[英]How should I instantiate my state from props?
讀左右 ,我看到從getInitialState()/構造道具初始化狀態可以是一個反模式。
從道具初始化狀態並設法保持一致的最佳方法是什么?
如您在下面看到的,我正在嘗試初始化我的“ Card”組件,以便可以初始化一個likeCount和isLikedByMe狀態。 我這樣做是為了讓我可以顯示一個自定義的“喜歡”計數器,並可以通過重置狀態來更改“喜歡”按鈕的文本。
在這一點上,我正在構造函數中執行此操作,但這是錯誤的方法。 我應該如何處理?
import * as React from "react";
import { CardLikeButton } from "./buttons";
export enum CardType {
None = 0,
Text,
Image
}
export interface CardMedia {
text?: string;
imageUrl?: string;
}
export interface CardDetails {
isLikedByMe: boolean;
likeCount: number;
}
export interface CardParams extends React.Props<any> {
cardType: number;
cardId: string;
cardMedia: CardMedia;
cardDetails: CardDetails;
}
export class Card extends React.Component<CardParams, CardDetails> {
state: CardDetails;
constructor(props: CardParams) {
super(props);
console.log("in card constructor");
console.log("card type: " + props.cardType);
this.state = { // setting state from props in getInitialState is not good practice
isLikedByMe: props.cardDetails.isLikedByMe,
likeCount: props.cardDetails.likeCount
};
}
componentWillReceiveProps(nextProps: CardParams) {
this.setState({
isLikedByMe: nextProps.cardDetails.isLikedByMe,
likeCount: nextProps.cardDetails.likeCount
});
}
render() {
console.log("RENDERING CARD");
// console.dir(this.props.cardDetails);
// console.dir(this.props.cardMedia);
// console.dir(this.props.cardType);
if (this.props.cardType === CardType.Text) { // status card
return (
<div className="general-card">
<p>Text card.ID: {this.props.cardId}</p>
<p>{this.props.cardMedia.text}</p>
<CardLikeButton onButClick={this.likeButtonClicked} buttonText={this.state.isLikedByMe ? "Liked" : "Like"} isPressed={this.state.isLikedByMe}/>
<p>Like count: {this.state.likeCount}</p>
</div>
);
} else { //photo card
return (
<div className="general-card">
<p>Image card.ID: {this.props.cardId}</p>
<p> {this.props.cardMedia.text} </p>
<img src={this.props.cardMedia.imageUrl} />
<br/>
<CardLikeButton onButClick={this.likeButtonClicked} buttonText={this.state.isLikedByMe ? "Liked" : "Like"} isPressed={this.state.isLikedByMe}/>
<p>Like count: {this.state.likeCount}</p>
</div>
);
}
}
likeButtonClicked = () => {
console.log('in card => like button clicked!');
var _isLikedByMe = this.state.isLikedByMe;
var _likeCount = this.state.likeCount;
if (_isLikedByMe) {
_likeCount--;
} else {
_likeCount++;
}
_isLikedByMe = !_isLikedByMe;
this.setState({
isLikedByMe: _isLikedByMe,
likeCount: _likeCount
})
}
}
這是主要的列表組件:
/// <reference path="../../typings/index.d.ts" />
import * as React from "react";
import * as ReactDOM from "react-dom";
import {Card} from "./card";
import {CardParams, CardType, CardMedia, CardDetails} from "./card";
var card1: CardParams = {
cardType: CardType.Image,
cardId: "card1234",
cardDetails: {
isLikedByMe: false,
likeCount: 3
},
cardMedia: {
text: "some test text; badescuga",
imageUrl: "http://www9.gsp.ro/usr/thumbs/thumb_924_x_600/2016/06/19/738742-rkx1568-lucian-sinmartean.jpg"
}
};
var card2: CardParams = {
cardId: "card35335",
cardType: CardType.Text,
cardDetails: {
isLikedByMe: true,
likeCount: 1
},
cardMedia: {
text: "some test 2 text"
}
};
var cards = [card1, card2];
ReactDOM.render(
<div>
{
cards.map((item) => {
return (
<Card key={item.cardId} cardId={item.cardId} cardType={item.cardType} cardDetails={item.cardDetails} cardMedia={item.cardMedia}/>
);
})
}
</div>,
document.getElementById("mainContainer")
);
無需接觸Flux或Redux,而是專注於您的問題。
恕我直言,狀態和道具需要分開,其中Card
僅獲得道具,並且狀態是從上方進行管理的。 單擊“贊”按鈕后, Card
組件將獲得引發事件處理程序的功能。 您可以在Card
組件內執行“喜歡”邏輯,然后僅使用該邏輯的輸出引發事件處理程序,例如: this.props.likeClicked(isLikedByMe, updatedLikeCount)
。 或者,在父組件中執行整個邏輯。 我還將所有卡包裝在另一個組件中。
例:
class Card extends React.Component {
constructor(props: CardParams) {
super(props);
}
render() {
return (
<div>
<button onClick={this.likeButtonClicked}>
{this.props.isLikedByMe ? 'Unlike' : 'Like'}
</button>
<p>Like count: {this.props.likeCount}</p>
</div>
)
}
likeButtonClicked = () => {
console.log('in card => like button clicked!');
var _isLikedByMe = this.props.isLikedByMe;
var _likeCount = this.props.likeCount;
if (_isLikedByMe) {
_likeCount--;
} else {
_likeCount++;
}
_isLikedByMe = !_isLikedByMe;
if (this.props.likeUpdated) {
this.props.likeUpdated({
cardId: this.props.cardId,
isLikedByMe: _isLikedByMe,
likeCount: _likeCount
})
}
}
}
class CardList extends React.Component {
constructor(props) {
super(props)
this.state = {
// Could use es6 map
cards: {123: {isLikedByMe: false, likeCount: 3},
124: {isLikedByMe: true, likeCount: 2}}
}
}
_onLikeUpdated({cardId, isLikedByMe, likeCount}) {
const cards = Object.assign({}, this.state.cards)
cards[cardId] = {isLikedByMe, likeCount}
this.setState({cards})
}
_getCards() {
return Object.keys(this.state.cards).map(cardId => {
return <Card key={cardId}
cardId={cardId}
likeUpdated={this._onLikeUpdated.bind(this)}
{...this.state.cards[cardId]} />
})
}
render() {
return <div>
{this._getCards()}
</div>
}
}
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