I am trying to write a delete method in order to delete an element from a list, first of all I am not being able to write it in a setState function so I have it as a direct function call, How can I manage to signal a re-render after the direct function or manage to place the function in the setState method for automatic re-render?
class TASKMANAGER extends Component {
constructor(props){
super(props);
this.state= {
name: "",
description:"",
priority: "urgent",
tasklist: [],
}
this.handleTitleChange= this.handleTitleChange.bind(this);
//this.handleDescriptionChange= this.handleDescriptionChange.bind(this);
//this.handlePriorityChange= this.handleDescriptionChange.bind(this);
this.handleClick= this.handleClick.bind(this);
}
handleTitleChange = event => {
this.setState( {
name: event.target.value
})
};
handleDescriptionChange = event => {
this.setState({
description: event.target.value
})
};
handlePriorityChange = event => {
this.setState({
priority: event.target.value
})
};
handleClick = event => {
this.setState((state) => {
const tasklist = [
...state.tasklist,
[
state.name,
state.description,
state.priority
]
];
return {
tasklist
};
});
//console.log(this.state.tasklist);
};
handleDelete = index => {
this.setState(() => {
this.state.tasklist.splice(index, 1)
});
console.log(this.state.tasklist)
} THIS ONE IS THE FUNCTION I CANNOT SET TO WORK TO TRIGGER THE AUTO RE-RENDER
render() {
const task_item = this.state.tasklist.map((arr, index) => (
<li
key= {index}
className= 'task'>
Task: {arr[0]} <br />
Description: {arr[1]} <br />
Priority: {arr[2]} <br />
<div className='delete-button' onClick={
/*() => {this.state.tasklist.splice(index, 1);}*/ THIS ONE IS THE DIRECT FUNCTION THAT WORKS, BUT DOESN'T TRIGGER THE RE-RENDER, IT SHOWS WHEN I TYPE AGAIN ON THE INPUTS
this.handleDelete
}>delete</div>
</li>
))
return (
<div>
<div className= 'task-form'>
<form>
<div>
<label>Name your task!</label>
<input type= 'text' id='task-title' value={this.state.name} onChange={this.handleTitleChange} />
</div>
<div>
<label>Description?</label>
<textarea id='description' value={this.state.description} onChange={this.handleDescriptionChange}/>
</div>
<div>
<label>Priority?</label>
<select value={this.state.priority} onChange={this.handlePriorityChange}>
<option value='urgent'>Urgent</option>
<option value='regular'>Regular</option>
<option value='Can wait'>Can wait</option>
</select>
</div>
</form>
<button onClick={this.handleClick}>PRESS</button>
</div>
<div className='list-items'>
<ul className='list-render'>
{task_item}
</ul>
</div>
</div>
)
}}
export default TASKMANAGER
You shouldn't be making any mutations to the current state, but instead build a new state from the existing state, generating a new, filtered array along the way
handleDelete = index => {
this.setState((state) => ({
...state,
tasklist: state.taskList.filter((_,i) => i != index)
}));
}
When you map your taskList to JSX below, you will need to avoid using the index of the item as key, because the optimizations react makes using the key value will be operating under broken assumptions. Use a key value that remains constant and unique per item. Perhaps its name, or an identifier that is attached to it when created.
There is no need to assign the list. Just splice it. Use something like this to change the state:
delete={()=>{this.setState({phase:1-this.state.phase});
this.state.list.splice(index,1)}}
Related
I have RecipeCreate component, and inside of that I want a user to be able to render as many IngredientDetailsInput components as needed to complete the recipe.
I do this by creating an empty object in an ingredients array within RecipeCreate, and then iterate over this array of empty objects, generating a corresponding IngredientDetailsInput for each empty object.
From within IngredientDetailsInput I want to update the empty corresponding empty object in RecipeCreate with data passed up from IngredientDetailsInput. Since IngredientDetailsInput has the index of where it's object lives in the ingredients array in it's parent component, I believe this is possible.
