JSON object returns undefined value

Question

I am receiving a JSON object from a http call and I am trying to extract values from it. JSON object contains:

data:{"userid":"007", "role":"spy"}

I use the following code to assign role property to another variable followed by some console log checks:

    currentUserRole = data.role;    
    console.log("type of data: "+typeof(data));
    console.log("data: "+JSON.stringify(data));
    console.log("user role: "+currentUserRole);

The logs produce:

type of data: object
data: [{"userid":"007", "role":"spy"}]
user role: undefined

Also I tried another method of assignment:

currentUserRole = data['role'];

But currentUserRole remains undefined. How can I set a property of a JSON object to a variable?

possible duplicate of Access / process (nested) objects, arrays or JSON — Felix Kling
– Felix Kling, Commented May 7, 2014 at 2:44
JSON.stringify(data) clearly shows that data is an array with one element, an object. — Felix Kling
– Felix Kling, Commented May 7, 2014 at 2:44
FYI: JSON is a string. You can't set properties on it. This doesn't have anything to do with JSON. — Hamish
– Hamish, Commented May 7, 2014 at 2:45

Adam Batkin · Accepted Answer · 2014-05-07 02:45:10Z

15

According to the second line of your log (the call to JSON.stringify()), your data is actually an array of objects:

[{"userid":"007", "role":"spy"}]

If it was an object as you are expecting, it would look like this:

{"userid":"007", "role":"spy"}

(the difference is subtle, but notice the missing square brackets)

Try this:

currentUserRole = data[0].role;

Obviously in production-ready code, you probably need to do some extra sanity checking to ensure that data is in fact an array containing at least one element.

answered May 7, 2014 at 2:45

Adam Batkin

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Jamsheed Kamarudeen · Accepted Answer · 2014-05-07 02:46:25Z

0

It is a list. Try data[0].role

answered May 7, 2014 at 2:46

Jamsheed Kamarudeen

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2 Comments

Taryn East Over a year ago

Hiya, I know this seems obvious to you, but don't forget that total n00bs will probably stumble across your solution at some future time. Can you give a brief explanation for why this solution works (in this case something about it being an object embedded in an array and needing to index into it first)? For The Children ;)

Jamsheed Kamarudeen Over a year ago

ofcourse. but now that someone else gave a good answer, I would leave it at that. Will do it in my later replies

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