如何通过点击create-react-app中的按钮来访问位于另一个js文件中的另一个组件的函数

Question

我有两个文件index.js和map.js。在map.js中，我有Kartta组件，该组件包含一个传单映射和一个方法fetchAll()，该方法根据从API(在本例中为test.json(获得的坐标在映射上创建标记。如果我将该方法放入componentDidMount()，它在加载时创建标记。然而，我想通过点击按钮"Haku"来创建这些标记，该按钮位于index.js中的边栏组件内。

这是map.js

import React, { Component } from 'react';
import L from 'leaflet';
import { Map, Marker, Popup, TileLayer } from 'react-leaflet';
import { fetchAll } from './search';
const position = [62.241581, 25.758742];
class Kartta extends Component {
state = {
kohteet: []
}
componentDidMount() {
this.fetchAll();
}
fetchAll = () => {
console.log("täällä");
fetch('test.json')
.then(res => res.json())
.then((data) => {
this.setState({ kohteet: data })
})
.catch(console.log(this.state.kohteet))
}
iconSize = (iconName) => {
if (iconName == 'tree.png') {
return 30, 30
}
else {
return 15, 30
}
}
render() {
return (
<div id="mapid" className="h-100 w-100">
<Map center={position} zoom={7}>
<button onClick={this.haeKaikki}>Hae</button>
<TileLayer
url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
attribution="&copy; <a href=&quot;http://osm.org/copyright&quot;>OpenStreetMap</a> contributors"
/>
{this.state.kohteet.map((kohde) => (
<Marker key={'key' + kohde.id} position={[kohde.lon, kohde.lat]} icon={
new L.Icon({
iconUrl: require('../img/' + kohde.icon),
iconSize: new L.Point(this.iconSize(kohde.icon)),
id: kohde.id + kohde.icon
})
}>
<Popup>
<h1>{kohde.name}</h1>
<p>{kohde.desc}</p>
</Popup>
</Marker>
))}
</Map>
</div>
)
}
}
export default Kartta

