doing .length on json array returns undefined

Question

I have following json encoded array coming from ajax call

{"country":{"0":"United States of America","United States of America":{"states":{"0":"Alaska","Alaska":{"cities":["Adak","Akiachak","Akiak","Akutan","Alakanuk"]}}}}}

Following is my ajax code

$.ajax({
   method: "POST",
   url: "test.php",
   data: "action=2",
   cache: 'false',
   success: function(abcd){
     alert(abcd);
     var obj = new Array();
     var obj = $.parseJSON(abcd);
     alert(obj.country.length);
   }
});

When i try using obj.country[0] it returns "United States of America". But when i try to get the length of the array using obj.country.length it returns undefined.

I have browsed a couple of posts and only difference i could see was use of dataType: json and using header() to define content type to json on .php page. I have tried both methods but that didn't work out either. And on .php page i have declared following as array:

$data = array();
$data['country'] = array();
$data['country']['United States of America'] = array();
$data['country']['United States of America']['states'] = array();
$data['country']['United States of America']['states']['Alaska']['cities'] = array();

gpgekko · Accepted Answer · 2014-01-28 11:14:14Z

3

This is because obj.country isn't an array, but an object.

An object is enclosed in curly braces ({}) and an array in square ones ([]). See http://json.org/ for more information.

In your example content, "cities":["Adak","Akiachak","Akiak","Akutan","Alakanuk"] would be an array, which you can call with obj["country"]["United States of America"]["states"]["Alaska"]["cities"].

So, judging from your example this would work:

$us['name'] = "United";
$alaska['name'] = "Alaska";
$alaska['cities'] = array("city1", "city2");
$us['states'] = array($alaska)
$data = array($us);

I expect it would render like [{"name": "United", "states": [{"name":"Alaska", "cities": ["city1","city2"]}]}].

I'm sure it could be done better or more compact though, I don't have much experience with PHP in this regard.

edited Jan 28, 2014 at 11:14

answered Jan 28, 2014 at 10:48

gpgekko

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11 Comments

Saad Bashir Over a year ago

Ok so how do I convert it to any array?

Amberlamps Over a year ago

You might want to add, that obj.country[0] actually returns a value, because there is an attribute called 0 within said object.

gpgekko Over a year ago

@SaadBashir If you can't change the source of the content, you will have to loop through the object and add every entry into a new array.

Saad Bashir Over a year ago

I can change the source of the content. But like I said I am already defining it as an array like I explained in the question. At every stage I have defined it as an array. I don't know what am I doing wrong here.

Amberlamps Over a year ago

@SaadBashir: In you PHP code you are overwritting the array definition with every assignment. If you encode it as JSON it will be an object, because Javascript does not know hashed arrays.

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Miraage · Accepted Answer · 2014-01-28 10:51:22Z

0

What about this?

alert((Object.keys(obj.country) || []).length);

answered Jan 28, 2014 at 10:51

Miraage

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2 Comments

Amberlamps Over a year ago

What about that? Add more information to your answer. What are you trying to accomplish with that? How is that helping OP?

Saad Bashir Over a year ago

Well yes this returns 2.

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