类型错误：无法读取属性“receiptnumber”的未定义的反应本地

问题描述：

我在状态这些属性我的组件类型错误：无法读取属性“receiptnumber”的未定义的反应本地

constructor(props) { 
    super(props); 
    this._onPress = this._onPress.bind(this); 
    this.state = { 
    receiptnumber: "", 
    text: "", 
    time: "", 
    isDateTimePickerVisible: false 
    }; 
}

我已绑定在其上运行得很好按钮的单击事件_onPress方法。我打电话给另一种方法_saveScheduleMessage内_onPress方法，我试图访问this.state.receiptnumber我收到一个错误。

_onPress() { 
    try { 
     if (Platform.OS === "android") { 
     if (Platform.Version >= 23) { 
      Promise.resolve(requestSendSMSPermission()).then(function(result) { 
      // user granted SMS permission 
      if (result) { 
       this._saveScheduleMessage; 
      } else { 
       // user denied SMS permission 
       Alert.alert(
       strings.permission_required, 
       strings.send_sms_deny_permission 
      ); 
      } 
      }); 
     } 
     } 
    } catch (error) { 
    console.log(error); 
    } 
} 

_saveScheduleMessage() { 
    realm.write(() => { 
    realm.create("NewMessage", { 
     receiptNumber: this.state.receiptnumber, 
     text: this.state.text, 
     time: this.state.time 
    }); 
    }); 
    const resetAction = NavigationActions.reset({ 
    index: 0, 
    actions: [ 
     NavigationActions.navigate({ 
     routeName: "DashboardScreen" 
     }) 
    ] 
    }); 
    navigate.dispatch(resetAction); 
}

PermissionManager.js

import { PermissionsAndroid } from "react-native"; 

module.exports = { 
    requestSendSMSPermission: async function() { 
    try { 
     const granted = await PermissionsAndroid.request(
     PermissionsAndroid.PERMISSIONS.SEND_SMS 
    ); 
     if (granted === PermissionsAndroid.RESULTS.GRANTED) { 
     return true; 
     } else { 
     return false; 
     } 
    } catch (err) { 
     console.warn(err); 
    } 
    } 
};

这是我特意打电话_onPress方法

<RoundButton 
    textStyle={styles.roundTextStyle} 
    buttonStyle={styles.roundButtonStyle} 
    onPress={() => this._onPress()} 
    >

错误日志：

D:\React Native\application\node_modules\react-native\Libraries\ReactNative\YellowBox.js:76 Possible Unhandled Promise Rejection (id: 0): 
TypeError: Cannot read property 'receiptnumber' of undefined 
TypeError: Cannot read property 'receiptnumber' of undefined 
    at http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:106446:60 
    at tryCallOne (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:16011:12) 
    at http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:16097:15 
    at http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:7370:19 
    at _callTimer (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:7284:7) 
    at Object.callImmediatesPass (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:7512:9) 
    at Object.callImmediates (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:7523:21) 
    at MessageQueue.__callImmediates (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:6882:16) 
    at http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:6768:16 
    at MessageQueue.__guard (http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=true&minify=false:6868:9) 
console.warn @ D:\React Native\application\node_modules\react-native\Libraries\ReactNative\YellowBox.js:76 
onUnhandled @ D:\React Native\application\node_modules\react-native\Libraries\Promise.js:35 
onUnhandled @ D:\React Native\application\node_modules\promise\setimmediate\rejection-tracking.js:71 
(anonymous) @ D:\React Native\application\node_modules\react-native\Libraries\Core\Timers\JSTimers.js:223 
_callTimer @ D:\React Native\application\node_modules\react-native\Libraries\Core\Timers\JSTimers.js:143 
callTimers @ D:\React Native\application\node_modules\react-native\Libraries\Core\Timers\JSTimers.js:372 
__callFunction @ D:\React Native\application\node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:266 
(anonymous) @ D:\React Native\application\node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:103 
__guard @ D:\React Native\application\node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:231 
callFunctionReturnFlushedQueue @ D:\React Native\application\node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:102 
(anonymous) @ debuggerWorker.js:72

有谁知道我可以修复它？

它工作时，我删除Promise.resolve但我需要它的权限的东西。

_onPress() { 
    realm.write(() => { 
    realm.create("NewMessage", { 
     receiptNumber: this.state.receiptnumber, 
     text: this.state.text, 
     time: this.state.time 
    }); 
    }); 

    const resetAction = NavigationActions.reset({ 
    index: 0, 
    actions: [ 
     NavigationActions.navigate({ 
     routeName: "DashboardScreen" 
     }) 
    ] 
    }); 
    this.props.navigation.dispatch(resetAction); 
}

你可以尝试控制台登录this.state.receiptnumber渲染方法后立即解释一下吗？ –

如果它仍然未定义：尝试这样做添加componentWillMount方法，并把它放在这里面 this.setState（{receiptnumber：'your number' }）; –

@GaneshCauda是的。即使在'_onPress'中也可以访问。你可以请检查更新的问题。它不工作'Promise.resolve'，但我需要'Promise.resolve'权限 –

答

尝试更换

function(result)

到

result =>

我真的不能解释的理论，但基本上这个 '=>' 语法是抱着你的函数不会立即执行，

例如，如果你做这样的事情

onPress = {this.onPress}

是this.onPress方法会立即执行，即使没有新闻发布会

也许一些专家能够更恰当

你可以写为什么它不工作没有=> –

完成先生，也许我没有适当的解释，但那我现在知道这件事 –

类型错误：无法读取属性“receiptnumber”的未定义的反应本地

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