如何解决使用反应状态更改谷歌地图方向
目标是当我单击方向 1 按钮时,谷歌地图会呈现该方向,而当单击方向 2 按钮时,地图会在谷歌地图上显示其他方向。我试图在 handleClick1-2 时更改地址状态,但在 handleClick 函数中 console.logs 在控制台上显示未定义,所以我想我需要对更新状态做一些事情。我将代码简化为易于理解,根据要求,我也可以将谷歌地图功能添加到问题中。我已经很感激了。
我的地图组件
const addresses1 = [
{
latitude: 33.000,longitude: -84.000,},{
latitude: 36.000,longitude: -80.000,}
];
const addresses2 = [
{
latitude: 35.000,longitude: -74.000,{
latitude: 32.000,}
];
class Map extends Component {
constructor(props) {
super(props);
this.state = {
addresses: addresses1,directions: null,prevAddresses: null,};
}
componentDidMount() {
this.getDirections(this.state.addresses);
}
handleClick1 = () => {
this.setState({ addresses: addresses1 });
console.log(this.addresses); // <--- shows undefined
};
handleClick2 = () => {
this.setState({ addresses: addresses2 });
console.log(this.addresses); // <--- also shows undefined
};
render() {
//... makers and direction functions
return (
<>
<DirectionsGoogleMap ...>
<Button onClick={this.handleClick1} > Direction1 </Button>
<Button onClick={this.handleClick2} > Direction2 </Button>
</>
);
}
}
export default Map;
解决方法
你在使用任何谷歌地图反应库吗?在您的代码段中有一条注释 console.log(this.addresses); // <--- shows undefined
。您需要像这样调用它 console.log(this.state.addresses);
以获取状态变量 addresses
的值。
我还可以看到您正在呼叫 <DirectionsGoogleMap ...>
。您如何在路线服务中传递 this.state.addresses
?
下面是一个 sample code 和代码片段,说明我如何使用带有内嵌注释的 @react-google-maps/api
库来实现这一点:
Index.js
import React from "react";
import { render } from "react-dom";
import { LoadScript } from "@react-google-maps/api";
import Map from "./Map";
import "./style.css";
const lib = ["places"];
const key = ""; // PUT GMAP API KEY HERE
class App extends React.Component {
render() {
return (
<LoadScript googleMapsApiKey={key} libraries={lib}>
<Map />
</LoadScript>
);
}
}
render(<App />,document.getElementById("root"));
Map.js
import React,{ Component } from "react";
import DirectionsMap from "./DirectionsMap";
let addresses1 = [
{
lat: 33.0,lng: -84.0
},{
lat: 36.0,lng: -80.0
}
];
let addresses2 = [
{
lat: 34.0,{
lat: 33.0,lng: -84.0
}
];
class Map extends Component {
constructor(props) {
super(props);
this.state = {
addresses: addresses1
};
}
handleClick1 = () => {
this.setState({ addresses: addresses1 });
};
handleClick2 = () => {
this.setState({ addresses: addresses2 });
};
render() {
//... makers and direction functions
return (
<div>
<DirectionsMap coords={this.state.addresses} />
<button onClick={this.handleClick1}> Direction1 </button>
<button onClick={this.handleClick2}> Direction2 </button>
</div>
);
}
}
export default Map;
DirectionsMap.js
/*global google*/
import React from "react";
import { GoogleMap,DirectionsRenderer } from "@react-google-maps/api";
const defaultLocation = {
lat: 32.0,lng: -84.0
};
let directionsService;
class DirectionsMap extends React.Component {
constructor(props) {
super(props);
}
state = {
directions: null
};
//this will load the directions in map load
onMapLoad = map => {
directionsService = new google.maps.DirectionsService();
this.changeDirection(this.props.coords[0],this.props.coords[1]);
};
//this will check if your props changes and render the new value of your props the props will be the parameter you passed inside <DirectionsMap /> in DirectionsMap.js
componentDidUpdate = prevProps => {
if (prevProps !== this.props) {
this.changeDirection(this.props.coords[0],this.props.coords[1]);
}
};
//function that is calling the directions service
changeDirection = (origin,destination) => {
directionsService.route(
{
origin: origin,destination: destination,travelMode: google.maps.TravelMode.DRIVING
},(result,status) => {
if (status === google.maps.DirectionsStatus.OK) {
//changing the state of directions to the result of direction service
this.setState({
directions: result
});
} else {
console.error(`error fetching directions ${result}`);
}
}
);
};
render() {
return (
<div>
<GoogleMap
center={defaultLocation}
zoom={5}
onLoad={map => this.onMapLoad(map)}
mapContainerStyle={{ height: "400px",width: "800px" }}
>
{this.state.directions !== null && (
<DirectionsRenderer directions={this.state.directions} />
)}
</GoogleMap>
</div>
);
}
}
export default DirectionsMap;
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