TypeError: undefined is not an object (evaluating 'routes[index].params.theme')

Question

老师这个怎么解决

Answer 1

CrazyCodeBoy 2018-07-09 09:57:49

确认下react-navigation的版本如果是2.0以上版本参考如下代码：

import {createDrawerNavigator, createStackNavigator,SafeAreaView,DrawerItems} from 'react-navigation';
import {createBottomTabNavigator, BottomTabBar} from 'react-navigation-tabs';

class TabBarComponent extends React.Component {
    constructor(props) {
        super(props);
        this.theme = {
            tintColor: props.activeTintColor,
            updateTime: new Date().getTime()
        }
    }

    render() {
        const {routes, index} = this.props.navigation.state;
        const {theme} = routes[index].params;
        if (theme && theme.updateTime > this.theme.updateTime) {
            this.theme = theme;
        }
        /**
         * custom tabBarComponent
         * https://github.com/react-navigation/react-navigation/issues/4297
         */
        return (
            <BottomTabBar
                {...this.props}
                activeTintColor={this.theme.tintColor || this.props.activeTintColor}
            />
        );
    }

}

export const AppTabNavigator = createBottomTabNavigator({
    Page1: {
    ...

Answer 2

r4ggjlx 2018-07-07 23:59:03

routes[index].params ===undefined?

• 提问者 liuxiaozhu #1

  想知道根本原因，routes[index] 跟 theme 到底是哪里来的？课程里根本没有提到。

• CrazyCodeBoy 回复 提问者 liuxiaozhu #2

  theme 在Page1中有介绍：
  
  <Button
                  title="改变主题色"
                  onPress={() => {
                      navigation.setParams({theme:{
                          tintColor:'orange',
                          updateTime:new Date().getTime()
                      }})
                  }}
              />

• 提问者 liuxiaozhu 回复 CrazyCodeBoy #3

  第一次加载的时候，确实是 undefined。我想知道第一次加载时，在哪里配置传入这个 params ？