复选框为 checked/unchecked 时管理状态 - React

Question

在我的 React 应用程序中，用户输入关键字并获得结果列表。我正在尝试对这些结果实施过滤器。下面是过滤器的屏幕截图。

这是我的状态

class SearchResultsPage  extends React.Component{
    constructor(props) {
        super(props);
        this.state = {
            results: this.props.location.state.data.results,
            keyword: this.props.location.state.data.keyword,
            pageOfItems: [],
            cities: {
                'New York City (NYC)': false,
                'Delhi': false,
                'Bangkok': false,
                'Paris': false,
                'Mexico City': false
            },
            topics: {
                'Environment': false,
                'Crime': false,
                'Politics': false,
                'Social Unrest': false,
                'Infrastructure': false
            },
            languages: {
                'Hindi': false,
                'English': false,
                'Thai': false,
                'French': false,
                'Spanish': false
            }
        };
        this.onChangePage = this.onChangePage.bind(this);
        this.onCityChange = this.onCityChange.bind(this);
    }

我想做的是，无论何时选中或取消选中一个复选框，我都会将相应的复选框设置为 true/false。基于每个复选框的布尔值，我过滤掉 results，然后在 UI 上渲染它。单击复选框时，我可以过滤结果，但取消选中复选框时，我无法显示所有结果。这就是我在复选框更改时的处理方式。

onCityChange(e) {
        const val = e.target.checked;
        const name = e.target.name;
        let updatedCities = Object.assign({},this.state.cities,{[name]: val});
        this.setState({
            cities: updatedCities,
        },function () {
            const filteredCities = [];
            for (let key in this.state.cities) {
                if (this.state.cities[key] === true) {
                    filteredCities.push(key)
                }
            }
            const filteredResults = [];
            this.state.results.forEach((result) => {
                for (let i = 0; i < filteredCities.length; i++) {
                    if (result.city === filteredCities[i] && result.city != null) {
                        filteredResults.push(result)
                    }
                }
            })
            console.log(filteredResults.length)
            if (filteredResults.length > 0) {
                this.setState({
                    results: filteredResults
                })
            }
        })
    }

我知道我没有正确处理状态，在这种情况下我该怎么办。为了更好地参考，这里是完整的搜索结果代码。

import React from 'react';
import NavigationBar from './NavigationBar';
import SearchPageResultsStyle from "../assets/css/SearchResultsPage.css"
import Pagination from './Pagination';

class SearchResultsPage  extends React.Component{
    constructor(props) {
        super(props);
        this.state = {
            results: this.props.location.state.data.results,
            keyword: this.props.location.state.data.keyword,
            pageOfItems: [],
            cities: {
                'New York City (NYC)': false,
                'Delhi': false,
                'Bangkok': false,
                'Paris': false,
                'Mexico City': false
            },
            topics: {
                'Environment': false,
                'Crime': false,
                'Politics': false,
                'Social Unrest': false,
                'Infrastructure': false
            },
            languages: {
                'Hindi': false,
                'English': false,
                'Thai': false,
                'French': false,
                'Spanish': false
            }
        };
        this.onChangePage = this.onChangePage.bind(this);
        this.onCityChange = this.onCityChange.bind(this);
    }

    onChangePage(pageOfItems) {
        // update local state with new page of items
        this.setState({pageOfItems});
    }

    // setting each city in cities object (city chechboxes which are clicked on UI) to true
    onCityChange(e) {
        const val = e.target.checked;
        const name = e.target.name;
        let updatedCities = Object.assign({},this.state.cities,{[name]: val});
        this.setState({
            cities: updatedCities,
        },function () {
            const filteredCities = [];
            for (let key in this.state.cities) {
                if (this.state.cities[key] === true) {
                    filteredCities.push(key)
                }
            }
            const filteredResults = [];
            this.state.results.forEach((result) => {
                for (let i = 0; i < filteredCities.length; i++) {
                    if (result.city === filteredCities[i] && result.city != null) {
                        filteredResults.push(result)
                    }
                }
            })
            console.log(filteredResults.length)
            if (filteredResults.length > 0) {
                this.setState({
                    results: filteredResults
                })
            }
        })
    }

    // rendering checkboxes for topics
    renderCityFilter() {
        const cities = ['New York City (NYC)','Delhi','Bangkok','Paris','Mexico City']
        return cities.map((city,i) => {
            return (
                <div key={i} className={'city-filters'}>
                    <input
                        type="checkbox"
                        name={city}
                        onChange={this.onCityChange}
                        value={this.state.cities[city]}/>&nbsp;&nbsp;
                    <label key={i} style={{fontSize:12}}>
                        {city}
                    </label>
                </div>

