[英]Component only updates after two clicks React
我正在構建一個React應用程序,除其他功能外,該應用程序會在單擊按鈕時生成一個隨機數,然后將JSON對象數組過濾為該隨機數索引處的一個(即JSON [random])。 通常,應該在過濾了JSON對象數組之后重新渲染該應用程序,但是由於某些原因,第一次單擊該按鈕並選擇一個隨機變量時,需要兩次單擊才能更新。 從那時起,它會按預期進行更新,每次單擊按鈕時都會使用新的隨機渲染。
我不確定問題是來自App.js還是更低的地方。 第一次單擊時,它會生成一個新的隨機數,並且可以將其保存為狀態,但無法立即重新渲染。 在隨后的點擊中,事情似乎是根據先前生成的隨機數進行更新的,而新的隨機數則被放入隊列中。 我希望所有這些都可以一次性完成:單擊,生成隨機,保存到狀態,更新以反映新的隨機JSON [random]。
這可能與我實現生命周期方法的方式有關,因為我承認我不確定每種方法的所有細微差別,並且只是嘗試使用任何一種似乎可以滿足我要求的方法。 如果您有任何建議,請告訴我...
謝謝!
以下是相關文件:
App.js-在Header.state.randomClicks中注冊新點擊時生成並存儲隨機數的地方
class App extends Component {
constructor(props){
super(props)
this.state = {headerLink: "", searchValue: "", random: 0, randomClicks: 0}
this.generateRandom = this.generateRandom.bind(this);
}
getLinkFromHeader = (link) => {
if (this.state.headerLink !== link) {
this.setState({
headerLink: link,
})
}
}
getSearchValueFromHeader = (string) => {
this.setState({
searchValue: string,
});
}
getRandomMax = (max) => {
this.setState({
randomMax: max,
})
}
getRandomClicks = (value) => {
this.setState({
randomClicks: value,
})
}
generateRandom(number) {
let random = Math.floor(Math.random() * number) + 1;
console.log("generateRandom = ", random)
return random
}
shouldComponentUpdate(nextProps, nextState) {
return this.state.randomClicks !== nextState.randomClicks;
}
componentWillUpdate() {}
componentDidUpdate(prevState) {
let randomClicks = this.state.randomClicks;
console.log("this.state.randomClicks: ", this.state.randomClicks)
// console.log("prevState: ", prevState)
// console.log("prevState.randomClicks = ", prevState.randomClicks)
// ^^ is this a bug ? ^^
let random = this.generateRandom(this.state.randomMax);
if (this.state.random !== random) {
this.setState({random: random})
}
}
render() {
return (
<div className="App background">
<div className="content">
<Header getLinkFromHeader={this.getLinkFromHeader} getSearchValueFromHeader={this.getSearchValueFromHeader} randomClick={this.randomClick} getRandomClicks={this.getRandomClicks}/>
<TilesContainer link={this.state.headerLink} searchValue={this.state.searchValue} getRandomMax={this.getRandomMax} random={this.state.random} randomClicks={this.state.randomClicks}/>
</div>
</div>
);
}
}
export default App
Header.js * -每次單擊RandomButton時都會增加randomClick計數
class Header extends Component {
constructor(props){
super(props);
this.state = { selectorLink: "", searchValue: "", randomClicks: 0 }
this.randomClick = this.randomClick.bind(this);
}
getLinkFromSelector = (link) => {
this.setState({
selectorLink: link,
})
}
getSearchValue = (string) => {
this.setState({
searchValue: string,
})
}
shouldComponentUpdate(nextProps, nextState) {
console.log("this.state !== nextState: ", this.state !== nextState)
return this.state !== nextState;
}
componentDidUpdate(previousState){
if(this.state.selectorLink !== previousState.selectorLink) {
this.props.getLinkFromHeader(this.state.selectorLink);
}
this.props.getSearchValueFromHeader(this.state.searchValue);
this.props.getRandomClicks(this.state.randomClicks);
console.log("Header Did Update")
}
randomClick(){
this.props.randomClick;
this.setState({
randomClicks: this.state.randomClicks += 1,
});
}
render(){
return(
<div id="header" className="header">
<div className="title-div">
<div className="h1-wrapper title-wrapper">
<h1>Pokédex Viewer App</h1>
</div>
</div>
<PokedexSelector getLinkFromSelector={this.getLinkFromSelector}/>
<SearchBar getSearchValue={this.getSearchValue}/>
<button type="button" id="random-button" onClick={this.randomClick}>Random Pokémon</button>