Here is working sandbox that demonstrates the issue
I'm close, but each time the handleChange runs it is creating a new object in the ingredients array and I'm not sure why, or what other options to use besides handleChange - I'd like there not to have to be a form submit if possiblee
And here is code for both components
import React, { useState } from "react";
const RecipeCreate = (props) => {
const [ingredients, setIngredients] = useState([]);
const [recipeTitle, setRecipeTitle] = useState("");
//if an ingredient object has been added to the ingredients array
//render an IngredientDetailsInput component, passing along the index position
//so we can update it later
const renderIngredientComponents = () => {
if (ingredients) {
return ingredients.map((_, index) => {
return (
<IngredientDetailsInput
key={index}
position={index}
updateIngredientArray={updateIngredientArray}
/>
);
});
}
};
//broken function that should find the object position in ingredients
//and copy it, and non-mutated ingredient objects to a new object, and set the state to this
//new object
const updateIngredientArray = (key, value, position) => {
return setIngredients((prevIngredients) => {
console.log(ingredients)
return [...prevIngredients, prevIngredients[position][key] = value]
});
};
//allows the user to add another "ingredient", rendering a new IngredientDetailsInput component
//does so by adding a new, empty object to the ingredients array
const addElementToArray = () => {
setIngredients((prevIngredients) => [...prevIngredients, {}]);
};
return (
<div>
<div>
<form>
<div>
<label>Recipe Title</label>
<input
type="text"
name="recipeTitle"
value={recipeTitle}
onChange={(e) => setRecipeTitle(e.target.value)}
/>
</div>
<div>
<p>Ingredients</p>
{renderIngredientComponents()}
<div>
<p onClick={() => addElementToArray()}>+ ingredient</p>
</div>
</div>
<div></div>
<button type="submit">Submit</button>
</form>
</div>
</div>
);
};
export default RecipeCreate;
//child component that should allow changes to bubble up to RecipeCreate
export function IngredientDetailsInput(props) {
return (
<div>
<input
type="number"
name="measurement"
id="measurement"
placeholder="1.25"
onChange={(e) =>
props.updateIngredientArray(
"measurement",
e.target.value,
props.position
)
}
/>
<div>
<label htmlFor="measurementType">type</label>
<select
id="unitType"
name="unitType"
onChange={(e) =>
props.updateIngredientArray(
"unitType",
e.target.value,
props.position
)
}
>
<option>tbsp</option>
<option>cup</option>
<option>tspn</option>
<option>pinch</option>
<option>ml</option>
<option>g</option>
<option>whole</option>
</select>
</div>
<input
type="text"
name="ingredientName"
id="ingredientName"
placeholder="ingredient name"
onChange={(e) =>
props.updateIngredientArray(
"ingredientName",
e.target.value,
props.position
)
}
/>
</div>
);
}
The assignment prevIngredients[position][key] = value returns value instead of prevIngredients[position][key]. Thus when you setting the state, it returns the previous stored ingredients as well as that value.
const updateIngredientArray = (key, value, position) => {
return setIngredients((prevIngredients) => {
console.log(ingredients)
return [...prevIngredients, prevIngredients[position][key] = value]
});
};
A quick fix would be to recopy a new array of the current ingredient, then changing the position and key that you want.
const updateIngredientArray = (key, value, position) => {
const tmp = ingredients.map((l) => Object.assign({}, l));
tmp[position][key] = value;
setIngredients(tmp);
};
May be you can try like this?
const {useState} = React;
const App = () => {
const [state, setState] = useState([
{
name: "",
amount: "",
type: ""
}
]);
const addMore = () => {
setState([
...state,
{
name: "",
amount: "",
type: ""
}
]);
};
return (
<div className="App">
<h1>Recipe</h1>
<h2>Start editing to see some magic happen!</h2>
<label>Recipe Title</label>
<input type="text" />
<br /> <br />
<div onClick={addMore}>Add More +</div>
{state && state.map((val, ikey) =>
<div>
<br />
<label>Ingredients</label>
<input type="text" placeholder="Name" />
<input type="text" placeholder="Amount" />
<select>
<option>tbsp</option>
<option>cup</option>
<option>tspn</option>
<option>pinch</option>
<option>ml</option>
<option>g</option>
<option>whole</option>
</select>
</div>
)}
</div>
);
}
ReactDOM.render(
<App />,
document.getElementById("react")
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.1/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.1/umd/react-dom.production.min.js"></script>
<div id="react"></div>
I want to push the tip which I'm calculating in #this.calculate onto tip_arr[]. In that I'm not able to access my first item of as it is showing ["",item,item]. Here my first item is getting empty just the string. Here I'm calculating per person tip how much he is paying and after that diplay that.
