation as it is very good with simple examples.
The use of class will be deprecated eventually in favour of function components and the Hooks API.
class ParentComponent {
state = {
value: 0,
}
methodToDoSomething = (passedVal) => {
this.setState({
value: passVal,
});
}
render() {
const myState = this.state;
return (
<Component {...myState} />
)
}
}
class Component {
state = {}
render() {
const { value , methodToDoSomething } = this.props;
return (
<div onClick={methodToDoSomething}>
{value}
</div>
)
}
}
// Hooks API
const ParentComponent = () => {
const [stateVal, updateState] = React.useState('myString');
return (
<div>
{stateVal}
<Component passedVal={stateVal} passedHandler={updateState} />
</div>
)
}
const Component = ({ stateVal, passedHandler }) => {
function updateMyValue() {
passedHandler('menewvalue');
}
return (
<div onClick={updateMyValue}>
{stateValue}
<div/>
)
}
To avoid passing lots down all the children components, I would recommend reading up on the Context Hook.
*** UPDATE ***
The above example is rudimentary and tries to answer the question presented, there are always many ways to solve a problem.
Passing props can be messy and a maintenance overhead. Most larger applications will benefit from using a state library to manage their global state. The Context API is a good tool to use to wrap a cohesive set of components so they can share data/props without prop-drilling (passing props down many child components).
Custom hooks are another good way to share data. Create a hook containing your data and any other methods for the task and use this hook inside parent and child components to share said data.
How do I select certain bars in react.js?
This is my code:
var Progressbar = React.createClass({
getInitialState: function () {
return { completed: this.props.completed };
},
addPrecent: function (value) {
this.props.completed += value;
this.setState({ completed: this.props.completed });
},
render: function () {
var completed = this.props.completed;
if (completed < 0) { completed = 0 };
return (...);
}
I want to use this React component:
var App = React.createClass({
getInitialState: function () {
return { baction: 'Progress1' };
},
handleChange: function (e) {
var value = e.target.value;
console.log(value);
this.setState({ baction: value });
},
handleClick10: function (e) {
console.log('You clicked: ', this.state.baction);
document.getElementById(this.state.baction).addPrecent(10);
},
render: function () {
return (
<div class="center">Progress Bars Demo
<Progressbar completed={25} id="Progress1" />
<h2 class="center"></h2>
<Progressbar completed={50} id="Progress2" />
<h2 class="center"></h2>
<Progressbar completed={75} id="Progress3" />
<h2 class="center"></h2>
<span>
<select name='selectbar' id='selectbar' value={this.state.baction} onChange={this.handleChange}>
<option value="Progress1">#Progress1</option>
<option value="Progress2">#Progress2</option>
<option value="Progress3">#Progress3</option>
</select>
<input type="button" onClick={this.handleClick10} value="+10" />
<button>+25</button>
<button>-10</button>
<button>-25</button>
</span>
</div>
)
}
});
I want to execute the handleClick10 function and perform the operation for my selected progressbar.
But the result I get is:
You clicked: Progress1
TypeError: document.getElementById(...) is null
How do I select the certain Element in react.js?
You can do that by specifying the ref
EDIT: In react v16.8.0 with function component, you can define a ref with useRef. Note that when you specify a ref on a function component, you need to use React.forwardRef on it to forward the ref to the DOM element of use useImperativeHandle to to expose certain functions from within the function component
Ex:
const Child1 = React.forwardRef((props, ref) => {
return <div ref={ref}>Child1</div>
});
const Child2 = React.forwardRef((props, ref) => {
const handleClick= () =>{};
useImperativeHandle(ref,() => ({
handleClick
}))
return <div>Child2</div>
});
const App = () => {
const child1 = useRef(null);
const child2 = useRef(null);
return (
<>
<Child1 ref={child1} />
<Child1 ref={child1} />
</>
)
}
EDIT:
In React 16.3+, use React.createRef() to create your ref:
class MyComponent extends React.Component {
constructor(props) {
super(props);
this.myRef = React.createRef();
}
render() {
return <div ref={this.myRef} />;
}
}
In order to access the element, use:
const node = this.myRef.current;
DOC for using React.createRef()
EDIT
However facebook advises against it because string refs have some issues, are considered legacy, and are likely to be removed in one of the future releases.
From the docs:
Legacy API: String Refs
If you worked with React before, you might be
familiar with an older API where the ref attribute is a string, like
"textInput", and the DOM node is accessed as this.refs.textInput. We
advise against it because string refs have some issues, are considered
legacy, and are likely to be removed in one of the future releases. If
you're currently using this.refs.textInput to access refs, we
recommend the callback pattern instead.