这里是index.js

import React, { Component } from 'react';
import ReactDOM from 'react-dom';
import './css/main.css';
import 'bootstrap/dist/js/bootstrap.bundle.js';
import 'leaflet/dist/leaflet.css';
import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
import { faSearch, faInfoCircle } from '@fortawesome/free-solid-svg-icons';
import Kartta from './components/map';
// Yläpalkki
class Navbar extends React.Component {
render() {
return (
<nav id="nav-bar" className="navbar navbar-expand-lg navbar-dark bg-primary">
<a id="nav-bar-a0" className="navbar-brand" href="/">MeijänMetsät</a>
<button id="toggle-search-btn" type="button" href="#sidebar" data-toggle="collapse" className="btn btn-primary">
<FontAwesomeIcon icon={faSearch} />
<span> Haku</span>
</button>
<ul id="nav-bar-ul0" className="navbar-nav mr-auto">
</ul>
<div id="nav-bar-div0" className="dropdown">
<button id="nav-bar-button0" className="btn btn-primary dropdown-toggle" type="button" data-toggle="dropdown">Kirjaudu
<span id="nav-bar-span0" className="caret"></span></button>
<div id="dropdown-div0" className="p-2 dropdown-menu dropdown-menu-right" style={{"minWidth":"350px"}}>
<form id="dropdown-form0">
<div id="dropdown-div1" className="form-group">
<label id="dropdown-label0" htmlFor="exampleInputEmail1">Sähköposti</label>
<input id="dropdown-input0" type="email" className="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Syötä sähköposti" />
</div>
<div id="dropdown-div2" className="form-group">
<label id="dropdown-label1" htmlFor="exampleInputPassword1">Salasana</label>
<input id="dropdown-input1" type="password" className="form-control" id="exampleInputPassword1" placeholder="Salasana" />
</div>
<div id="dropdown-div3" className="row">
<button id="dropdown-button0" type="submit" className="ml-3 btn btn-primary">Kirjaudu</button>
<button id="dropdown-button2" type="submit" className="ml-2 btn btn-primary">Rekiströidy</button>
<button id="dropdown-button1" type="submit" className="ml-2 btn btn-secondary">Facebook</button>
</div>
</form>
</div>
</div>
</nav>
);
}
}
// Sivupalkki
class Sidebar extends React.Component {
render() {
return (
<div className="p-2 collapse in" id="sidebar">
<div className="list-group panel" id="sidebar-div0">
<form id="sidebar-form0">
<div id="sidebar-div01" className="form-group active">
<label id="sidebar-label0" htmlFor="exampleInputEmail1">Kohteen nimi</label><span> </span>
<FontAwesomeIcon icon={faInfoCircle} className="pointer dropdown-toggle" data-toggle="dropdown" alt="Hakuohjeet" />
<div id="search-info" className="p-2 dropdown-menu dropdown-menu-right">
<p>Hae kirjoittamalla tägejä</p>
</div>
<div className="row">
<div className="col-7 ml-3 p-0">
<input type="text" className="form-control" id="searchByName" aria-describedby="emailHelp" placeholder="Syötä kohteen nimi" />
</div>
<button id="sidebar-button0" type="submit" className="btn btn-primary ml-2 col-3" onClick={() => Kartta.fetchAll}>Haku</button>
</div>
</div>
</form>
<div id="sidebar-div02" className="dropdown">
<a id="sidebar-button1" className="btn btn-light dropdown-toggle p-0 thaku" type="button" data-toggle="dropdown">Tarkennettu haku
<span id="sidebar-span0" className="caret"></span></a>
<div id="sidebar-div020" className="p-0 dropdown-menu border-0 mt-2 w-100 h-100">
<form id="sidebar-form1">
<div id="sidebar-div0200" className="form-group p-0">
<label id="sidebar-label1" htmlFor="exampleInputEmail1">Paikkakunta</label>
<input id="sidebar-input1" type="text" className="form-control" placeholder="Syötä paikkakunta" />
</div>
<div id="ch-div0" className="row pl-3">
<label id="lbl-location">Sijainti</label>
<input id="ch-location" className="mt-2 ml-2" type="checkbox" aria-label="Checkbox for following text input" />
</div>
<div className="input-group mb-3">
<div className="input-group-prepend">
<label className="input-group-text" htmlFor="inputGroupSelect01">Palvelut</label>
</div>
<select className="custom-select" id="inputGroupSelect01">
<option defaultValue>Valitse...</option>
<option value="1">Kakkapaikka</option>
<option value="2">Pissapaikka</option>
<option value="3">Kaljapaikka</option>
</select>
</div>
<div id="dropdown-div3" className="row p-0">
<button id="dropdown-button0" type="submit" className="ml-3 btn btn-primary">Tarkennettu haku</button>
</div>
</form>
</div>
</div>
</div>
</div>
);
}
}
// Sisältö
class Content extends React.Component {
render() {
return (
<div id="main-container" className="container-fluid h-100 p-0">
<Navbar />
<div id="container0" className="row h-100 w-100 m-0 wrapper">
<Sidebar />
<div id="container02" className="col h-100 w-100 p-0">
<Kartta />
</div>
</div>
</div>
);
}
}
ReactDOM.render(<Content />, document.getElementById('root'));

按钮"Haku"有onClick={() => Kartta.fetchAll}，但它什么都不做，甚至没有访问fetchAll()功能。如果我在地图上创建按钮，该功能会很好地工作，但我不想这样做，按钮必须在边栏上，因为计划将来使用搜索词。

谢谢！

Answer 1

您需要在Kartta组件中创建一个prop，例如createmap:boolean。现在，在index.js中，首先需要创建一个状态，例如createmap:boolean(最初设置为false(，点击Haku按钮，需要设置状态：

this.setState({
creatmap:true;
});

您需要在index.jsrender()函数中包括Katta组件JSX，例如

<Kartta createmap = {this.state.createmap} />

现在，在componentDidMount()上的Kartta组件中，您可以检查createmap' prop and based on its value call the functionfetchAll((`：

public componentDidMount() {
if(this.prop.createmap) {
fetchAll();
}
}

这将导致由于点击按钮时的设置状态而重新报价，并且如果发现createMaptrue，将调用"fetchAll(("函数

希望这能有所帮助。

编辑：

不要忘记在Kartta组件类中使用export关键字，这样您就可以在index.js中导入它，在render():中创建它的JSX

export default class Kartta extends Component { ... }

编辑2

在导航栏组件类中，初始化构造函数中的state：

export default class NavBar extends Component {
constructor(props) {
super(props);
this.state: {
createmap: false;
}
}
}

您的Kartta组件类别：

export default class Kartta extends Component {
constructor(props) {
super(props); 
}
componentDidMount() {
if(this.props.createmap) {
fetchAll();
}
}