Extracting the first image from a JSON string/array

I'm trying to get a fake movie website going for a University project. But because I'm a designer, I'm terrible at php (and my terminology is probably way off). Let me know if something doesn't make sense or is badly explained.

I'm using http://themoviedb.org's API to bring in movie data, and am struggling on one of the pages.

I'm pulling a JSON string in from their API, and trying to get the first 'backdrop' image to display (there are high ranging numbers of backdrops per different movie, from none up to about twenty). There are different sizes of 'backdrop' as well, ranging from the 'original' size, down to a 'thumb'. I'm trying to pull in just the first 'backdrop' which is called the size 'poster'.

So here's what I've got. The problem is - to me - it looks perfectly structured, but just returns the fallback 'no-backdrop.gif'.

<?php
    //TMDb id for a movie
    $tmdb_id = $_GET["id"];

    //Search Movie with default return format
    $movies_result = $tmdb->getMovie($tmdb_id);

    // Decode JSON into PHP array
    $movies = json_decode($movies_result);
?>
<?php
    // Set default poster image to use if movie doesn't have one
    $backdrop_url = 'no-backdrop.gif';

    if ($movies[0]->backdrops->image->size == 'poster') {
      $backdrop_url = $movies[0]->backdrops->image->url;
    }

    echo '<img src="' . $backdrop_url . '" />';
?>

And here's is the json string. Which is massive unfortunately, so I've had to cut out what seems to be irrelevant to me.

The full string can be found at the bottom of the page on the link below.