export default class Calculation extends React.Component {
constructor(props) {
super(props)
this.state = {
amount: '',
tip_per: '',
name: '',
tip: '',
name_arr:[],
tip_arr:[]
}
this.handle = (event) => {
this.setState({ tip_per: event.target.value });
}
this.calculate = () => {
this.setState({ tip: ((this.state.amount) * this.state.tip_per) / 100 })
this.name_change()
this.tip_change()
}
this.name_change=()=>{
let{name_arr,name}=this.state
name_arr.push(name)
}
this.tip_change=()=>{
let{tip_arr,tip}=this.state
tip_arr.push(tip)
}
}
render(){
return(
<>
<div className='Header'>
<header>Tip Calculator<br />Build in React</header>
</div>
<div className='Input'>
<h4>Enter the Bill Amount:-</h4>
<input type='number' className='width' value={this.state.amount}
onChange={(e) => this.setState({ amount: e.target.value })}></input>
<hr />
<div className='inner'>
<p>How was the Service:- <span>
<select onChange={this.handle}>
<option>Choose...</option>
<option value={20}>Excellent:- 20%</option>
<option value={10}>Moderate:- 10%</option>
<option value={5}>Bad:- 5%</option>
</select>
<input type='text' className='filed' placeholder="Customer Name"
value={this.state.name} onChange={(e) => this.setState({ name: e.target.value })} />
<button type='button' className='filed else' onClick={this.calculate}>Add Customer</button>
</span></p>
</div>
</div>
<div className='Output'>
<p>Customer List:-</p><hr />
<ul className='UL'>
{this.state.name_arr.map((item,index)=>{
return <li key={index}>{item} offering a tip of</li>})}
<span> <ul className='UL'>
{this.state.tip_arr.map((item,index)=>{
return <li key={index}>{item} rupees </li>})}
</ul>
</span>
</ul>
{console.log(this.state.name_arr)}
{console.log(this.state.tip_arr)}
</div>
</>
)
}
};
You're attempting to mutate a state variable. You have to update the value via setState. You should also pass setState a function instead of a plain object in this case so that you can access the correct value since state updates are asynchronous.
tip_change = () => {
this.setState((prevState) => {
const { tip, tip_arr } = prevState;
return {
tip_arr: [...tip_arr, tip]
};
});
}
You can't change state directly.
Do Not Modify State Directly.
Read how to use state correctly from React documentation
To update it, you need to call this.setState eg:
this.tip_change=()=>{
let{tip_arr,tip}=this.state
this.setState(prevState => {
let newTipArray = [prevState.tip_arr, tip]
return {tip_arr: newTipArray }
})
}
This should also be the case for name_arr state. eg:
this.name_change=()=>{
let{name_arr,name}=this.state
//name_arr.push(name) // can't manipulate state directly.
this.setState(prevState => {
let newNameArr = [prevState.name_arr, name]
return {name_arr: newTipArray }
})
}
Update: as #Phishy, using second form of setState() that accepts a function rather than an object helps fix some of state quirks because of the asyncronous nature of React state.
Here is a nice article that explains why to Beware: React setState is asynchronous!
I am pretty new to the wonderful world of React.
I have two inputs passing data through from an API that renders a list of options. And I want to send the selected inputs from those options back to the parent in the input fields to display for another search.
I have tried passing state down to them and render them them optionally with both a ternary and an if else statement in the "SearchCityList" component in several ways but I either get both lists rendered and they would have to choose between one list that is doubled to put in each input field or it only puts the selected value in one input. Would appreciate any & all suggestions Thanks!
