Length of array in JSON object is returning undefined

Question

I am retrieving JSON data from a PHP file like so:

$.getJSON('fresh_posts.php',function(data){
    global_save_json = data.freshcomments;
    var countPosts = data.freshposts;
    var howManyPosts = countPosts.length;

I need to get the length of the first main array in the object, but there is an issue.

howManyPosts is returning undefined.

The JSON object from freshposts.php looks like this:

{ 
    "freshposts":{

         // two example posts with ID 5 and 2

        "5": {
            "id":"5",
            "image":"link.jpg",
            "submitter":"4322309",
            "views":"3"
        },
        "2": {
            "id":"2",
            "image":"link.jpg",
            "submitter":"4322309",
            "views":"5"
        }
    },

    // now each comment tied to the posts

    "freshcomments":{
        "2": [{
            "id":"1",
            "submitter":"submitter",
            "time":"2435657",
            "comment":"comment",
            "score":"10",
            "postid":"2"
        },
        {
            "id":"2",
            "submitter":"submitter",
            "time":"2435657",
            "comment":"comment",
            "score":"10",
            "postid":"2"
        }
    ],
        "5": [{
            "id":"3",
            "submitter":"submitter",
            "time":"2435657",
            "comment":"comment",
            "score":"10",
            "postid":"5"
        }]
    }
}

What is causing this?

Ah, it's an object? How would I get how many elements are in the object then? — frosty
– frosty, Commented Jun 9, 2015 at 21:02
Better yet, make it an array, rather than hacking around the fact that you're returning a semantically incorrect data type. — Chris Hayes
– Chris Hayes, Commented Jun 9, 2015 at 21:03

Vadim · Accepted Answer · 2015-06-09 21:05:09Z

2

You should do something like:

$.getJSON('fresh_posts.php',function(data){
    global_save_json = data.freshcomments;
    var countPosts = Object.keys(data.freshposts).length;
});

answered Jun 9, 2015 at 21:05

Vadim

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Comments

frontend_dev · Accepted Answer · 2015-06-09 21:02:44Z

2

"freshposts" is not an array it's an object:

"freshposts": { ... }

It should look like this:

"freshposts": [ ... ]

answered Jun 9, 2015 at 21:02

frontend_dev

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