ReactJS - 卸载和安装时 setState 错误

Question

我是 React 新手，所以我可能不理解正确的思维概念。

我想要自动更新可以安装和卸载的数据组件。

这是我卸载然后安装组件时遇到的错误:

Warning: setState(...): Can only update a mounted or mounting component. This usually means you called setState() on an unmounted component. This is a no-op. Please check the code for the MeasurementsDataTable component.

这是代码:

var getDataInretval;
var listenersService = new ListenersService();
var Data = [{}];

function ListenersService(){
    var listeners = {};
    this.addListener = function(callback){
        var id;
        if(typeof callback === 'function'){
            id = Math.random().toString(36).slice(2);
            listeners[id] = callback;
        }
        return id;
    }
    this.removeListener = function( id){
        if(listeners[id]){
            delete listeners[id];
            return true;
        }
        return false;
    }
    this.notifyListeners = function(data){
        for (var id in listeners) {
            if(listeners.hasOwnProperty(id)){
                listeners[id](data);
            }
        }
    }
}


var dataSevice = new DataMeasurementService(ListenersService);

function DataMeasurementService(ListenersService){

    Data.push( new MeasurementDataForTable("header1", "th", "Phase measurements", "L1", "L2", "L3", "Total", "Others") );
    var self = this;

    //var listenersService = new ListenersService();
    this.addListener = listenersService.addListener;
    this.removeListener = listenersService.removeListener;
    this.getData = function(){
        return Data;
    }

    $.ajax({
        url: "BL/getMeasurementsData.php",
        type: "GET",
        dataType: "html",
        async: false,
        success: function(res) {
            var parseData = parseMeasurementsData( res );
            Data = createOriginData( parseData );
        },
        error: function(request, status, error) {
            alert("error: " + request.responseText);
        }
    });
    listenersService.notifyListeners(Data);
}

var ThElement = React.createClass({
   render: function(){
       return <th  width={this.props.width}>{this.props.data}</th>;
   }
});

var TdElement = React.createClass({
    render: function(){
        return <td>{this.props.data}</td>;
    }
});

var MeasurementsDataTable = React.createClass({
    getInitialState: function() {
        return {
            data: this.props.dataService.getData()
        };
    },
    componentDidMount: function() {
        getDataInretval = setInterval(function(){
            $.ajax({
                url: "BL/getMeasurementsData.php",
                type: "GET",
                dataType: "html",
                async: false,
                success: function(res) {
                    var parseData = parseMeasurementsData( res );
                    Data = createOriginData( parseData );
                },
                error: function(request, status, error) {
                    alert("error: " + request.responseText);
                }
            });

            listenersService.notifyListeners(Data);
        }, 1000);


    },
    componentWillMount: function () {
        this.props.dataService.addListener(this.updateHandler);
    },
    componentWillUnmount: function () {
        this.removeListener = listenersService.removeListener;
        clearInterval(getDataInretval);
    },
    updateHandler: function(data) {
        this.setState({
            data: data
        });
    },
    render: function() {
        return (
            <div>
                <table>
                    {
                        this.state.data.map(function(item) {
                                if( item.element == "th" ){
                                    return (
                                        <thead><tr>
                                            <ThElement width="280" data={item.description}/>
                                            <ThElement width="150" data={item.L1}/>
                                            <ThElement width="150" data={item.L2}/>
                                            <ThElement width="150" data={item.L3}/>
                                            <ThElement width="150" data={item.total}/>
                                            <ThElement width="150" data={item.others}/>
                                        </tr></thead>
                                    )
                                }
                                else{
                                        return (
                                            <tr>
                                                <TdElement data={item.description}/>
                                                <TdElement data={item.L1}/>
                                                <TdElement data={item.L2}/>
                                                <TdElement data={item.L3}/>
                                                <TdElement data={item.total}/>
                                                <TdElement data={item.others}/>
                                            </tr>
                                        )
                                    }
                        })
                    }
               </table>
            </div>
        );
    }
});
ReactDOM.render( <MeasurementsDataTable dataService={dataSevice} />, document.getElementById("tablePlaceHolder") );

Answer 1

您必须确保您的组件在卸载后不会仍在监听附加的事件监听器并尝试更新自身。

在使用 React 时，您需要跟踪所有事件监听器。如果来自事件监听器的数据导致您的组件更新，您必须将监听器附加到生命周期方法 componentWillMount() 并在 componentWillUnmount() 中分离所有监听器。

监听器可以是您的组件监听并通过 setState() 方法自行更改的任何内容。它可以是来自套接字的数据、来自服务器的数据、窗口大小调整事件、setInterval 监听器等。