Array ( [0] => stdClass Object ( ......... [backdrops] => Array ( [0] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/9b1/4d0095bd7b9aa1514a0069b1/black-swan-original.jpg [id] => 4d0095bd7b9aa1514a0069b1 ) ) [1] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/9b1/4d0095bd7b9aa1514a0069b1/black-swan-poster.jpg [id] => 4d0095bd7b9aa1514a0069b1 ) ) [2] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/9b1/4d0095bd7b9aa1514a0069b1/black-swan-thumb.jpg [id] => 4d0095bd7b9aa1514a0069b1 ) ) [3] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/9b1/4d0095bd7b9aa1514a0069b1/black-swan-w1280.jpg [id] => 4d0095bd7b9aa1514a0069b1 ) ) [4] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/9bb/4d00977f7b9aa1514a0069bb/black-swan-original.jpg [id] => 4d00977f7b9aa1514a0069bb ) ) [5] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/9bb/4d00977f7b9aa1514a0069bb/black-swan-poster.jpg [id] => 4d00977f7b9aa1514a0069bb ) ) [6] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/9bb/4d00977f7b9aa1514a0069bb/black-swan-thumb.jpg [id] => 4d00977f7b9aa1514a0069bb ) ) [7] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/9bb/4d00977f7b9aa1514a0069bb/black-swan-w1280.jpg [id] => 4d00977f7b9aa1514a0069bb ) ) [8] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/172/4d06bcb07b9aa11bc4003172/black-swan-original.jpg [id] => 4d06bcb07b9aa11bc4003172 ) ) [9] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/172/4d06bcb07b9aa11bc4003172/black-swan-poster.jpg [id] => 4d06bcb07b9aa11bc4003172 ) ) [10] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/172/4d06bcb07b9aa11bc4003172/black-swan-thumb.jpg [id] => 4d06bcb07b9aa11bc4003172 ) ) [11] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/172/4d06bcb07b9aa11bc4003172/black-swan-w1280.jpg [id] => 4d06bcb07b9aa11bc4003172 ) ) [12] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/c50/4d4708625e73d65704003c50/black-swan-original.jpg [id] => 4d4708625e73d65704003c50 ) ) [13] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/c50/4d4708625e73d65704003c50/black-swan-poster.jpg [id] => 4d4708625e73d65704003c50 ) ) [14] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/c50/4d4708625e73d65704003c50/black-swan-thumb.jpg [id] => 4d4708625e73d65704003c50 ) ) [15] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/c50/4d4708625e73d65704003c50/black-swan-w1280.jpg [id] => 4d4708625e73d65704003c50 ) ) [16] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/452/4d0a52997b9aa162af000452/black-swan-original.jpg [id] => 4d0a52997b9aa162af000452 ) ) [17] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/452/4d0a52997b9aa162af000452/black-swan-poster.jpg [id] => 4d0a52997b9aa162af000452 ) ) [18] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/452/4d0a52997b9aa162af000452/black-swan-thumb.jpg [id] => 4d0a52997b9aa162af000452 ) ) [19] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/452/4d0a52997b9aa162af000452/black-swan-w1280.jpg [id] => 4d0a52997b9aa162af000452 ) ) [20] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/443/4d0a514c7b9aa162af000443/black-swan-original.jpg [id] => 4d0a514c7b9aa162af000443 ) ) [21] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/443/4d0a514c7b9aa162af000443/black-swan-poster.jpg [id] => 4d0a514c7b9aa162af000443 ) ) [22] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/443/4d0a514c7b9aa162af000443/black-swan-thumb.jpg [id] => 4d0a514c7b9aa162af000443 ) ) [23] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/443/4d0a514c7b9aa162af000443/black-swan-w1280.jpg [id] => 4d0a514c7b9aa162af000443 ) ) [24] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/1af/4cd5d8597b9aa11b270001af/black-swan-original.jpg [id] => 4cd5d8597b9aa11b270001af ) ) [25] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/1af/4cd5d8597b9aa11b270001af/black-swan-poster.jpg [id] => 4cd5d8597b9aa11b270001af ) ) [26] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/1af/4cd5d8597b9aa11b270001af/black-swan-thumb.jpg [id] => 4cd5d8597b9aa11b270001af ) ) [27] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/1af/4cd5d8597b9aa11b270001af/black-swan-w1280.jpg [id] => 4cd5d8597b9aa11b270001af ) ) [28] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/453/4d0a527d7b9aa162bf000453/black-swan-original.jpg [id] => 4d0a527d7b9aa162bf000453 ) ) [29] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/453/4d0a527d7b9aa162bf000453/black-swan-poster.jpg [id] => 4d0a527d7b9aa162bf000453 ) ) [30] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/453/4d0a527d7b9aa162bf000453/black-swan-thumb.jpg [id] => 4d0a527d7b9aa162bf000453 ) ) [31] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/453/4d0a527d7b9aa162bf000453/black-swan-w1280.jpg [id] => 4d0a527d7b9aa162bf000453 ) ) [32] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/ed2/4d616c627b9aa154bf004ed2/black-swan-original.jpg [id] => 4d616c627b9aa154bf004ed2 ) ) [33] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/ed2/4d616c627b9aa154bf004ed2/black-swan-poster.jpg [id] => 4d616c627b9aa154bf004ed2 ) ) [34] =>开发者_运维百科; stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/ed2/4d616c627b9aa154bf004ed2/black-swan-thumb.jpg [id] => 4d616c627b9aa154bf004ed2 ) ) [35] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/ed2/4d616c627b9aa154bf004ed2/black-swan-w1280.jpg [id] => 4d616c627b9aa154bf004ed2 ) ) [36] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => original [height] => 1080 [width] => 1920 [url] => http://cf1.imgobject.com/backdrops/486/4d0a526e7b9aa162b7000486/black-swan-original.jpg [id] => 4d0a526e7b9aa162b7000486 ) ) [37] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => poster [height] => 439 [width] => 780 [url] => http://cf1.imgobject.com/backdrops/486/4d0a526e7b9aa162b7000486/black-swan-poster.jpg [id] => 4d0a526e7b9aa162b7000486 ) ) [38] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => thumb [height] => 169 [width] => 300 [url] => http://cf1.imgobject.com/backdrops/486/4d0a526e7b9aa162b7000486/black-swan-thumb.jpg [id] => 4d0a526e7b9aa162b7000486 ) ) [39] => stdClass Object ( [image] => stdClass Object ( [type] => backdrop [size] => w1280 [height] => 720 [width] => 1280 [url] => http://cf1.imgobject.com/backdrops/486/4d0a526e7b9aa162b7000486/black-swan-w1280.jpg [id] => 4d0a526e7b9aa162b7000486 ) ) ) ......... ) ) 

or to see it failing in action, you could go here - http://rowancavanagh.com/getfilm/tmdb_movie.php?id=44214

(complete with the json string printed at the bottom)

---

The backdrops property is an array, you have to access it as an array:

$backdrop_url = $movies[0]->backdrops[0]->image->url;

Try turning on error_reporting and/or display_errors or log_errors, this is an error that is easily caught with these on: "Trying to get property of non-object".

Also, use isset in your if to prevent an E_NOTICE from popping if there is no image:

if (isset($movies[0]->backdrops[0]->image->size) &&
    $movies[0]->backdrops[0]->image->size == 'poster') 
{
    // stuff
}

If you have more than one element in backdrops, and want to fetch only the one with the poster type, use a foreach loop:

foreach ($movies[0]->backdrops as $backdrop) {
    if (isset($backdrop->image->size) && $backdrop->image->size == 'poster') {
        $backdrop_url = $backdrop->image->url;
        break;
    }
}