            )
        })
    }

    // rendering checkboxes for topics
    renderTopicFilter() {
        const topics = ['Environment','Crime','Politics','Social Unrest','Infrastructure']
        return topics.map((topic,i) => {
            return (
                <div key={i}>
                    <input
                        type="checkbox"
                        name={topic}
                        onChange={this.onCityChange}
                        value={this.state.topics[topic]}/>&nbsp;&nbsp;
                    <label key={i} style={{fontSize:12}}>
                        {topic}
                    </label>
                </div>

            )
        })
    }

    // rendering checkboxes for languages
    renderLanguageFilter() {
        const languages = ['Hindi','English','Thai','French','Spanish']
        return languages.map((language,i) => {
            return (
                <div key={i}>
                    <input
                        type="checkbox"
                        name={language}
                        onChange={this.onCityChange}
                        value={this.state.languages[language]}/>&nbsp;&nbsp;
                    <label key={i} style={{fontSize:12}}>
                        {language}
                    </label>
                </div>

            )
        })
    }

    render() {

        const renderItems = this.state.pageOfItems.map((item, index) => {
            return (
                <div key={index}>
                    <h3 style={{color: '#1a0dab'}} key={index}>{item.text}</h3>
                    <a href={'https://google.com'} key={index}>{item.tweetUrl}</a>
                    <br/>
                    <p><span style={{fontWeight:'bold', textColor:'#6a6a6a'}} key={index}>topic: </span>{item.topic}</p>
                    <p><span style={{fontWeight:'bold', textColor:'#6a6a6a'}} key={index}>city: </span>{item.city}</p>
                    <p><span style={{fontWeight:'bold', textColor:'#6a6a6a'}} key={index}>lang: </span>{item.lang}</p>
                    <p><span style={{fontWeight:'bold', textColor:'#6a6a6a'}} key={index}>Hashtags: </span></p>
                    <hr/>
                </div>
            )
        });

        return (
            <div>
                <NavigationBar/>
                <h4 style={{textAlign:'center', color:'#1a0dab'}}>Showing search results for <span style={{fontWeight:'bold', fontStyle:'Italic'}}>'{this.state.keyword}'</span></h4>
                <hr/>
                <div className={'wrap'} style={SearchPageResultsStyle}>
                    <div className={'fleft'}>
                        <h4>City</h4>
                        {this.renderCityFilter()}
                        <hr/>
                        <h4>Topics</h4>
                        {this.renderTopicFilter()}
                        <hr/>
                        <h4>Language</h4>
                        {this.renderLanguageFilter()}
                        <hr/>
                    </div>
                    <div className={'fcenter'}>
                        {renderItems}
                        <Pagination items={this.state.results} onChangePage={this.onChangePage}/>
                    </div>
                    <div className={'fright'}/>
                </div>
            </div>
        )
    }
}

export default SearchResultsPage;

Answer 1

尝试单独实现过滤状态，而不是与 results 结合使用，看看我的解决方案：

import React from 'react';
import NavigationBar from './NavigationBar';
import SearchPageResultsStyle from "../assets/css/SearchResultsPage.css"
import Pagination from './Pagination';

class SearchResultsPage  extends React.Component{
    constructor(props) {
        super(props);
        this.state = {
            results: this.props.location.state.data.results,
            isFiltered: false, //NEW STATE
            filteredResults: [], //NEW STATE
            keyword: this.props.location.state.data.keyword,
            pageOfItems: [],
            cities: {
                'New York City (NYC)': false,
                'Delhi': false,
                'Bangkok': false,
                'Paris': false,
                'Mexico City': false
            },
            topics: {
                'Environment': false,
                'Crime': false,
                'Politics': false,
                'Social Unrest': false,
                'Infrastructure': false
            },
            languages: {
                'Hindi': false,
                'English': false,
                'Thai': false,
                'French': false,
                'Spanish': false
            }
        };
        this.onChangePage = this.onChangePage.bind(this);
        this.onCityChange = this.onCityChange.bind(this);
    }

    onChangePage(pageOfItems) {
        // update local state with new page of items
        this.setState({pageOfItems});
    }

    // setting each city in cities object (city chechboxes which are clicked on UI) to true
    onCityChange(e) {
        const val = e.target.checked;
        const name = e.target.name;
        let updatedCities = Object.assign({},this.state.cities,{[name]: val});
        this.setState({
            cities: updatedCities,
        },function () {
            const filteredCities = [];
            for (let key in this.state.cities) {
                if (this.state.cities[key] === true) {
                    filteredCities.push(key)
                }
            }
            // CHECK IF SHOULD FILTER
            if (filteredCities.length > 0) {
                const filteredResults = [];
                this.state.results.forEach((result) => {
                    for (let i = 0; i < filteredCities.length; i++) {
                        if (result.city === filteredCities[i] && result.city != null) {
                            filteredResults.push(result)
                        }
                    }
                })
                console.log(filteredResults.length)
                if (filteredResults.length > 0) {
                    this.setState({
                        isFiltered: true,
                        filteredResults: filteredResults
                    })
                }
            } else {
                this.setState({
                    isFiltered: false,
                    filteredResults: []
                })
            }
        })
    }

    // rendering checkboxes for topics
    renderCityFilter() {
        const cities = ['New York City (NYC)','Delhi','Bangkok','Paris','Mexico City']
        return cities.map((city,i) => {
            return (
                <div key={i} className={'city-filters'}>
                    <input
                        type="checkbox"
                        name={city}
                        onChange={this.onCityChange}
                        value={this.state.cities[city]}/>&nbsp;&nbsp;
                    <label key={i} style={{fontSize:12}}>
                        {city}
                    </label>
                </div>

            )
        })
    }

    // rendering checkboxes for topics
    renderTopicFilter() {
        const topics = ['Environment','Crime','Politics','Social Unrest','Infrastructure']
        return topics.map((topic,i) => {
            return (
                <div key={i}>
                    <input
                        type="checkbox"
                        name={topic}
                        onChange={this.onCityChange}
                        value={this.state.topics[topic]}/>&nbsp;&nbsp;
                    <label key={i} style={{fontSize:12}}>
                        {topic}
                    </label>
                </div>

            )
        })
    }

    // rendering checkboxes for languages
    renderLanguageFilter() {
        const languages = ['Hindi','English','Thai','French','Spanish']
        return languages.map((language,i) => {
            return (
                <div key={i}>
                    <input
                        type="checkbox"
                        name={language}
                        onChange={this.onCityChange}
                        value={this.state.languages[language]}/>&nbsp;&nbsp;
                    <label key={i} style={{fontSize:12}}>
                        {language}
                    </label>
                </div>

            )
        })
    }

    render() {

        const renderItems = this.state.pageOfItems.map((item, index) => {
            return (
                <div key={index}>
                    <h3 style={{color: '#1a0dab'}} key={index}>{item.text}</h3>
                    <a href={'https://google.com'} key={index}>{item.tweetUrl}</a>
                    <br/>
                    <p><span style={{fontWeight:'bold', textColor:'#6a6a6a'}} key={index}>topic: </span>{item.topic}</p>
                    <p><span style={{fontWeight:'bold', textColor:'#6a6a6a'}} key={index}>city: </span>{item.city}</p>
                    <p><span style={{fontWeight:'bold', textColor:'#6a6a6a'}} key={index}>lang: </span>{item.lang}</p>
                    <p><span style={{fontWeight:'bold', textColor:'#6a6a6a'}} key={index}>Hashtags: </span></p>
                    <hr/>
                </div>
            )
        });

        return (
            <div>
                <NavigationBar/>
                <h4 style={{textAlign:'center', color:'#1a0dab'}}>Showing search results for <span style={{fontWeight:'bold', fontStyle:'Italic'}}>'{this.state.keyword}'</span></h4>
                <hr/>
                <div className={'wrap'} style={SearchPageResultsStyle}>
                    <div className={'fleft'}>
                        <h4>City</h4>
                        {this.renderCityFilter()}
                        <hr/>
                        <h4>Topics</h4>
                        {this.renderTopicFilter()}
                        <hr/>
                        <h4>Language</h4>
                        {this.renderLanguageFilter()}
                        <hr/>
                    </div>
                    <div className={'fcenter'}>
                        {renderItems}
                        {//CHECK SHOULD RENDER RESULTS OR FILTEREDRESULTS}
                        <Pagination items={this.state.isFiltered ? this.state.filteredResults : this.state.results} onChangePage={this.onChangePage}/>
                    </div>
                    <div className={'fright'}/>
                </div>
            </div>
        )
    }
}

export default SearchResultsPage;

复选框为 checked/unchecked 时管理状态 - React

Manage State when checkbox is checked/unchecked - React

javascript

checkbox

reactjs

react-state-management

react-state