JavaScript Parsing Complex JSON

Question

I have the follwing JSON:

{  
   "_id":"9876567833",
   "result":{  
      "Mercedes":[  
         {  
            "category_name":"Car"
         },
         {  
            "category_name":"Fast"
         }
      ],
      "BMW":[  
         {  
            "category_name":"Car"
         }
      ]
   }

I don't know before "Mercedes" or "BMW" (it could change, this is just for the example). I need to get "Car", "Fast", "Car".

The JSON is in categories So I tried:

    var categoArray = [];
    for(var i =0; i < categories.length; i++){
        for (var idx in categories[i].result) {
               if (categories[i].result[idx].length > 0){
                   categoArray.push(categories[i].result[idx].category_name);
          }
         }
       }

But it doesn't work.

[EDIT] It is not the same :Access / process (nested) objects, arrays or JSON

My question is much more complex

Thanks for your help!

You are testing `categories[i].result[idx].length`, which, I assume, you are doing because `categories[i].result[idx]` is an array. Then why are you accessing `categories[i].result[idx].category_name`? Arrays don't have such a property. — Felix Kling, Oct 31 '14 at 15:01
The thing is I would like the stuff in "category_name": like "Car", "Fast", "Car" — Jose, Oct 31 '14 at 15:03
@Jose: Is this what you are after: http://jsfiddle.net/abhitalks/3Lx6n2d4/ ? Or this: http://jsfiddle.net/abhitalks/5epj4ywu/ — Abhitalks, Oct 31 '14 at 15:07
I understand that. I'm just surprised that you seem to know that `categories[i].result[idx]` is an array (otherwise you wouldn't check `length`) and still try to access `category_name` on the *array* instead on one of its *elements*. — Felix Kling, Oct 31 '14 at 15:18

score 3 · Answer 1 · edited Oct 31 '14 at 14:59

3

You're close, but you need 1 more loop:

var categoArray = [];
for (var i = 0; i < categories.length; i++) {
    for (var key in categories[i].result) {
        for (var j = 0; j < categories[i].result[key].length; j++) {
            categoArray.push(categories[i].result[key][j].category_name);
        }
    }
}

edited Oct 31 '14 at 14:59

Felix Kling

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answered Oct 31 '14 at 14:54

tymeJV

103,943
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Still have an error TypeError: Cannot read property 'category_name' of undefined – Jose Oct 31 '14 at 14:58

score 0 · Answer 2 · answered Oct 31 '14 at 14:55

0

categories[i].result[idx] returns an array, not an object. Therefore, categories[i].result[idx].category_name will be undefined.

answered Oct 31 '14 at 14:55

Rodney G

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1
16
15

yes :( TypeError: Cannot read property 'category_name' of undefined – Jose Oct 31 '14 at 15:01

JavaScript Parsing Complex JSON

2 Answers2