Getting values from nested JSON document

Question

I'm trying to get values from a nested JSON document. I wrote the following function:

var jsondata = {
'name': {
    'fname': 'Jack',
    'lname': [{'familyName': 'Sparrow'}, {'surname': 'Captain'}]
    }
};

var extracted = get_value(jsondata, 'familyName');
console.log(extracted); // null is getting printed

function get_value(dataObject, keyName) {
    value = null;

    for (var i in dataObject) {
        if (i == keyName) {
            value = dataObject[keyName];
            console.log(value); // getting correct value of 'familyName' here
            return value;
        } else if (typeof dataObject[i] == 'object') {
        get_value(dataObject[i], keyName);
        }
    }
    return value;
}

The problem is, I'm getting the correct value when printing console.log(value);, but null is getting printed by console.log(extracted);. Its like a return inside the for-in loop is not actually exiting the loop when the value is found.

What am I doing wrong? Thanks in advance.

I think it should be name.lname.familyname try it out once. @Sparky — Kira
– Kira, Commented Aug 19, 2013 at 10:27
Thanks @Kira, that kind of access will work, but I was trying more of a dynamic approach. — Sparky
– Sparky, Commented Aug 19, 2013 at 10:35

Craig · Accepted Answer · 2013-08-19 10:25:46Z

1

In your function you need to assign the value returned by get_value:

get_value(dataObject[i], keyName);

Should be:

value = get_value(dataObject[i], keyName);

Alternatively, just return the value:

return get_value(dataObject[i], keyName);

answered Aug 19, 2013 at 10:25

Craig

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1 Comment

Sparky Over a year ago

Aah, that worked with the initial problem. But failed to work when I tried get_value(jsondata, 'surname'); instead of get_value(jsondata, 'familyName');

Sparky · Accepted Answer · 2013-08-19 12:08:42Z

1

Finally I rewrote the code and now it will return the value of any given key in the json data:-

function get_value_nested(dataObject, keyName) {
    var value = null;
    this.get_value = function (dataObject, keyName) {
        for (i in dataObject) {
            if (i == keyName) {
                value = dataObject[keyName];
            } else if (typeof dataObject[i] == 'object') {
                 this.get_value(dataObject[i], keyName);
            }
        }
        return value;
    }

    this.get_value(dataObject, keyName);

    return value;
}

answered Aug 19, 2013 at 12:08

Sparky

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Comments

Andy · Accepted Answer · 2013-08-19 10:37:45Z

0

Remove value = null; from the function.

answered Aug 19, 2013 at 10:37

Andy

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1 Comment

Sparky Over a year ago

Then it will give undefined :)

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