A recommended way for React 16.2 and earlier is to use the callback pattern:
<Progressbar completed={25} id="Progress1" ref={(input) => {this.Progress[0] = input }}/>
<h2 class="center"></h2>
<Progressbar completed={50} id="Progress2" ref={(input) => {this.Progress[1] = input }}/>
<h2 class="center"></h2>
<Progressbar completed={75} id="Progress3" ref={(input) => {this.Progress[2] = input }}/>
DOC for using callback
Even older versions of react defined refs using string like below
<Progressbar completed={25} id="Progress1" ref="Progress1"/>
<h2 class="center"></h2>
<Progressbar completed={50} id="Progress2" ref="Progress2"/>
<h2 class="center"></h2>
<Progressbar completed={75} id="Progress3" ref="Progress3"/>
In order to get the element just do
var object = this.refs.Progress1;
Remember to use this inside an arrow function block like:
print = () => {
var object = this.refs.Progress1;
}
and so on...
For getting the element in react you need to use ref and inside the function you can use the ReactDOM.findDOMNode method.
But what I like to do more is to call the ref right inside the event
<input type="text" ref={ref => this.myTextInput = ref} />
This is some good link to help you figure out.
With newer versions of React you can use and manipulate the DOM via hooks like this:
import React, { useEffect, useRef } from "react";
const MyComponent = () => {
const myContainer = useRef(null);
useEffect(() => {
console.log("myContainer..", myContainer.current);
});
return (
<>
<h1>Ref with react</h1>
<div ref={myContainer}>I can use the DOM with react ref</div>
</>
);
};
export default MyComponent;
Whenever you want to access your DOM element just use myContainer.current
You can replace
document.getElementById(this.state.baction).addPrecent(10);
with
this.refs[this.state.baction].addPrecent(10);
<Progressbar completed={25} ref="Progress1" id="Progress1"/>
Disclaimer: While the top answer is probably a better solution, as a beginner it's a lot to take in when all you want is something very simple. This is intended as a more direct answer to your original question "How can I select certain elements in React"
I think the confusion in your question is because you have React components which you are being passed the id "Progress1", "Progress2" etc. I believe this is not setting the html attribute 'id', but the React component property. e.g.
class ProgressBar extends React.Component {
constructor(props) {
super(props)
this.state = {
id: this.props.id <--- ID set from <ProgressBar id="Progress1"/>
}
}
}
As mentioned in some of the answers above you absolutely can use document.querySelector inside of your React app, but you have to be clear that it is selecting the html output of your components' render methods. So assuming your render output looks like this:
render () {
const id = this.state.id
return (<div id={"progress-bar-" + id}></div>)
}
Then you can elsewhere do a normal javascript querySelector call like this:
let element = document.querySelector('#progress-bar-Progress1')
You have to follow two different ways to do it in Class and Functional components.
For class components
<input type="text" ref={ref => this.myTextInput = ref} />
Look at the above code. Use "ref" attribute to refer to the relevant element. Then you will be able to refer to that element using that reference. In this example, I can use "this.myTextInput" to refer to the above input element.
For functional components
const textInput = useRef(null)
Use the "useRef" hook and set that variable name as the value of the "ref" attribute of the element you want to refer to (like below).
<input type="text" ref={textInput} />
An example for this on functional components.
import React, {useRef} from 'react'
function CustomTextInput(props) {
// textInput must be declared here so the ref can refer to it
const textInput = useRef(null);
function handleClick() {
textInput.current.focus();
}
return (
<div>
<input type="text" ref={textInput} />
</div>
);
}
Want to learn more? Here you go
Since React uses JSX code to create an HTML we cannot refer dom using regulation methods like documment.querySelector or getElementById.
Instead we can use React ref system to access and manipulate Dom as shown in below example:
constructor(props){
super(props);
this.imageRef = React.createRef(); // create react ref
}
componentDidMount(){
**console.log(this.imageRef)** // acessing the attributes of img tag when dom loads
}
render = (props) => {
const {urls,description} = this.props.image;
return (
<img
**ref = {this.imageRef} // assign the ref of img tag here**
src = {urls.regular}
alt = {description}
/>
);
}
}
In my case, I wasn't able to use ref because elements were somewhere between many child components and I have to access them by class and id instead of ref. So, trying with useEffect hook didn't work as it can't find the element:
useEffect(() => {
const el1 = document.querySelector('.el1')
const el2 = document.querySelector('.el2')
}, [])
The element is undefined because when it is mounted the children components also doesn't mounted before this parent component.
So, what I did is to use timeout:
useEffect(() => {
const timer = setTimeout(() => {
const el1 = document.querySelector('.el1')
const el2 = document.querySelector('.el2')
},500)
return () => {
clearTimeout(timer)
}
}, [])
Now, it worked fine. It found the DOM and I was able to manipulate with them. Hope, this helps someone!
The equivalent of document.getElementById() in React is document.querySelector().