(React-Native)未定义不是对象(评估_'this.props.navigation.navigate')
我对 React 还是个新手。我想让我的登录按钮在按下时创建一个新屏幕。我尝试了多次,但似乎无法解决此错误:
我做错了什么?
LoginForm.js:
import React, { Component } from 'react';
import { TextInput, Text, View, StyleSheet, TouchableOpacity } from 'react-native';
import { StackNavigator } from 'react-navigation';
import { Button, CardSection, Input, Spinner } from './common';
import Account from './screens/Account';
import SignUpForm from './SignUpForm';
class LoginForm extends Component {
render() {
return (
<View style={styles.container}>
<TextInput
placeholder="Username or email"
placeholderTextColor='white'
returnKeyType='next'
style={styles.input}
keyboardType="email-address"
onSubmitEditing={() => this.passwordInput.focus()}
/>
<TextInput
secureTextEntry //turns text into *** good for passwords
label="Password"
placeholder="password"
placeholderTextColor='white'
secureTextEntry
returnKeyType='go'
style={styles.input}
ref={(input) => this.passwordInput = input}
/>
<TouchableOpacity style={styles.buttonContainer}>
<Text style={styles.buttonText}>LOGIN</Text>
</TouchableOpacity>
<Text style={styles.textStyle}> Need help logging in?{'\n'}
or
</Text>
<View style={styles.divider} />
<TouchableOpacity
style={styles.buttonContainer}
onPress={() => this.props.navigation.navigate('SignUpForm')}
>
<Text style={styles.buttonText}>Sign Up</Text>
</TouchableOpacity>
</View>
);
}
}
export default LoginForm;
**Account.js:**
import React from 'react';
import { View, Image, TouchableOpacity, Text, TextInput } from 'react-native';
import { StackNavigator } from 'react-navigation';
import { Card, Button, Spinner, CardSection } from '../common';
import LoginForm from '../LoginForm';
class Account extends React.Component {
static navigationOptions = {
tabBarLabel: 'Account'
}
render() {
return (<View style={styles.containerStyle}>
<Card>
<View style={styles.logoContainer}>
<Image style={styles.logo} source= .
{require('../../Images/ShoeJackCityLogo.png')}/>
</View>
<View style={styles.formContainer}>
<LoginForm />
</View>
</Card>
</View>);
}
}
export default Account;
**SignUpForm.js:**
import React, { Component } from 'react';
import { TextInput, Text, View, StyleSheet, TouchableOpacity } from 'react-native';
import { Button, CardSection, Input, Spinner } from './common';
import router from '../../config/router';
class SignUpForm extends Component {
render() {
return (
<View style={styles.container}>
<TextInput
placeholder="Username or email"
placeholderTextColor='white'
returnKeyType='next'
style={styles.input}
keyboardType="email-address"
onSubmitEditing={() => this.EmailInput.focus()}
/>
<TextInput
placeholder="Email"
placeholderTextColor='white'
returnKeyType='next'
style={styles.input}
keyboardType="email-address"
onSubmitEditing={() => this.passwordInput.focus()}
/>
<TextInput
secureTextEntry //turns text into *** good for passwords
label="Password"
placeholder="password"
placeholderTextColor='white'
secureTextEntry
returnKeyType='go'
style={styles.input}
ref={(input) => this.passwordInput = input}
/>
<TouchableOpacity style={styles.buttonContainer}>
<Text style={styles.buttonText}>Register</Text>
</TouchableOpacity>
</View>
);
}
}
export default SignUp;
import React from 'react';
import { TabNavigator, StackNavigator } from 'react-navigation';
import { Icon } from 'react-native-elements';
**Router.js**
import Tournaments from '../components/screens/Tournaments';
import Account from '../components/screens/Account';
import Artists from '../components/screens/Artists';
import Shop from '../components/screens/Shop';
import SignUpForm from '../components/SignUpForm';
export const AccountStack = StackNavigator({
Account: {
screen: Account,
navigationOptions: {
title: 'Account',
headerBackTitle: null,
},
SignUpForm: {
screen: SignUpForm,
navigationOptions: {
title: 'Register'
}
},
忽略此:jsksjkjdkfjkdfkjkdjskfjskjfjksjkjfkjsjfkjskfsjfjsjfksjfjfskfjkskjfjkjskjfjjksfjkfjkfjssfjkfksskjfjsfjk
<LoginForm />
我没有看到您将任何 props 传递到 LoginForm 中,该属性在 onPress 中需要 this.props.navigation。
我认为您对
react-native
中的导航堆栈的工作方式有些困惑。因此,本质上有两种导航到屏幕的方式。
-
通过在
StackNavigator
类中声明它,您将为<LoginForm/>
组件提供所需的导航对象。一旦声明,您将需要从任何屏幕导航到登录表单 - 例如 -this.props.navigation.navigate('LoginForm')
。 注意 - 您只能从<Account/>
或<Signup/>
导航,因为这两个屏幕当前在其范围内拥有导航对象。现在,一旦您导航到登录表单组件,您基本上就会在范围内拥有导航对象,并且您的undefined
错误将消失。 -
如果您决定不在
StackNavigator
类中声明<LoginForm/>
屏幕,则需要将navigation
对象明确作为 props 传递给组件,例如 -<LoginForm navigation={this.props.navigation} />
。因此,无论何时呈现此组件,您都可以以与使用相同的方式获取导航 prop。
希望它能为您清除一切 :)
如果没有看到您声明 stafcknavigation 的位置,我很难判断,如果没有,则此链接可了解如何 http://react-navigation%20stack%20navigator%20custom%20header
否则,您可能没有将导航方法传递给嵌套组件 这里有一个链接可以查看如何执行此操作 在 React Native 中在组件之间导航