undefined不是評估_this.props.navigation React Native的對象

Question

我變得不確定，不是評估_this.props.navigation的對象。 這是我的代碼。

我想在多個屏幕中使用，因此我必須將其提取出來並在需要的地方調用它。

我已經嘗試https://github.com/react-navigation/react-navigation/issues/2198#issuecomment-316883535算不上運氣。

Category.js

import React, {Component} from 'react';
import {View, FlatList} from 'react-native';
import {ListItem} from 'react-native-elements'

import {AppRegistry, TouchableOpacity, ActivityIndicator} from 'react-native';
import {SearchHeader} from '../SearchHeader';

export default class Category extends Component {
  constructor() {
    super();
    this.state = {
      list: [],
    };
    this.onPress = this.onPress.bind(this);
  }

  static navigationOptions = {
    title: 'Categories',
    headerStyle: {backgroundColor: '#ffb30c'},
  };

  renderSeparator = () => {
    return (
      <View
        style={{
          height: 1,
          width: "98%",
          backgroundColor: "#CED0CE",
          marginLeft: "1%",
          marginRight: "1%"
        }}
      />
    );
  };

  _keyExtractor = (item, index) => item.name;

  renderHeader = () => {
    return (<SearchHeader />);
  };

  renderFooter = () => {
    if (!this.state.loading) return null;

    return (
      <View
        style={{
          paddingVertical: 20,
          borderTopWidth: 1,
          borderColor: "#CED0CE"
        }}
      >
        <ActivityIndicator animating size="large"/>
      </View>
    );
  };

  onPress = (item) => {
    this.props.navigation.navigate('SpecTypeScreen',{cat:item});
  };

  search = () => {
  };

  render() {
    return (
      <FlatList
        data={this.state.list}
        renderItem={({item}) => (
          <TouchableOpacity onPress={() => this.onPress(item)}>
            <ListItem
              title={`${item.name}`}
              containerStyle={{borderBottomWidth: 0}}

            />
          </TouchableOpacity>
        )}
        keyExtractor={this._keyExtractor}
        ItemSeparatorComponent={this.renderSeparator}
        ListHeaderComponent={this.renderHeader}
        ListFooterComponent={this.renderFooter}
      />
    );
  }
}

AppRegistry.registerComponent('CategoryScreen', () => CategoryScreen);

SearchHeader.js

import React, {Component} from 'react';
import Autocomplete from 'react-native-autocomplete-input';
import {
  AppRegistry,
  View,
  StyleSheet,
  Platform,
  Text,
  TouchableOpacity,
} from 'react-native';
import {withNavigation} from 'react-navigation';
import colors from './config/colors';
import normalize from './config/normalizeText';

export class SearchHeader extends Component {
  constructor() {
    super();
    this.state = {
      list: [],
    };
  }

  search = (term) => {
    if (term.length > 2) {
      fetch("https://myUrl?term=" + encodeURI(term))
        .then((response) => response.json())
        .then((responseJson) => {
          this.setState({list: responseJson});
          console.log(responseJson);
        })
        .catch((error) => {
          console.error(error)
        });
    }
    else{
      this.setState({list: []});
    }
  };
  onPress = (item) => {
    this.props.navigation.navigate('ProductScreen',{spec:item});
  };
  render() {
    return (
      <View style={[
        styles.container, styles.containerLight
      ]}>
        <Autocomplete placeholder="Search Specs & Approvals..."
                      autoCorrect={false}
                      onChangeText={this.search}
                      data={this.state.list}
                      containerStyle={{backgroundColor: "#d71201"}}
                      inputStyle={{backgroundColor: "#fff"}}
                      renderItem={({ id, specification }) => (
                        <TouchableOpacity style={styles.autocompleteContainer} onPress={this.onPress.bind(this, specification)}>
                          <Text style={styles.itemText}>
                            {specification}
                          </Text>
                          <View
                            style={{
                              height: 1,
                              width: "98%",
                              backgroundColor: "#CED0CE",
                              marginLeft: "1%",
                              marginRight: "1%"
                            }}
                          />
                        </TouchableOpacity>
                      )}
                      style={[
                        styles.input,
                        styles.inputLight,
                        {borderRadius: Platform.OS === 'ios' ? 15 : 20},
                        {paddingRight: 50}
                      ]}/>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    borderTopWidth: 1,
    borderBottomWidth: 1,
    borderBottomColor: '#000',
    borderTopColor: '#000',
    backgroundColor: "#d71201",
    maxHeight:70
  },
  containerLight: {
    borderTopColor: '#e1e1e1',
    borderBottomColor: '#e1e1e1',
  },
  input: {
    paddingLeft: 26,
    paddingRight: 19,
    margin: 8,
    borderRadius: 3,
    overflow: 'hidden',
    backgroundColor: colors.grey5,
    fontSize: normalize(14),
    color: colors.grey3,
    height: 40,
    ...Platform.select({
      ios: {
        height: 30,
      },
      android: {
        borderWidth: 0,
      },
    }),
  },
  inputLight: {
    backgroundColor: "#fff"
  },
  autocompleteContainer: {
    backgroundColor:"#fff",
    marginLeft: 10,
    marginRight: 10
  },
  itemText: {
    fontSize: 15,
    margin: 5,
    marginLeft: 20,
    paddingTop:5,
    paddingBottom:5
  },
  descriptionContainer: {
    backgroundColor: '#F5FCFF',
    marginTop: 8
  },
  infoText: {
    textAlign: 'center'
  },
  titleText: {
    fontSize: 18,
    fontWeight: '500',
    marginBottom: 10,
    marginTop: 10,
    textAlign: 'center'
  },
  directorText: {
    color: 'grey',
    fontSize: 12,
    marginBottom: 10,
    textAlign: 'center'
  },
  openingText: {
    textAlign: 'center'
  }
});

AppRegistry.registerComponent('SearchHeader', () => SearchHeader);

Answer 1

您需要向下傳遞navigation道具。 嘗試這個：

renderHeader = () => {
   return (<SearchHeader navigation={this.props.navigation} />);
};

Answer 2

您需要使用withNavigation(Component)包裝您的組件

示例： AppRegistry.registerComponent('SearchHeader', () => withNavigation(SearchHeader));

withNavigation的要點是，您不需要將導航作為道具。 當您穿越多個孩子時特別有用。