Question

我正在开发一个简单的React Native iOS应用程序，只是为了学习React Native，这是我的第一个React Native应用程序。现在，我正在练习使用ListView。但是似乎项目已加载到列表视图中，但未显示数据。

这是我的减速器

import * as AlbumListActions from '../actions/AlbumListActions';

const defaultState = {
    albums: [ ],
    loading: false,
    message: null
}

export default albumListReducer = (state = defaultState, action) => {
    switch (action.type) {
        case AlbumListActions.ALBUMS_START_FETCHING_ALBUMS:
            return { ...state, loading: true, albums: [ ] }
            break;

        case AlbumListActions.ALBUMS_COMPLETE_FETCHING_ALBUMS:
            return { ...state, loading: false, albums: action.payload }
            break;

        case AlbumListActions.ALBUMS_CATCH_FETCHING_ALBUMS:
            return { ...state, loading: false, message: action.payload }
            break;

        default:
            return { ...state };
    }
}

这是我的动作

import Axios from 'axios';

export const ALBUMS_START_FETCHING_ALBUMS = "(albums) start fetching albums";
export const ALBUMS_COMPLETE_FETCHING_ALBUMS = "(albums) complete fetching albums";
export const ALBUMS_CATCH_FETCHING_ALBUMS = "(albums) catch fetching albums";

export const completeFetchingAlbums = (data) => {
    return {
        type: ALBUMS_COMPLETE_FETCHING_ALBUMS,
        payload: data
    }
}

export const catchFetchingAlbums = (data) => {
    return {
        type : ALBUMS_CATCH_FETCHING_ALBUMS,
        payload: data
    }
}

export const fetchAlbums = (data) => {
    return (dispatch) => {
        dispatch({
            type: ALBUMS_START_FETCHING_ALBUMS
        });

        return Axios.get("http://rallycoding.herokuapp.com/api/music_albums").then((response) => {
            dispatch(completeFetchingAlbums(response.data));
        }).catch((error) => {
            dispatch(catchFetchingAlbums("Unable to fetch data from the server"));
        })
    }
}

这是我的组件渲染列表视图。

class AlbumList extends React.Component {
    componentWillMount() {
        this.props.fetchAlbums();
    }

    renderAlbumItem = (album) => {
        return (
                <View style={styles.container}>
                    <Text>{album.title}</Text>
                </View>
            )
    }

    render() {
        return (
            <View>
            <FlatList
                data={this.props.albums}
                renderItem={this.renderAlbumItem}
                keyExtractor={(album) => album.title}
            />
            </View>
        )
    }
}

const mapStateToProps = state => {
    return state.albumList;
}

const mapDispatchToProps = (dispatch, ownProps) => {
    return bindActionCreators({
        fetchAlbums : AlbumListActions.fetchAlbums
    }, dispatch)
}

export default connect(mapStateToProps, mapDispatchToProps)(AlbumList);

运行我的应用程序时，它没有显示任何内容。有什么问题，我该如何解决？

Answer 1

renderItem的签名是错误的。它接受一个对象，其属性之一是item，其中包含您要渲染的相册。

要使其正常运行，请按以下方式更改renderItem：

renderAlbumItem({item}) => {
    return (
            <View style={styles.container}>
                <Text>{item.title}</Text>
            </View>
        )
}

您还可以将item重命名为album-renderAlbumItem({item: album})。这种语法称为对象解构，您可以在Google上进行解释。在这种情况下，请使用{album.title}访问标题。

React Native列表视图未显示数据

1 个答案: