How To Build WordPress Client App with React Native Part #11: Remove Bookmark Feature

Here, we are going to implement the removing of the bookmark from the articles. This case is simpler than saving the bookmarks. Here, we are going to define a function called removeBookMark. For that, we need to use the code from the following code snippet:

removeBookMark = async post_id => {
    this.setState({already_bookmark: false});
    const bookmark = await AsyncStorage.getItem('bookmark').then(token => {
      const res = JSON.parse(token);
      return res.filter(e => e !== post_id);
    });
    await AsyncStorage.setItem('bookmark', JSON.stringify(bookmark));
  };

Here, we have changed the state of 

already_bookmark

Render Bookmark

Here, we are going to change the value of the 

already_bookmark

already_bookmark

SinglePost

renderBookMark = async post_id => {
    await AsyncStorage.getItem('bookmark').then(token => {
      const res = JSON.parse(token);
      let data = res.find(value => value === post_id);
      return data == null
        ? this.setState({already_bookmark: false})
        : this.setState({already_bookmark: true});
    });
  };

Here, the function takes post id as a parameter. Then, by using the post id, we get the bookmark ids using the getItem function of AsyncStorage. After we get the values, we parse it and then check if the articles post id is present in the bookmark array or not. If present, we set the

already_bookmark 

Then, we need to call this function on componentDidMount() and set post id as a parameter which we get from the navigation props as shown in the code snippet below:

componentDidMount() {
    this.fetchPost().then(()=>{
       this.renderBookMark(this.props.navigation.getParam('post_id'));
    });
   
  }

Hence, we will get the following result in the emulator screens:

As we can see, we have successfully implemented the bookmark feature in the SinglePost screen. Now, we are able to bookmark the articles. But, we need to show the bookmarked post somewhere as well. We are going to do that in the Bookmark screen in the Bookmark.js file.

Bookmark index screen

Here, we are going to implement the Bookmark Screen to display all the bookmarked articles. We have already set up the navigation to Bookmark screen in our bottom tab navigator. Hence, we can see the Bookmarks in the emulator screens below:

ere, we are going to show the posts which are going to be similar to that of the Home Screen. We are going to fetch the bookmarked posts from the server and display them as a list.

But first, we need to define new state variables called bookmark_post and isFetching. The bookmark_post will store the bookmarked post that we fetch from the server. And, the isFetching state is for showing the loader. They are defined as shown in the code snippet below:

class Bookmark extends Component {
  constructor(props) {
    super(props);
    this.state = {
      bookmark_post: [],
      isFetching: false,
    };
  }

Then, we need to import the AsyncStorage package in the Bookmark.js file as shown in the code snippet below:

import AsyncStorage from '@react-native-community/async-storage';

Then, we need to fetch the bookmarked posts from the server. For that, we need to define a new function called 

fetchBookMark

async fetchBookMark() {
    let bookmark = await AsyncStorage.getItem('bookmark').then(token => {
      const res = JSON.parse(token);
      if (res != null) {
        const result = res.map(post_id => {
          return 'include[]=' + post_id;
        });
        return result.join('&');
      } else {
        return null;
      }
    });
    const response = await fetch(
      `https://kriss.io/wp-json/wp/v2/posts?${bookmark}`
    );
    const post = await response.json();
    //this.setState({ posts: post });
    this.setState({ bookmark_post: post });
  }

Here first, we get the bookmark data from AsyncStorage then we map all post id to build query string match on WordPress API. Then, we request to WordPress API using fetch function and get the response of the bookmarked post. We parse the response as JSON and then set it to the 

bookmark_post

Next, we are going to use the 

FlatList

componentDidMount() {
    
      this.fetchBookmark();
   
  }
render() {
    return (
      <View>
        <Headline style={{marginLeft: 30}}>Bookmark Post</Headline>
        <FlatList
          data={this.state.bookmark_post}
          renderItem={({item}) => (
            <TouchableOpacity
              onPress={() =>
                this.props.navigation.navigate('SinglePost', {
                  post_id: item.id,
                })
              }>
              <Card
                style={{
                  shadowOffset: {width: 5, height: 5},
                  width: '90%',
                  borderRadius: 12,
                  alignSelf: 'center',
                  marginBottom: 10,
                }}>
                <Card.Content>
                  <Title>{item.title.rendered}</Title>
                  <Paragraph>
                    Published on {moment(item.date).fromNow()}
                  </Paragraph>
                </Card.Content>
                <Card.Cover source={{uri: item.jetpack_featured_media_url}} />
                <Card.Content>
                  <Card.Content>
                    <HTMLRender html={item.excerpt.rendered} />
                  </Card.Content>
                </Card.Content>
              </Card>
            </TouchableOpacity>
          )}
          keyExtractor={item => item.id}
        />
      </View>
    );
  }
}

We need to remember to make the imports just as in the Home screen. And, we need to call the fetch function in the componentDidMount hook.

Hence, we will get the following result in the emulator screen:

Here, we have got the bookmarked post list on the Bookmark screen. But, when we switch tab, we will see that the componentDidMount doesn’t fire. This not good because the bookmark can update every time. Without refreshing the Bookmark screen, the bookmark posts won’t update.

So, after brainstorming through this issue, we can get the solution in StackOverflow. It recommends triggering didFocusevent then by update class. Now, we are going to make configuration as in the documentation. First, we need to make the following import:

import {withNavigationFocus} from 'react-navigation';
class Bookmark extends Component {

Here, we imported withNavigationFocus from the react-navigation. Then, we need to move export default to bottom with inside the withNavigationFocus function as shown in the code snippet below:

export default withNavigationFocus(Bookmark);

And, for the listener event, we are going to use it in the

componentDidMount 

componentDidMount() {
    const {navigation} = this.props;
    this.focusListener = navigation.addListener('didFocus', () => {
      this.fetchBookmark();
    });
    
  }

Hence, we will get the following result in the emulator screens:

As we can see, now the Bookmark screen fetches the bookmarks every time we navigate to it.

Summary

In this chapter, we learned how to remove and render the bookmark. Then, making use of the AsyncStorage and fetch method, we successfully fetched the bookmarked post to be displayed on the Bookmark screen. Lastly, we learned how to re-fetch the bookmarked post every time we enter the Bookmark screen so that new bookmarks show up.

This series intends to show how I build an app to serve content from my WordPress blog by using react-native. Since my blog is talking about react-native, the series and the articles are interconnected. We will learn how to set-up many packages that make our lives comfortable and learn how to deal with WordPress APIs. Here, the most prominent features talked about in the book are the dark theme, offline mode, infinite scroll and many more. You can discover much more in this series. this inspiration to do this tutorial series came from the React Native App Templates from instamobile