reactjs - 如何在 ReactJs 中将默认值设置为道具？

问题描述

我有一系列数据，其中包含数组（json 文件）中的一些对象，它将通过fetch请求显示。有一个renderMinTotal()函数必须让我得到totalcomjson 文件所有数据的最小输入数。这个函数可以正常工作，但是我希望默认值FilterTotal是renderMinTotal(). 为此我写了这段代码：

  let defaultFilterTotal = null;
  defaultFilterTotal = FilterTotal
  ? (FilterTotal) 
  : (this.renderMinTotal ());

但默认值为空。为什么它没有被设置为默认值 FilterTotal？

class App extends React.Component {
constructor(props) {
    super(props);
    this.state = {
        data: [],
        library: null,
        perPage: 20,
        currentPage: 1,
        maxPage: null,
        FilterTotal: "",
    };
}
componentDidMount() {
    fetch('/json.bc', {
        method: 'get',
    })
        .then(response => response.text())
        .then(text => {
            let Maindata = JSON.parse(text.replace(/\'/g, '"'))
            this.setState(state => ({
                ...state,
                data: Maindata
            }), () => {
                this.reorganiseLibrary()
            })
        }).catch(error => console.error(error))
}
reorganiseLibrary = () => {
    const { FilterTotal, perPage, data } = this.state;
    let library = data;
    let defaultFilterTotal = null;
    defaultFilterTotal = FilterTotal
        ? (FilterTotal)
        : (this.renderMinTotal()); //The default value of FilterTotal is not been set .////
    if (FilterTotal !== "") {
        library = library.filter(item =>
            item.totalCom > FilterTotal
        )
    }
    library = _.chunk(library, perPage);
    this.setState({
        library,
        currentPage: 1,
        maxPage: library.length === 0 ? 1 : library.length
    })
}

// Previous Page
previousPage = event => {
    this.setState({
        currentPage: this.state.currentPage - 1
    })
}
// Next Page 
nextPage = event => {
    this.setState({
        currentPage: this.state.currentPage + 1
    })
}

// handle per page
handlePerPage = (evt) =>
    this.setState({
        perPage: evt.target.value
    }, () => this.reorganiseLibrary());

// handle render of library
renderLibrary = () => {
    const { library, currentPage } = this.state;
    if (!library || (library && library.length === 0)) {
        return <div className="nodata">No Result</div>
    }
    return library[currentPage - 1].sort((a, b) => a.total - b.total).map((item, i) => (
        <div className="item">
            <span>{this.renderTotalcom(item)}</span>
        </div>
    ))
}
// handle render of library
renderMinTotal = () => {
    const { library } = this.state;
    if (!library || (library && library.length === 0)) {
        return ''
    }
    return library.reduce((acc, lib) => {
        const libMin = Math.min(...lib.map(item => item.totalCom))
        return acc === undefined ? libMin : libMin < acc ? libMin : acc
    }, undefined)
}
render() {
    const { library, currentPage, perPage, maxPage } = this.state;
    return (
        <div>
            <span className="max">{this.renderMinTotal()}</span>
            {this.renderLibrary()}
            <ul id="page-numbers">
                <li className="nexprevPage">
                    {currentPage !== 1 && (
                        <button onClick={this.previousPage}><span className="fa-backward"></span></button>
                    )}
                </li>
                <li className="controlsPage active">{this.state.currentPage}</li>
                <li className="restControls">...</li>
                <li className="controlsPage">{this.state.maxPage}</li>
                <li className="nexprevPage">
                    {(currentPage < maxPage) && (<button onClick={this.nextPage}><span className="fa-forward"></span></button>
                    )}
                </li>
            </ul>
        </div>
    )
}
renderTotalcom(element) {
    return element.totalCom
 }
 }
 ReactDOM.render(<App />, document.getElementById('Result'))

标签： reactjs

reactjs - 如何在 ReactJs 中将默认值设置为道具？

问题描述

解决方案

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