class Form extends Component {
state = {
showComponent: false,
showComponent2: false,
};
// open/close control over SearchCity component box
openSearch = () => {
this.setState({ showComponent: true });
};
openSearch2 = () => {
this.setState({ showComponent2: true });
};
closeSearch = () => {
this.setState({
showComponent: false,
showComponent2: false
});
};
// Passed down cb function to get selected city search in selectCity component
GoingTo = (flights) => {
this.setState({ GoingTo: [flights] });
};
LeavingFrom = (flights) => {
this.setState({ LeavingFrom: [flights] });
};
render() {
return (
<div>
<form className="form-fields container">
<div className="inputs">
<h1>Search for a flight!</h1>
<div className="depart">
<input
onClick={this.openSearch}
className="flight-search"
placeholder="Leaving From"
value={this.state.LeavingFrom}
></input>
<input type="date"></input>
</div>
<div className="Returning">
<input
onClick={this.openSearch2}
className="flight-search"
placeholder="Going To "
value={this.state.GoingTo}
></input>
<input type="date" placeholder="Returning"></input>
</div>
</div>
<button>Check Flights!</button>
</form>
{this.state.showComponent || this.state.showComponent2 ? (
<SearchCity
openSearch={this.openSearch}
openSearch2={this.openSearch2}
flightSearch={this.state.flightSearch}
closeSearch={this.closeSearch}
GoingTo={this.GoingTo}
LeavingFrom={this.LeavingFrom}
onSearchSubmission={this.onSearchSubmission}
closeSearch={this.closeSearch}
/>
) : null}
</div>
);
}
}
export default Form;
class SearchCity extends Component {
state = {
LeavingFrom: "",
GoingTo: "",
search: "",
flightSearch: [],
};
// Search submission / api call
onSearchSubmission = async (search) => {
const response = await Axios.get(
{
headers: {
"
useQueryString: true,
},
}
);
// set New state with array of searched flight data sent to searchCity component
const flightSearch = this.setState({ flightSearch: response.data.Places });
};
// Callback function to send search/input to parent "Form" component
submitSearch = (e) => {
e.preventDefault();
this.onSearchSubmission(this.state.search);
};
// closeSearch callback function sent from Form component to close pop up search box when X is pressed
closeSearch = () => {
this.props.closeSearch();
};
render() {
return (
<div className="container search-list">
<form onChange={this.submitSearch}>
<i className="fas fa-times close-btn" onClick={this.closeSearch}></i>
<input
onChange={(e) => this.setState({ search: e.target.value })} //query-search api
value={this.state.search}
className="search-input"
type="text"
placeholder="Search Locations"
></input>
<div className="search-scroll">
<SearchCityList
openSearch={this.props.openSearch}
openSearch2={this.props.openSearch2}
LeavingFrom={this.props.LeavingFrom}
GoingTo={this.props.GoingTo}
flightSearch={this.state.flightSearch}
/>
</div>
</form>
</div>
);
}
}
export default SearchCity;
function SearchCityList({ flightSearch, LeavingFrom, GoingTo }) {
const renderList = flightSearch.map((flights) => {
return (
<div>
<SelectCityLeaving LeavingFrom={LeavingFrom} flights={flights} />
<SelectCityGoing GoingTo={GoingTo} flights={flights} />
</div>
);
});
return <div>{renderList}</div>;
}
export default SearchCityList;
First of all, when dealing with state, make sure you initialize in the constructor and also ensure you bind your handlers to this component instance as this will refer to something else in the handlers if you don't and you won't be able to call this.setState().
constructor(props) {
super(props); // important
state = {
// your state
};
// make sure to bind the handlers so `this` refers to the
// component like so
this.openSearch = this.openSearch.bind(this);
}
A working example of my problem can be found at:
https://codepen.io/RyanCRickert/pen/vYYQeaW
I am prop drilling a function two levels and passing that function along with an index to a rendered component. When a name is submitted it renders a new component which shows the name and div which has an onClick (X). I am trying to receive the index of where the name is located in the array which it lives so that I may splice it out when the button is clicked.
If I enter the name "Bob" for example, then click the div with the listener I can console log the event.target. Using the above example I get "<div class='person-item__X' value='0'>X</div>" for event.target and undefined for event.target.value. The value is being assigned as <div onClick={props.removeName} class="person-item__X" value={props.value}>X</div>.
Am I just unable to grab the value of a div in such a manor? Or is there something that I am missing? Thank you
Change these to your code
const PersonListItem = props => (
<div class="person-item">
<div class="person-item__name">{props.name}</div>
<div onClick={() => props.removeName(props.value)} class="person-item__X" value={props.value}>X</div>
</div>
);
Inside PeopleList replace this line
<PersonListItem key={index} name={person} value={index} removeName={(id) => props.removeName(id)} />
Inside TeamGenerator replace this line
<PeopleList people={this.state.names} removeName={(id) => this.handleRemoveName(id)} />
now in handleRemoveName you will recieve a id of the item on which X was clicked
handleRemoveName = id => {
const currentArr = this.state.names;
console.log(id);
}
In your case, to grab the value inside this div, you should use ref API.
