Getting first object from a JSON file

Question

How do I get access to the "thumburl" if I do not know the "pageid"?

{
  "continue": {
    "iistart": "2004-12-19T12:37:26Z",
    "continue": "||"
  },
  "query": {
    "pages": {
      "30260": {
        "pageid": 30260,
        "ns": 6,
        "title": "File:Japanese diet inside.jpg",
        "imagerepository": "local",
        "imageinfo": [
          {
            "thumburl": "https://upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Japanese_diet_inside.jpg/130px-Japanese_diet_inside.jpg",
            "thumbwidth": 130,
            "thumbheight": 95,
            "url": "https://upload.wikimedia.org/wikipedia/commons/e/e1/Japanese_diet_inside.jpg",
            "descriptionurl": "https://commons.wikimedia.org/wiki/File:Japanese_diet_inside.jpg",
            "descriptionshorturl": "https://commons.wikimedia.org/w/index.php?curid=30260"
          }
        ]
      }
    }
  }
}

With multiple objects in php I can do this imageinfo[0] but If I put $imageurl = $data->query->pages[0]->imageinfo[0]->thumburl; It is not working because it is an object not an array.

How can I do that?

I think you got your answer Adrian. A few ways... now the hard part is choosing which one! :) — IncredibleHat
– IncredibleHat, Commented Mar 5, 2018 at 21:36
Thank you very much for the answers! I am trying all of the options but unsuccessful yet, I do not why. Once I have it working I will mark with the answer I used. — Adrian Vazquez
– Adrian Vazquez, Commented Mar 5, 2018 at 23:31

Barmar · Accepted Answer · 2018-03-05 21:29:01Z

3

You can call get_object_vars to get an associative array of the object properties, then get the first of these.

$props = array_values(get_object_vars($data->query->pages));
$imageurl = $props[0]->imageinfo[0]->thumburl;

edited Mar 5, 2018 at 21:29

answered Mar 5, 2018 at 21:14

Barmar

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3 Comments

Barmar Over a year ago

I was thinking of get_class_vars, which just returns an array of the property names. I've simplified this.

IncredibleHat Over a year ago

Yeah, your two-line approach above is clean n workin!

Adrian Vazquez Over a year ago

I really like this answer but I do not why is not working :(

Syscall · Accepted Answer · 2018-03-05 21:24:16Z

3

You could use reset() to get the first element :

$data = json_decode($json) ;
$elem = reset($data->query->pages) ;
$imageurl = $elem->imageinfo[0]->thumburl ;

answered Mar 5, 2018 at 21:24

Syscall

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6 Comments

Barmar Over a year ago

Does reset() really work with an object rather than an array?

Barmar Over a year ago

Don't see anything about it in php.net/manual/en/function.reset.php

IncredibleHat Over a year ago

I cannot explain it, but it does work when I slap that into my test server with the json example. :) So... yeah. Works too!

Syscall Over a year ago

@Barmar Seems to work in 5.3 too (sandbox.onlinephpfunctions.com/code/…)

salathe Over a year ago

It is an undocumented "feature" of reset() and other functions in its family, and the behaviour has been mostly consistent for several decades.

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AbraCadaver · Accepted Answer · 2018-03-05 21:46:00Z

2

Another alternative is to decode as an array and re-index so it always starts at 0:

$result = array_values(json_decode($json, true)['query']['pages'])[0];

Then you can access $result['imageinfo']['thumburl'] or append it to the above.

answered Mar 5, 2018 at 21:46

AbraCadaver

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Comments

MatejG · Accepted Answer · 2018-03-05 21:19:38Z

1

You can loop through it, so you don't need array key like this:

$pages = (array) $data->query->pages;
foreach($pages as $page) {
  $imageinfo = $page->imageinfo[0]->thumburl;
}

But this will get you only last from list of pages. So in case you know there are more pages, you need to store these thumburl in array. Or in case you are sure you want only first, just exit after first loop.

edited Mar 5, 2018 at 21:19

answered Mar 5, 2018 at 21:10

MatejG

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