Can't deal with foreach levels with JSON decoding - php

Question

I've been dealing with this problem around 5 hours, so I think that's time to ask here.
I'm retrieving data using Facebook Graph API and using JSON decoding to put it all together on a PHP.
Here's FB Graph:
{
"feed": {
"data": [
{
"message": "A file.",
"id": "831407506978898_831408573645458",
"attachments": {
"data": [
{
"target": {
"id": "1041214692589250",
"url": "https://www.facebook.com/download/A-PDF-FILE.pdf"
},
"title": "Clase 01 - Vías de administración.pdf",
"type": "file_upload",
"url": "https://www.facebook.com/download/A-PDF-FILE.pdf"
}
]
}
},
{
"picture": "https://fbcdn-photos-c-a.akamaihd.net/A-PHOTO.jpg",
"message": "A photo.",
"id": "831407506978898_831408496978799",
"attachments": {
"data": [
{
"description": "A photo.",
"media": {
"image": {
"height": 540,
"src": "https://fbcdn-photos-c-a.akamaihd.net/A-PHOTO.jpg",
"width": 720
}
},
"target": {
"id": "10207838160017396",
"url": "https://fbcdn-photos-c-a.akamaihd.net/A-PHOTO.jpg"
},
"type": "photo",
"url": "https://fbcdn-photos-c-a.akamaihd.net/A-PHOTO.jpg"
}
]
}
},
{
"picture": "https://fbcdn-photos-c-a.akamaihd.net/A-PHOTO.jpg",
"id": "831407506978898_831408450312137",
"attachments": {
"data": [
{
"media": {
"image": {
"height": 540,
"src": "https://fbcdn-photos-c-a.akamaihd.net/A-PHOTO.jpg",
"width": 720
}
},
"target": {
"id": "10207838168217601",
"url": "https://fbcdn-photos-c-a.akamaihd.net/A-PHOTO.jpg"
},
"type": "photo",
"url": "https://fbcdn-photos-c-a.akamaihd.net/A-PHOTO.jpg"
}
]
}
},
{
"message": "TEST",
"id": "831407506978898_831407576978891"
},
{
"id": "831407506978898_831407516978897"
}
],
"paging": {
"previous": "https://graph.facebook.com/...alotofjunk"
}
},
"id": "0000000000000"
}
And my PHP is the following one:
<?php
header('Content-Type: text/html; charset=utf-8');
$limit = 60; // The number of posts fetched
$access_token='TOKEN NUMBER';
$group_id = 'GROUPNUMBER';
$url1 = 'https://graph.facebook.com/'.$group_id.'?access_token='.$access_token;
$des = json_decode(file_get_contents($url1)) ;
$url2 = "https://graph.facebook.com/{$group_id}/feed?access_token={$access_token}";
$data = json_decode(file_get_contents($url2));
?>
<?
$counter = 0;
foreach($data->data as $d) {
if($counter==$limit)
break;
?>
<? $themessage = (isset($d->message) ? $d->message : false); ?>
<? print $themessage ?>
<? $thepicture = (isset($d->picture) ? $d->picture : false); ?>
<? print "<img src=\"$thepicture\">" ?>
<!--THE PROBLEM IS FROM HERE.... -->
<?
$counter = 0;
foreach($d->attachments->data as $d2) {
if($counter==$limit)
break;
?>
<? $attachments = (isset($d2->url) ? $d2->url : false); ?>
<? print $attachments ?>
<?
}
?>
<!-- ...TO HERE -->
<?
$counter++;
}
?>
I get a perfect output of $themessage and $thepicture, but I with $attachments I receive the following errors:
Notice: Undefined property: stdClass::$attachments in...
Notice: Trying to get property of non-object in...
Warning: Invalid argument supplied for foreach() in...
I've already read this: Trouble with Facebook multi-level json php foreach loop, but no luck.
How can I fix this?. Thanks a lot!

Answer 1

You need to be careful when you're chaining objects - especially in loops. One empty object will bring down the whole show. Try this:
$counter = 0;
if( isset( $d->attachments ) )
{
foreach( $d->attachments->data as $d2 )
{
....
}
}

Answer 2

Notice: Undefined property: stdClass::$attachments in...
Notice: Trying to get property of non-object in...
Warning: Invalid argument supplied for foreach() in...
You're getting this error becoz you're missing feed object in your first loop
HereDEMO
Replace
foreach($data->data as $d) {
if($counter==$limit)
break;
?>
With
foreach($data->feed->data as $d) {
if($counter==$limit)
break;
?>
Your JSON is in this format paste your JSON here JSON Format Viewer and check it
I tried your code i'm able to get url printed HereDEMO
$data="Your JSON Here"
foreach($data->feed->data as $d) {
$themessage = (isset($d->message) ? $d->message : false);
print("\n".$themessage);
$thepicture = (isset($d->picture) ? $d->picture : false);
print("\n<img src='$thepicture'>");
foreach($d->attachments->data as $d2) {
$attachments = (isset($d2->url) ? $d2->url : false);
print("\n".$attachments);
}
}
Side Note: you're initailising $counter = 0; twice once inside loop
and outside the loop its bad Even for $attachment, Its my opinion after looking your code for first time whatever you're reason be behind it