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[英]React Native: React Navigation StackNavigator not working. Getting error: “undefined is not an object (evaluating 'this.props.navigation.navigate')”
[英]React Native Navigation(StackNavigator): I get an error saying “ undefined is not an object (evaluating 'this.props.navigate') ”
我才剛剛開始學習本機操作。...現在正在做一個寵物項目。...在應用程序中,單擊它時有一個按鈕導航到另一個屏幕。 我收到以下錯誤消息:“ undefined不是對象(正在評估'this.props.navigate')”以下是文件
index.js
import React from "react";
import Navigator from "./config/routes";
export default () => <Navigator />;
我的config / routes.js中的代碼
import { StackNavigator } from "react-navigation";
import Home from "../screens/Home";
import List from "../screens/List";
export default StackNavigator({
Home: {
screen: Home,
navigationOptions: {
header: () => null
}
},
List: {
screen: List
}
});
和我的組件文件Home.js,該文件具有單擊后單擊導航到另一個屏幕的按鈕
/*all import statements*/
class Home extends Component {
handlePressBaseCurrency() {
console.log("base currency button clicked");
this.props.navigation.navigate("List"); /* error from this line */
}
render() {
return (
<UserInput
currencyShort={TEMP_BASE_CURRENCY}
onPress={this.handlePressBaseCurrency}
defaultValue={TEMP_BASE_PRICE}
keyboardType="numeric"
onChangeText={this.handleTextChange}
/>
);
}
}
請幫忙!!! 提前致謝
this
在handlePressBaseCurrency
未正確handlePressBaseCurrency
。 您可以:
在您的構造函數中明確綁定 this
:
constructor(props) { super(props); this.handlePressBaseCurrency = this.handlePressBaseCurrency.bind(this); }
從React Docs 處理事件 :
如果使綁定煩惱,可以通過兩種方法解決此問題。 如果使用實驗性的公共類字段語法 ,則可以使用類字段正確綁定回調:
handlePressBaseCurrency = () => { console.log("base currency button clicked"); this.props.navigation.navigate("List"); };
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