Why I cant set value to my states? REAECT-NATIVE

Question

im new in react-native, im passing data by navigation to my edit_note screen, once i received i set it to my states, but it doesnt work, if i print them, it shows their values, but setting to my states doesnt work, heres the code:

heres the Notes class, in the navigation function im passing the datas, data and note_number to Edit_note

render() {
    return (
        <>
        <View style = {this.styles.View}>
           <FlatList data = {this.props.data} renderItem = {({item}) => (<TouchableOpacity onPress = {() => this.props.navigation.navigate("Edit_note", {data: this.props.data, note_number: item.note_number})}><Text style = {this.styles.Text}>{item.title}</Text></TouchableOpacity>)} keyExtractor = {(item) => item.note_number.toString()}></FlatList>
        </View>
        </>
    );
}

in Edit_note im receiving it like this:

    class Edit_note extends Component {

    constructor() {
        super();
        this.state = {
            array_notes: [],
            note_number: "",
        }
    }
    componentDidMount() {
        const {params} = this.props.navigation.state;
        let x = params.note_number;
        this.setState({note_number: x});
        console.log(this.state.note_number);
    }
    render() {
        return (
           <Text></Text>
        );
    }
}

if i print x, it will print the note_number, but setting it into note_number, and print it, it doesnt show anything, why?

Does this answer your question? [Why calling react setState method doesn't mutate the state immediately?](https://stackoverflow.com/questions/30782948/why-calling-react-setstate-method-doesnt-mutate-the-state-immediately) — glinda93, Aug 09 '20 at 08:16

score 0 · Answer 1 · answered Aug 09 '20 at 08:08

0

You actually set it but your console.log() fires before the change.

After a state changes component rerenders so you can try printing it on screen like;

render() {
    return (
       <Text>{this.state.note_number}</Text>
    );
}

answered Aug 09 '20 at 08:08

Cappydh

26
1
6

score 0 · Answer 2 · answered Aug 09 '20 at 08:09

0

setState is asynchronous that means that the state indeed changes but the console.log right after the setState is not showing the change.

You can learn more about it here.

answered Aug 09 '20 at 08:09

D10S

1,468
2
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Why I cant set value to my states? REAECT-NATIVE

2 Answers2