Your code should look like this:
TeamGenerator.js
import React, { Component } from "react";
import CustomModal from "./Modal";
import PeopleList from "./PeopleList";
import "./index.css";
export default class App extends Component {
constructor(props) {
super(props);
// Create a ref
this.divTextRef = React.createRef();
this.state = {
names: [],
selectedName: ""
};
}
handleCloseModal = () => {
this.setState({
selectedName: ""
});
};
handleChange = e => {
this.setState({ name: e.target.value });
};
handleRemoveName = index => {
// Get your name and index this way
console.log("Your text: ", this.divTextRef.current.innerHTML);
console.log("Your index: ", index);
};
handleSubmit = e => {
e.preventDefault();
const currentNames = this.state.names;
if (this.state.name)
currentNames.push(
this.state.name[0].toUpperCase() + this.state.name.slice(1)
);
this.setState({
name: "",
names: currentNames
});
};
render() {
return (
<div className="container">
<CustomModal
selectedName={this.state.selectedName}
closeModal={this.handleCloseModal}
/>
<form onSubmit={this.handleSubmit}>
<label>
Add name:
<input
type="text"
value={this.state.name}
onChange={this.handleChange}
/>
</label>
<input type="submit" value="Submit" />
</form>
<div className="people-list-container">
<PeopleList
people={this.state.names}
removeName={this.handleRemoveName}
upperRef={this.divTextRef} // Pass the ref down from your Component tree
/>
</div>
</div>
);
}
}
PeopleList.js
import React from "react";
import PersonListItem from "./PersonListItem";
export default class PeopleList extends React.Component {
render() {
return (
<div className="people-container">
<div className="people-title">List of people</div>
<div className="people-list">
{this.props.people.length === 0 ? (
<div className="people-item">
<span>No people added</span>
</div>
) : (
this.props.people.map((person, index) => (
<PersonListItem
key={index}
name={person}
value={index}
removeName={() => this.props.removeName(index)} // Passing index to the removeName function of Parent
upperRef={this.props.upperRef} // Continue passing it down to PersonListItem
/>
))
)}
</div>
</div>
);
}
}
PersonListItem.js
import React from "react";
const PersonListItem = props => (
<div className="person-item">
<div ref={props.upperRef} className="person-item__name"> // Use the passed ref
{props.name}
</div>
<div
onClick={props.removeName}
className="person-item__X"
value={props.value}
>
X
</div>
</div>
);
export default PersonListItem;
The div node does not have the value like input, so you can not grab it by your old way.
import reqwest from './public/reqwest.js'
const PAGE_SIZE = 10
class App extends Component {
constructor() {
super()
this.state = {
page: 1,
arr: []
}
}
singleInfo(page) {
reqwest({
url: 'https://cnodejs.org/api/v1/topics',
data: {
limit: PAGE_SIZE,
page: this.state.page
},
success: function (data) {
this.setState({
arr: data.data
})
}.bind(this)
})
}
changeState(newState) {
this.setState(newState)
this.singleInfo(newState.page)
}
render() {
return (
<div>
<Menu val={this.state.page} changeParentState={(state) => this.changeState(state)} />
<List arr={this.state.arr} />
</div>
);
}
}
class Menu extends Component {
handleChange(event) {
if(event.target.value) {
this.props.changeParentState({
page: event.target.value
})
}
}
render() {
console.log(this)
return <input type="text" defaultValue={this.props.val} onChange={(event) => this.handleChange(event)} />
}
}
class List extends Component {
render() {
return <ul>
{
this.props.arr.map((ele) => {
return (
<li key={ ele.id }>
<p className="title">{ ele.title }</p>
<p className="date">{ ele.create_at }</p>
<p className="author">{ ele.author.loginname }</p>
</li>
)
})
}
</ul>
}
}
I can't get the current value of the input by onChange in Menu module.
In my code, the App has two child components - List & Menu.
You can input the page in Menu component, so it will send Ajax() to get the info of the page. But the truth is: After I change the value of input like 1 -> 10, the ajax get the value of 1.
Before this, I know the difference between keyup or keydown and keypress. They have the difference cross browser. But I just want get the current value of the input By React.js.
First, change:
<input type="text" defaultValue={this.props.val} onChange={(event) => this.handleChange(event)} />
To:
<input type="text" value={this.props.val} onChange={(event) => this.handleChange(event)} />
so that your input will update to the correct value on re-render.
Second, remember that setState is often asynchronous. So do not expect the state to be changed right after calling setState.
Your changeState method is good in this respect since it passes newState to singlePageRequest. However singlePageRequest does not use the supplied value and instead uses this.state.page. Change it to use the supplied value and you should be OK:
singleInfo(page) {
reqwest({
url: 'https://cnodejs.org/api/v1/topics',
data: {
limit: PAGE_SIZE,
page: page
},
success: function (data) {
this.setState({
arr: data.data
})
}.bind(this)
})
}