Question

使用React-Native并尝试学习ES6语法。昨天我遇到了类似的问题并得到了解决方案。我添加了

.bind（本）

到我的函数调用，问题解决了。我又用另一个函数调用遇到了同样的问题，我无法追踪到底发生了什么。错误消息是相同的。

undefined不是对象（评估'this.props.drawer.open'）

功能是：

    onClickMenu () {
    this.props.drawer.open();
  }

正在调用它：

onPress={this.onClickMenu.bind(this)}

这是整个代码。如果您看到的问题不是这个问题看起来不对，请告诉我！ *注意我已将“var”替换为“let”。从我所读到的，到处都是正确的ES6语法？

    'use strict';

const React = require('react-native');
const {
  Text,
  View,
  Component,
  StyleSheet,
  SwitchAndroid
} = React;

import { Button } from 'react-native-material-design';
import Store from 'react-native-simple-store';
import Underscore from 'underscore';
import RNGMap from 'react-native-gmaps';
import Polyline from 'react-native-gmaps/Polyline';
import Icon from 'react-native-vector-icons/Ionicons';
import SettingsService from './../settings/settings.service';
//import subdivisions from './subdivisions.json';
import commonStyles from './../common/styles';

let accessToken = null;
let userId = null;
let routeId = null;
let subdivisionId = null;

SettingsService.init('Android');

class Map extends Component {
  constructor(props) {
    super(props)
    this.state = {
      odometer: 0,
      mapWidth: 300,
      mapHeight: 300,
      enabled: false,
      isMoving: false,
      currentLocation: undefined,
      locationManager: undefined,
      paceButtonIcon: 'Start Trip',
      navigateButtonIcon: 'navigate',
      paceButtonStyle: commonStyles.disabledButton,
      // mapbox
      center: {
        lat: 40.7223,
        lng: -73.9878
      },
      zoom: 10,
      markers: []
    }
  }

  componentDidMount() {
    Store.get('token').then((token) => {
      accessToken = token.access_token;
      userId = token.userId;
    });
    let me = this,
      gmap = this.refs.gmap;

    this.locationManager = this.props.locationManager;

    // location event
    this.locationManager.on("location", function(location) {
      console.log('- location: ', JSON.stringify(location));
      me.setCenter(location);
      gmap.addMarker(me._createMarker(location));

      me.setState({
        odometer: (location.odometer / 1000).toFixed(1)
      });

      // Add a point to our tracking polyline
      if (me.polyline) {
        me.polyline.addPoint(location.coords.latitude, location.coords.longitude);
      }
    });
    // http event
    this.locationManager.on("http", function(response) {});
    // geofence event
    this.locationManager.on("geofence", function(geofence) {});
    // error event
    this.locationManager.on("error", function(error) {
      console.log('- ERROR: ', JSON.stringify(error));
    });
    // motionchange event
    this.locationManager.on("motionchange", function(event) {
      me.updatePaceButtonStyle();
    });

    // getGeofences
    this.locationManager.getGeofences(function(rs) {
    }, function(error) {
      console.log("- getGeofences ERROR", error);
    });

    SettingsService.getValues(function(values) {
      values.license = "eddbe81bbd86fa030ea466198e778ac78229454c31100295dae4bfc5c4d0f7e2";
      values.orderId = 1;
      values.stopTimeout = 0;
      //values.url = 'http://192.168.11.120:8080/locations';

      me.locationManager.configure(values, function(state) {
        me.setState({
          enabled: state.enabled
        });
        if (state.enabled) {
          me.initializePolyline();
          me.updatePaceButtonStyle()
        }
      });
    });

    this.setState({
      enabled: false,
      isMoving: false
    });
  }
  _createMarker(location) {
    return {
      title: location.timestamp,
      id: location.uuid,
      icon: require("image!transparent_circle"),
      anchor: [0.5, 0.5],
      coordinates: {
        lat: location.coords.latitude,
        lng: location.coords.longitude
      }
    };
  }

  initializePolyline() {
    // Create our tracking Polyline
    let me = this;
    Polyline.create({
      width: 12,
      points: [],
      geodesic: true,
      color: '#2677FF'
    }, function(polyline) {
      me.polyline = polyline;
    });
  }

  onClickMenu () {
    this.props.drawer.open();
  }

  onClickEnable() {
    let me = this;
    if (!this.state.enabled) {
      this.locationManager.start(function() {
        me.initializePolyline();
      });
    } else {
      this.locationManager.resetOdometer();
      this.locationManager.stop();
      this.setState({
        markers: [{}],
        odometer: 0
      });
      this.setState({
        markers: []
      });
      if (this.polyline) {
        this.polyline.remove(function(result) {
          me.polyline = undefined;
        });
      }
    }

    this.setState({
      enabled: !this.state.enabled
    });
    this.updatePaceButtonStyle();
  }

  onClickPace() {
    if (!this.state.enabled) {
      return;
    }
    let isMoving = !this.state.isMoving;
    this.locationManager.changePace(isMoving);

    this.setState({
      isMoving: isMoving
    });
    this.updatePaceButtonStyle();
  }

  onClickLocate() {
    let me = this;

