Get undefined property error while extracting data from JSON string?

Question

I have following JSON string

{
"data": [
{
  "id": "533513150124231",
  "created_time": "2015-02-27T05:23:02+0000",
  "photos": {
    "data": [
      {
        "images": [
          {
            "height": 667,
            "source": "https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/10418414_555711037904442_8567793956228056677_n.jpg?oh=a8815f978e43abb98ab229cf83c85264&oe=559AB81A&__gda__=1440316102_f98baa62cfba9d6f94cd327f682ffd25",
            "width": 460
          },
          {
            "height": 464,
            "source": "https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/p320x320/10418414_555711037904442_8567793956228056677_n.jpg?oh=d35e77306662faecf87e744605d307bd&oe=559A52BE&__gda__=1436229856_60f872b53adcbf8aa302903fb019b327",
            "width": 320
          },
          {
            "height": 540,
            "source": "https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/p180x540/10418414_555711037904442_8567793956228056677_n.jpg?oh=b759bdb9362c6bfee5aa2709928d8f69&oe=559CEC03&__gda__=1436252765_64a5b0e1c663efead53300007c437990",
            "width": 372
          },
          {
            "height": 188,
            "source": "https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/p130x130/10418414_555711037904442_8567793956228056677_n.jpg?oh=cde013e3d7e9b2433e57b66e33167d92&oe=55A6CED1&__gda__=1436392591_2d5580f28f551316f45bc3930c459386",
            "width": 130
          },
          {
            "height": 225,
            "source": "https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/p75x225/10418414_555711037904442_8567793956228056677_n.jpg?oh=a5caf9c528ba7a8f8380db27d42f82c0&oe=55E49852&__gda__=1436028283_98c7a7d639ed37620f3a9b0fbb78472e",
            "width": 155
          }
        ],
        "created_time": "2015-04-17T06:00:00+0000",
        "id": "555711037904442"
      }
    ],
    "paging": {
      "cursors": {
        "before": "NTU1NzExMDM3OTA0NDQy",
        "after": "NTU1NzExMDM3OTA0NDQy"
      },
      "next": "https://graph.facebook.com/v2.3/533513150124231/photos?pretty=0&fields=images&limit=1&after=NTU1NzExMDM3OTA0NDQy"
    }
  }
},
{
  "id": "533911933417686",
  "created_time": "2015-02-28T07:18:09+0000",
  "photos": {
    "data": [
      {
        "images": [
          {
            "height": 960,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/11156332_555538204588392_7524203027467514208_n.jpg?oh=472d4dc677b7c6a1358bf59392071039&oe=55A97829&__gda__=1436014225_b6c761b77d7659f3499c98fa870efdd7",
            "width": 960
          },
          {
            "height": 720,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p720x720/11156332_555538204588392_7524203027467514208_n.jpg?oh=e9a1b55146bf65d1779fcfabe063012e&oe=55D62F58&__gda__=1437234622_80c2bf1dbec64f6851b15b9d33084b21",
            "width": 720
          },
          {
            "height": 600,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p600x600/11156332_555538204588392_7524203027467514208_n.jpg?oh=0126ec5adea74e13252a3bafaba14a02&oe=55A67B37&__gda__=1440779729_3645ddf066d0158821f83f8ea077b05f",
            "width": 600
          },
          {
            "height": 480,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p480x480/11156332_555538204588392_7524203027467514208_n.jpg?oh=2d60610a0e588be12333f1c89d9a2317&oe=559A8CD7&__gda__=1435982897_782ac7a2cc1c6cafac63aaef4a29ae4f",
            "width": 480
          },
          {
            "height": 320,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p320x320/11156332_555538204588392_7524203027467514208_n.jpg?oh=4148aaca5b81862a626b5399db291ba9&oe=559F338D&__gda__=1440297579_389092cfce5f8aafef4573968409e819",
            "width": 320
          },
          {
            "height": 540,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p180x540/11156332_555538204588392_7524203027467514208_n.jpg?oh=d4f772948708181ba7004e7f324988c9&oe=55E13930&__gda__=1436695254_4f2c082572f0241510ab59504fadfc3e",
            "width": 540
          },
          {
            "height": 130,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p130x130/11156332_555538204588392_7524203027467514208_n.jpg?oh=e095b6eaa807792afbfeaa2ed85f276b&oe=55A501E2&__gda__=1437193220_18d71223bd95cf5cba2542a11c24d18e",
            "width": 130
          },
          {
            "height": 225,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p75x225/11156332_555538204588392_7524203027467514208_n.jpg?oh=8e3f487af88e40470b93073853e3e8c7&oe=55A95661&__gda__=1436678326_211dc38936f310d46801ffea0582a646",
            "width": 225
          }
        ],
        "created_time": "2015-04-16T16:40:57+0000",
        "id": "555538204588392"
      }
    ],
    "paging": {
      "cursors": {
        "before": "NTU1NTM4MjA0NTg4Mzky",
        "after": "NTU1NTM4MjA0NTg4Mzky"
      },
      "next": "https://graph.facebook.com/v2.3/533911933417686/photos?pretty=0&fields=images&limit=1&after=NTU1NTM4MjA0NTg4Mzky"
    }
  }
},
{
  "id": "533471226795090",
  "created_time": "2015-02-27T03:20:20+0000",
  "photos": {
    "data": [
      {
        "images": [
          {
            "height": 252,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/10384022_533471210128425_1090655257311798538_n.png?oh=42293c184f93099fed226845661e68ba&oe=55A8A0BC&__gda__=1440376580_7355eccec9a71b9c1b1c3fb08b7c438d",
            "width": 785
          },
          {
            "height": 130,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p130x130/10384022_533471210128425_1090655257311798538_n.png?oh=61e2595ba9367c63ce4c31272d2f5965&oe=55E1AE77&__gda__=1440510353_4d66bcf977355eb4514d6ef5b665f496",
            "width": 404
          },
          {
            "height": 225,
            "source": "https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p75x225/10384022_533471210128425_1090655257311798538_n.png?oh=331aad239450d4f3d7f6984bae23a2e6&oe=55E237F4&__gda__=1440632867_d90a8c45baa7d4d4cdaa87346095b863",
            "width": 700
          }
        ],
        "created_time": "2015-02-27T03:20:21+0000",
        "id": "533471210128425"
      }
    ],
    "paging": {
      "cursors": {
        "before": "NTMzNDcxMjEwMTI4NDI1",
        "after": "NTMzNDcxMjEwMTI4NDI1"
      }
    }
  }
},
{
  "id": "533470536795159",
  "created_time": "2015-02-27T03:16:54+0000",
  "photos": {
    "data": [
      {
        "images": [
          {
            "height": 320,
            "source": "https://scontent.xx.fbcdn.net/hphotos-xfa1/v/t1.0-9/10431515_533470543461825_4940061426497683241_n.jpg?oh=b7c513e31c9dc4da9e64df4094280a70&oe=559D578E",
            "width": 240
          },
          {
            "height": 173,
            "source": "https://scontent.xx.fbcdn.net/hphotos-xfa1/v/t1.0-9/p130x130/10431515_533470543461825_4940061426497683241_n.jpg?oh=d4d3e16d0cc7b43e9ae44df494f08e29&oe=55D70A45",
            "width": 130
          },
          {
            "height": 225,
            "source": "https://scontent.xx.fbcdn.net/hphotos-xfa1/v/t1.0-9/p75x225/10431515_533470543461825_4940061426497683241_n.jpg?oh=5d8e3097a633df2c9ca86de0be65622f&oe=5599C4C6",
            "width": 168
          }
        ],
        "created_time": "2015-02-27T03:16:55+0000",
        "id": "533470543461825"
      }
    ],
    "paging": {
      "cursors": {
        "before": "NTMzNDcwNTQzNDYxODI1",
        "after": "NTMzNDcwNTQzNDYxODI1"
      }
    }
  }
}
],
"paging": {
"cursors": {
  "after": "NTMzNDcwNTM2Nzk1MTU5",
  "before": "NTMzNTEzMTUwMTI0MjMx"
}
}
}

I got this string from Facebook Graph API explorer. After that I tried to extract image source from this JSON data. Here is the code I wrote.

$output = 'All the JSON data above is written here';
$output = json_decode($output);

for($i=0;$i<2;$i++)
{
$image = $output->photos->data->images[$i][0]->source;
echo $image.'</br>';
}

With this code I get following error

 Undefined property: stdClass::$photos on line 1796
 Trying to get property of non-object on line 1796

I want to extract source for first image in each category like this

https://www.facebook.com/l.php?u=https%3A%2F%2Fscontent.xx.fbcdn.net%2Fhphotos-xfa1%2Fv%2Ft1.0-9%2F10431515_533470543461825_4940061426497683241_n.jpg%3Foh%3Db7c513e31c9dc4da9e64df4094280a70%26oe%3D559D578E&h=8AQE_FhcA

Kevin · Accepted Answer · 2015-04-17 07:41:50Z

1

I'd suggest an alternative with foreach. You can use it also to traverse the decoded JSON:

foreach($output->data as $data) {
    $photos = $data->photos->data[0]->images;
    foreach($photos as $img) {
        echo "{$img->source} <br/>";
    }
}

By the way, that traverses all of the source batches, you'd want the first one, you can use reset to get the first one on the current batch, then point to the property:

foreach($output->data as $data) {
    $photos = $data->photos->data[0]->images;
    $first = reset($photos)->source;
    echo "{$first} <br/>";
}

edited Apr 17, 2015 at 7:41

answered Apr 17, 2015 at 7:32

Kevin

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2 Comments

Sandip Patel Over a year ago

I am using $data->photos->data[0]->images[0]->source to get first image instead. Will it give me wrong results?

Kevin Over a year ago

@SandipPatel no, its also the same, i just use reset for this example, pointing to it directly into index 0 will also work just fine

Klitos G. · Accepted Answer · 2015-04-17 07:32:03Z

0

Try to follow your json tree. Change $image = $output->photos->data->images[$i][0]->source; To $image = $output->data->photos->data->images[$i][0]->source;

answered Apr 17, 2015 at 7:32

Klitos G.

8565 silver badges15 bronze badges

1 Comment

Sandip Patel Over a year ago

I still get Trying to get property of non-object this error.

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