React Native : json.data is not a function. (In 'json.data()', 'json.data' is an instance of Array)]

user_13017720 0
Viewed 84

I'm trying to display data from my web using API. My API is working correctly. But some how i face this issue json.data is not a function. (In 'json.data()', 'json.data' is an instance of Array)]. Can I anyone help me on this? 

 _loadInitialState = async () => {

        const token = await AsyncStorage.getItem('token');
        const myArray = await AsyncStorage.getItem('language_type');
        _onSetLanguage(myArray)

        var loadAll = this.props.navigation.getParam('loadAll');
        if (loadAll == true) { this.setState({ isLoading: true }) }

        var have_access = this.props.navigation.getParam('have_access');
        if (have_access != undefined) { this.setState({ have_access: have_access }) }
        if (staticData.get_centre_settings() != null) { this.setState({ have_access: true }) }

        let today = Moment();
        this.setState({
            today: Moment(today).format('YYYY-MM-DD'),
        })

        // alert(FetchURL.get_baseURL() +  "leave?centre_id=" + staticData.get_centre_settings().centre.centre_id)
        // alert(token)
        // return
        fetch(FetchURL.get_baseURL() +  "leave?centre_id=" + staticData.get_centre_settings().centre.centre_id, {
            method: 'GET',
            headers: {
                'Authorization': 'Bearer '+ token,

            }
        })
        .then(response => response.json())
        .then((json) => {
            // alert(json)
            if (json.error) {
                alert(json.error);
            } else {
                this.setState({
                    staffLeave: json.data(),
                    isLoading: false
                });


            }

        })
        .catch((err) => {
            console.log(err)
            alert(err)
            // alert(strings.data_fail);
        })
    this.setState({ view_access: true })


    }

I kept searching for this but couldn't find an answer that will make this clear.

Thanks!

react-native arrays json javascript
3 Answers

You have the response after response.json() as json. If you want to store it to state, use json.data and not json.data(), just as you check for json.error.

user_129589260

When you read the error json.data is not a function. (In 'json.data()', 'json.data' is an instance of Array)]

What this is telling you is that json.data is not a callable function. Therefore json.data() will not work. json.data is an array per the error message. You would access some part of that by: json.data[0] But you'd want to check the length of that array and understand the type (which Typescript helps solve).

user_23047510 
// alert(json)
            if (json.error) {
                alert(json.error);
            } else {
                this.setState({
                    staffLeave: json.data(),
                    isLoading: false
                });


            }

Replace with

 if (json.error) {
                alert(json.error);
            } else {
                this.setState({
                    staffLeave: json.data,
                    isLoading: false
                });
            }

hopefully, it's work.

user_124839970
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