json and empty array

Question

I have the following json :

{
   "users":
    [{
       "user": 
        {
        "user_id"  :"a11uhk22hsd3jbskj",
        "username" :"tom",
        "location" : null
        }
    }]
}

I get this json in response to a request to an api. Looking at the doc for this api, location is supposed to be an array (containing geodata, latitude, longitude address etc).
Now the question is : there's an error in the json? I mean, location doesn't seems,to me, to be an array, or is possible to represent a null array in that way? and if yes what is the difference between :

"location" : null 
"location" : []

Matt Varblow · Accepted Answer · 2011-11-12 13:05:10Z

44

"location" : null // this is not really an array it's a null object
"location" : []   // this is an empty array

It looks like this API returns null when there is no location defined - instead of returning an empty array, not too unusual really - but they should tell you if they're going to do this.

answered Nov 12, 2011 at 13:05

Matt Varblow

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1 Comment

niz_sh Over a year ago

Hi, How to check to empty array??

Hot Licks · Accepted Answer · 2011-11-12 13:04:56Z

28

null is a legal value (and reserved word) in JSON, but some environments do not have a "NULL" object (as opposed to a NULL value) and hence cannot accurately represent the JSON null. So they will sometimes represent it as an empty array.

Whether null is a legal value in that particular element of that particular API is entirely up to the API designer.

answered Nov 12, 2011 at 13:04

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Comments

Adam Zalcman · Accepted Answer · 2011-11-12 13:36:30Z

3

The first version is a null object while the second is an Array object with zero elements.

Null may mean here for example that no location is available for that user, no location has been requested or that some restrictions apply. Hard to tell with no reference to the API.

edited Nov 12, 2011 at 13:36

answered Nov 12, 2011 at 13:05

Adam Zalcman

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