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how to parse JSON

Hi,

I have a sample code getting xml output from a http request.

If the call is successful, it calls this :

                if(xhr.status === 200) {
                    success && success(xhr.responseText);
                }

And it  goes to :

    var _requestJson = function(method, url, data, success, failure) {
        var _success = function(data) {
            try {
                data = JSON.parse(data);
            }
            catch(e) {
                failure && failure({ type: 'json', message: e.message });
                return;
            }

            success && success(data);
        };

        if(data !== null) {
            try {
                data = JSON.stringify(data);
            }
            catch(e) {
                failure && failure({ type: 'json', message: e.message });
                return false;
            }
        }

        return _request(method, url, data, _success, failure);
    };

now , how can I get the parsed data ?

I know this seems like a noob question but I really don't understand this JSON structure and I need to do it quickly for helping a friend. I'd appreciate if anyone could give me an assist.

 

Thanks.

 

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19 Replies
Sanjeev BA

No problem.

You need to know the structure of the json document and extract values based on the keys you are looking for.

https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse

Numerous stackoverflow examples are available.

AVSukhov

Hello,

To see the structure of your json data, just enter the data into the console:

console.log(data)

After this you can manipulate this using key/value

data.key or data[key]

Marco Buettner 
console.log(data);

will just only show [object Object] ...

console.log(JSON.stringify(data));

will show {"key":"value"}

AVSukhov

OK =)) You are right.

colin Rao

JSON, JavaScript Object Notation. It's simple and easy to use. 

Format: {key:value}, the key can be a simple string name, the the value can be a number, string, boolean, array/list, object, null.

the key/value are separate by ":", multiple key/value pair as separate by ",".

Example:

var people = {
"programmers":[{"firstName":"Brett","lastName":"McLaughlin","email":"aaaa"},
{"firstName":"Jason","lastName":"Hunter","email":"bbbb"},
{"firstName":"Elliotte","lastName":"Harold","email":"cccc"}
],
"authors":[{"firstName":"Isaac","lastName":"Asimov","genre":"sciencefiction"},
{"firstName":"Tad","lastName":"Williams","genre":"fantasy"},
{"firstName":"Frank","lastName":"Peretti","genre":"christianfiction"}
],
"musicians":[{"firstName":"Eric","lastName":"Clapton","instrument":"guitar"},
{"firstName":"Sergei","lastName":"Rachmaninoff","instrument":"piano"}
]
};

Read/Write Value:

var lastname = people.programmers[0].lastName;

people.programmers[0].lastName = "xxx";

 

mekabe remain

thank you all.

I already have 

data = JSON.stringify(data);

in the code.

then I will have to go like data.wetaher.monday...

?

 

AVSukhov

Hello,

JSON.stringify - converts the JavaScript value in a JSON string

You don`t need call JSON.stringify.

 

mekabe remain

ok; then what should I use to access information in "data" ?

thx.

 

Marco Buettner

You have to call the keys!

For example you have the follow JSON

var data = {"key1":"value1", "key2":[item1, item2, item3], "key3":0};

Than you can use

console.log(data.key1); // returns > value1
console.log(data.key2); // returns > object Object/Array
console.log(data.key3); // returns > 0
// thats equal to
console.log(data[key1]);
console.log(data[key2]);
console.log(data[key3]);

You can find all to know on json.org

mekabe remain

thank you.

I will try that.

 

mekabe remain

Hi,

No matter what I do, I get either "undefined" or the code crash.

My data sample is like:

 

data = {
"1":{"state": {"on":true,"bri":254,"hue":4377,"sat":26,"xy":[0.4059,0.3746],"ct":284,"alert":"none","effect":"none","colormode":"xy","reachable":true}, "type": "Extended color light", "name": "SalonYemek", "modelid": "LCT001","uniqueid":"00:17:88:01:00:bf:7f:5a-0b", "swversion": "66010820", "pointsymbol": { "1":"none", "2":"none", "3":"none", "4":"none", "5":"none", "6":"none", "7":"none", "8":"none" }},
"2":{"state": {"on":true,"bri":254,"hue":4377,"sat":26,"xy":[0.4059,0.3746],"ct":284,"alert":"none","effect":"none","colormode":"hs","reachable":true}, "type": "Extended color light", "name": "SalonTvSag", "modelid": "LCT001","uniqueid":"00:17:88:01:00:bf:1c:c9-0b", "swversion": "66010820", "pointsymbol": { "1":"none", "2":"none", "3":"none", "4":"none", "5":"none", "6":"none", "7":"none", "8":"none" }},
}

 

So, I want to get names of each entry.

I don't do any JSON.parse or JSON.stringify

And I use;

data.1.name

data.2.name

 

Why do I get undefined ?

Thanks.

Marco Buettner

Use JSON.parse before your try to access the data

mekabe remain

I did that but it didn't change the result.

Is this correct:

 

var test;
var name;

test=JSON.parse(data);
name=test.1.name;

 

mekabe remain

when I do JSON.stringify(data) , I can see the text as I copied in my previous post.

 

Mark as answer
AVSukhov

Hello,

Try to use:

name=test[1].name;

mekabe remain

ok; I will try that tonight. 

First JSON.parse , then test[1].name format. Correct ?

 

 

mekabe remain

it works.

thanks.

 

colin Rao
Suggest to avoid use a pure number as a key in JSON object. Mostly, a number is meaningless as a key.
mekabe remain

@colin Rao, thanks for the information but this is not my JSON object. It is how Philips designed Hue API.

:)