Turn a json object string into value

Question

I am writing a function that takes a string, splits it, and the uses json[key][key2][key3] formatting. The problem is n is potentially infinite (not literally but needs to written that way)

function getJsonValue(json,string) {
    var vals = string.split(".");
    var x = vals.length;
    var string = '';
    while (x != 0) {
      string += "['"+vals[(vals.length-x)]+"']"
        x--
    }
    return string;
}

That will produce, for example: "['condition']['item']['condition']['temp']"

I need to extract a value from that by attaching it to a json object, like

json"['condition']['item']['condition']['temp']"

But I don't know how or if that is even possible.

Edit: The problem is I need any value from a config file to be passed in and then parsed from a returning function. I.e. User knows the value will be condition.item.condition.temp for this specific query. I am trying to write one function that covers everything and pass in config values for what I know to be the output. So, on one query, I might want the condition.item.condition.temp value and on another I might want condition.wind.chill .

Are you outputting this value to another JavaScript file? If not, I don't believe this current implementation will work. ETA: One possible solution for this is if you generate the string and wish to inject it into a 'script' element in your project using jQuery but that's not elegant. — Mike
– Mike, Commented Jan 7, 2016 at 22:05
So what is the problem exactly? Is this code not working? Isn't the output what you want? You can also use this notation : json.key1.key2.key3 — Jeremy Thille
– Jeremy Thille, Commented Jan 7, 2016 at 22:07
No, just trying to attach it to an object. I am toying with some other ways to accomplish the task but similar manner, just not using strings. — Mitchell Ingram
– Mitchell Ingram, Commented Jan 7, 2016 at 22:08

Alex Santos · Accepted Answer · 2016-01-07 22:10:50Z

2

I'm not sure if I understand 100% what you're trying to do, but if you're receiving a JS object json and a string in the format field1.field2.field3 and trying to get the value of json.field1.field2.field3 then you can do something like this:

function getJsonValue(json,string) {
    var vals = string.split(".");
    for (var i = 0; i < vals.length; i++) json = json[vals[i]];
    return json;
}

It would work like this for a given object:

var obj = { field1: { field2: { field3: "Hello!" } } };
var res = getJsonValue(obj, "field1.field2.field3"); 
console.log(res); // prints Hello

answered Jan 7, 2016 at 22:10

Alex Santos

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3 Comments

Mitchell Ingram Over a year ago

I tried that earlier, and it kept hanging. No clue why.

Alex Santos Over a year ago

It's not doing any input validation, if you want to share an input sample I can test here. It should work for the example I've sent, but if you give a set of fields that don't exist in the object, it will throw an error although you can easily fix that.

Mitchell Ingram Over a year ago

Yeah, I am not really sure why it isn't working right now. But I am going to mark this the answer because it has to be.

Sylvain · Accepted Answer · 2016-01-07 22:11:23Z

0

See lodash get

_.get(json, 'key1.key2.key3')

you can build the "path" from your current code and ask lodahs to get the value out for you.

answered Jan 7, 2016 at 22:11

Sylvain

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Comments

Rajan Panneer Selvam · Accepted Answer · 2016-01-07 22:13:38Z

0

What about doing an eval?

var json = {
    'one': {
        'two': {
            'three': {
                'four': 4
            }
        }
    }
};

alert(eval("json['one']['two']['three']['four']"))

answered Jan 7, 2016 at 22:13

Rajan Panneer Selvam

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