CODEWITHSUNDEEP
javascriptjsonnode.jspromise
Mike Risher
Mike Risher

Reputation: 35

Handling an empty array with the error "Uncaught (in promise) SyntaxError: Unexpected end of JSON input."

I have a react / redux / node express app that manages patient information. I have a bug with reading new data after I've deleted a patient encounter. The functions work fine until I delete the last encounter associated with the patient. Then there's an error: "Uncaught (in promise) SyntaxError: Unexpected end of JSON input."

To get around having no data passed along, I've tried to check if a 204 status comes back (no content) and I create an empty array and send that along as my JSON response instead of no data. This hasn't fixed the error.

How can I handle the lack of content without an error being raised in the console? Instead of returning [ ] (empty array) I've also tried returning ' [ ] ' (empty array with single quotes around it) (which I thought was valid JSON), but no luck.

readPatientEncounters(id) {
    let url = '/encounters/findPatient/'+id;
    Data.readData(url,(response) => {
        if (response.length !== 0) {
            response.sort(function (a, b) {
                return a.date-b.date;
            });
        }
        this.props.dispatch(EncountersActions.readEncounters(response));
    }, (errorMessage) => {
        console.log('having an error>',errorMessage);
    });
}

class Data {
    static readData(path, onSuccess, onFailure) {
        let headers = new Headers({ 'Content-Type': 'application/json',
            'x-access-token': sessionStorage.getItem('jwt') });
        let myInit = {
            'method': 'GET',
            'headers': headers
        };
        let url = config.server_url + path;
        fetch(url, myInit).then(response => {
            var jsonResponse = response.json();
            if (response.status === 204) {
                return [];
            } else {
                return jsonResponse;
            }
        }).then(jsonResponse => {
            onSuccess(jsonResponse);
            return;
        }).catch(errorMessage => {
            onFailure(errorMessage);
            return errorMessage;
        });
    }
}

Upvotes: 0

Views: 910

Answers (1)

Mike Risher
Mike Risher

Reputation: 35

The solution was provided by jaromanda-x (https://stackoverflow.com/users/5053002/jaromanda-x)

This code was converting to JSON format regardless of the response:

 var jsonResponse = response.json();
    if (response.status === 204) {
        return [];
    } else {
        return jsonResponse;
    }

This solved this issue:

if (response.status === 204) {
    return [];
} else {
    return response.json();
}

Upvotes: 2

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