使用表单时发生错误:元素类型无效，应为字符串，但未定义 [英] Error when using a Form : Element type is invalid expected a string but got undefined

问题描述

我遇到以下错误

未捕获的不变变量:元素类型无效:预期a 字符串(对于内置组件)或类/函数(对于复合 组件)，但得到:未定义.您可能忘记了导出 文件中定义的组件

Uncaught Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in

我已经阅读了许多有关此错误的信息，例如此或此 但是他们都说相同:我错误地导出了我的组件.但是我不明白我的出口有什么问题

I have read many post about this error, like this or this but they all say the same : I incorrectly export my component. But I don't understand what is wrong with my export

import React, {Component} from 'react';
import {Platform, StyleSheet, Text, View, Image, ImageBackground, Linking, TouchableOpacity, TouchableHighlight, Alert, Button } from 'react-native';
import { createStackNavigator, createAppContainer } from "react-navigation";
import { FormLabel, FormInput, FormValidationMessage} from 'react-native-elements';

type Props = {};
export default class Login extends Component<Props> {
  constructor(props) {
    super(props);
    state = {
        login: '',
   };
  }
  someFunction(){
    Alert.alert("test")
  }

  onPress (){
    this.props.navigation.navigate('Home')
  }

  checkLogin(login){
    Alert.alert('test');
  }

  render() {
    return (
      <View style={styles.container}>
            <Image
              style={styles.image}
              source={require("./images/logo.png")}>
            </Image>
            <FormLabel style={styles.flex1}>enter Login of your Hotel</FormLabel>
            <FormInput 
                //value = {this.state.login}
                onChangeText={login => this.checkLogin({login})}
                //onChangeText={this.checkLogin.bind(login)}
                placeholder='enter your login'
                autoCapitalize = 'none'
                />
      </View>
    );
  }
}

和App.js:

import React, {Component} from 'react';
import {Platform, StyleSheet, Text, View, Image,ImageBackground, Linking, TouchableOpacity, Alert } from 'react-native';
import { createStackNavigator, createAppContainer } from "react-navigation"
import {HomeScreen} from './HomeScreen';
import Display from './Display';
import Login from './Login';

export default class App extends React.Component {
  render() {
    return <AppContainer />;
  }
}

const AppNavigator = createStackNavigator({
  Home: HomeScreen,
  Display: Display,
  Login: Login,
},
{
  initialRouteName: "Login",
  headerMode: 'none', 
}
);

const AppContainer = createAppContainer(AppNavigator);

您是否知道哪里出了问题?仅当我使用FormInput和FormLabel时才会出现错误.如果我替换为你好"，则会显示

Do you have an idea of what is wrong ? Error only comes when I use FormInput and FormLabel. If I replace by hello it is displayed

推荐答案

似乎在v1.0.0-beta中不推荐使用FormInput和FormLabel.

It seems that FormInput and FormLabel were deprecated in v1.0.0-beta.

请参阅此处(在 v1.0.0-beta(测试版1)更改部分下)-

See here (under v1.0.0-beta (beta 1) Changes section) - https://github.com/react-native-training/react-native-elements/releases/tag/v1.0.0-beta

您应该将Input而不是FormInput与label属性一起使用，而不是使用FormLabel组件.

You should use Input instead of FormInput with a label property instead of using FormLabel component.

<FormInput 
   label={"Login"} />

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