<button type="button" id="show-all-button" onClick={this.showAllClick}>Show All</button>
</div>
)
}
}
export default Header
TilesContainer.js-發送來自App的隨機數,並過濾/重新渲染圖塊列表
class TilesContainer extends Component {
constructor(props){
super(props);
this.state = {
pokemon: [],
filteredPokemon: [],
randomMax: 0,
showDetails: false,
};
this.getPokemon = this.getPokemon.bind(this);
this.tiles = this.tiles.bind(this);
this.getPokemon(this.props.link);
}
getPokemon(pokedexLink) {
let link = "";
(pokedexLink === "")
? link = "https://pokeapi.co/api/v2/pokedex/national/"
: link = this.props.link;
fetch(link)
.then(response => response.json())
.then(myJson => {
let list = myJson['pokemon_entries'];
this.setState({
pokemon: list,
randomMax: list.length,
})
this.props.getRandomMax; // send randomMax to App
})
}
filterPokemon(string) {
if (string !== "") {
console.log("string: ", string)
string = string.toString().toLowerCase()
let filteredPokemon = this.state.pokemon.filter(pokemon => {
const name = pokemon.pokemon_species.name;
const nameStr = name.slice(0,string.length);
const number = pokemon.entry_number;
const numberStr = number.toString().slice(0, string.length);
return (this.state.random !== 0) ? number.toString() === string : nameStr === string || numberStr === string;
})
if (this.props.randomClicks !== 0) { // i.e. using a random
this.setState({
filteredPokemon: filteredPokemon,
})
} else {
this.setState({
filteredPokemon: filteredPokemon,
randomMax: filteredPokemon.length,
})
}
} else {
this.setState({
filteredPokemon: [],
randomMax: this.state.pokemon.length,
})
}
}
componentDidUpdate(prevProps, prevState) {
if (this.props.link !== prevProps.link) {
this.getPokemon(this.props.link)
}
if (this.props.searchValue !== prevProps.searchValue) {
this.filterPokemon(this.props.searchValue)
}
if (this.state.randomMax !== prevState.randomMax){
this.props.getRandomMax(this.state.randomMax);
}
if (this.props.random !== prevProps.random) {
console.log("TilesContainer random: ", this.props.random)
this.filterPokemon(this.props.random)
}
}
tiles() {
console.log("tiles() filteredPokemon: ", this.state.filteredPokemon)
console.log("tiles() searchValue: ", this.props.searchValue)
console.log("tiles() random: ", this.props.random)
if (this.state.pokemon.length > 0) {
if (this.state.filteredPokemon.length == 0 && this.props.searchValue === ""){
return (
this.state.pokemon.map(pokemon => (
<Tile key={pokemon.entry_number} number={pokemon.entry_number} name={pokemon.pokemon_species.name} url={pokemon.pokemon_species.url}/>
))
)
} else if (this.state.filteredPokemon.length > 0){
return (
this.state.filteredPokemon.map(pokemon => (
<Tile key={pokemon.entry_number} number={pokemon.entry_number} name={pokemon.pokemon_species.name} url={pokemon.pokemon_species.url}/>
))
)
}
}
}
render(){
return (
<div id="tiles-container"
className="tiles-container">
{this.tiles()}
</div>
)
}
}
export default TilesContainer
您不應在setState
使用當前狀態,也不應直接修改狀態。 而且您實際上並沒有調用this.props.randomClick
,它是未定義的。 更改
randomClick(){
this.props.randomClick;
this.setState({
randomClicks: this.state.randomClicks += 1,
});
}
至
randomClick(){
if (typeof(this.props.randomClick) === 'function') this.props.randomClick();
this.setState(olState => ({
randomClicks: olState.randomClicks + 1,
}));
}
還要檢查您的shouldComponentUpdate
方法。 他們可能是越野車或多余的。 看起來您在state.random
更改時阻止更新App
。 因此,每次單擊按鈕時,您都會存儲新的隨機值,但會使用前一個隨機值。 因此,對於初始渲染和首次單擊,請使用random: 0
。
而且我猜getRandomClicks
應該是setRandomClicks
。
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