    this.locationManager.getCurrentPosition({
      timeout: 30
    }, function(location) {
      me.setCenter(location);
    }, function(error) {
      console.error('ERROR: getCurrentPosition', error);
      me.setState({
        navigateButtonIcon: 'navigate'
      });
    });
  }

  onRegionChange() {}

  setCenter(location) {
    this.setState({
      navigateButtonIcon: 'navigate',
      center: {
        lat: location.coords.latitude,
        lng: location.coords.longitude
      },
      zoom: 16
    });
  }

  onLayout() {
    let me = this,
      gmap = this.refs.gmap;

    this.refs.workspace.measure(function(ox, oy, width, height, px, py) {
      me.setState({
        mapHeight: height,
        mapWidth: width
      });
    });
  }

  updatePaceButtonStyle() {
    let style = commonStyles.disabledButton;
    if (this.state.enabled) {
      style = (this.state.isMoving) ? commonStyles.redButton : commonStyles.greenButton;
    }
    this.setState({
      paceButtonStyle: style,
      paceButtonIcon: (this.state.enabled && this.state.isMoving) ? 'Stop Trip' : 'Start Trip'
    });
  }

  render() {
    return (
      <View style={commonStyles.container}>
        <View style={commonStyles.topToolbar}>
          <Icon.Button name="android-options" onPress={this.onClickMenu.bind(this)} backgroundColor="transparent" size={30} color="#000" style={styles.btnMenu} underlayColor={"transparent"} />
          <Text style={commonStyles.toolbarTitle}>Background Geolocation</Text>
          <SwitchAndroid onValueChange={this.onClickEnable.bind(this)} value={this.state.enabled} />
        </View>
        <View ref="workspace" style={styles.workspace} onLayout={this.onLayout.bind(this)}>

          <RNGMap
            ref={'gmap'}
            style={{width: this.state.mapWidth, height: this.state.mapHeight}}
            markers={this.state.markers}
            zoomLevel={this.state.zoom}
            onMapChange={(e) => console.log(e)}
            onMapError={(e) => console.log('Map error --> ', e)}
            center={this.state.center} />

        </View>
        <View style={commonStyles.bottomToolbar}>
          <Icon.Button name={this.state.navigateButtonIcon} onPress={this.onClickLocate.bind(this)} size={25} color="#000" underlayColor="#ccc" backgroundColor="transparent" style={styles.btnNavigate} />
          <Text style={{fontWeight: 'bold', fontSize: 18, flex: 1, textAlign: 'center'}}>{this.state.odometer} km</Text>
          <Button raised={true} 
                  text={this.state.paceButtonIcon} 
                  onPress={this.onClickPace.bind(this)}
                  overrides={{backgroundColor:"#e12429",textColor:"#ffffff"}} 
                  style={this.state.paceButtonStyle}></Button>
          <Text>&nbsp;</Text>
        </View>
      </View>
    );
  }
};

const styles = StyleSheet.create({
  workspace: {
    flex: 1
  }
});

module.exports = Map;

更新：通过终端中的adb进行调试显示相同的错误

所以这是其余的代码。排除故障。我将项目文件添加到了plunker。这是我正在使用的演示项目。 plunker

    'use strict';

const React = require('react-native');
const {
  Text, 
  Component,
  StyleSheet, 
  AppRegistry
} = React;

import Map from './map/map';
import Drawer from 'react-native-drawer';
import Settings from './settings/settings.android';
import Icon from 'react-native-vector-icons/Ionicons';
import BackgroundGeolocation from 'react-native-background-geolocation-android';

global.bgGeo = BackgroundGeolocation;

class App extends Component {
  onClickMenu() {
    this.props.refs.drawer.open();
  }

  render() {
    return (
      <Drawer ref="drawer" side="right" acceptPan={false} content={<Settings drawer={this.refs.drawer} locationManager={BackgroundGeolocation} />}>
        <Map drawer={this.refs.drawer} locationManager={BackgroundGeolocation} />    
      </Drawer>
    );
  }
};

module.exports = App;

更新：

Answer 1

我认为你不能以这种方式将refs传递给组件，当然它不会在React中起作用，我认为它不会起作用以这种方式React-Native。

我不清楚你为什么试图.open来自Drawer Map组件看起来只有Map组件在Drawer打开时访问，但是，如果您想访问父级来自儿童的行为良好的模式是通过功能让孩子们执行（你可能会说这实际上很糟糕并且传递事件是一种更强大的模式。）

我从来没有使用过这个库，所以我对它的用法并不完全清楚你可以像这样传递函数：

class Application extends Component {

  closeControlPanel = () => {
    this.refs.drawer.close()
  };
  openControlPanel = () => {
    this.refs.drawer.open()
  };
  render () {
    return (
      <Drawer
        ref="drawer"
        content={<ControlPanel />}
        >
        <Map onMenuClose={ this.closeControlPanel.bind( this ) } />
      </Drawer>
    )
  }
})

在这种情况下，this.props.onMenuClose应该附加到一个动作，当执行该动作时，它将触发父动作并执行this.refs.drawer.close功能。

如何使用ES6与本机反应

1 个答案: