error in Android: GCM using PHP - php

Question

I used following code in PHP to send GCM message to Android:
<?php
$apiKey = "xxxxx"; //my api key
$registrationIDs = array("APA91bGGN7o7AwVNnv35lwP5Jw8OTJQL331XcxPfEIu4xt-ZKLe6R0aSSbAve99uKSDXhzE9L2PVLihpqFt0DEawhymUs9h5ICbTMweMAEJypg6ZLFqmf6SOGlyULQzudw9MM1DjbPaaKbo--wxWoHGkjyec2H_63e7mesYjaRf4_rgxBe655M0");
// Message to be sent
$message = "Message Text";
// Set POST variables
$url = 'https://android.googleapis.com/gcm/send';
$fields = array(
'registration_ids' => $registrationIDs,
'data' => array( "message" => $message ),
);
$headers = array(
'Authorization: key=' . $apiKey,
'Content-Type: application/json'
);
// Open connection
$ch = curl_init();
// Set the url, number of POST vars, POST data
curl_setopt( $ch, CURLOPT_URL, $url );
curl_setopt( $ch, CURLOPT_POST, true );
curl_setopt( $ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch, CURLOPT_POSTFIELDS, json_encode( $fields ) );
// Execute post
$result = curl_exec($ch);
// Close connection
curl_close($ch);
echo $result;
It's working fine. Here I added my device tokens manually(hardcoded).
But when i tried getting device tokens from the database, I am getting below mentioned error.
Code:
<?php
include 'config.php';
if($_REQUEST['msg']!='')
{
echo $message = $_REQUEST['msg'];
// Replace with real BROWSER API key from Google APIs
$apiKey ="xxxxxx"; //my api key
// Replace with real client registration IDs
$sql = mysql_query("SELECT `device_token` FROM `users`");
$result = mysql_fetch_array($sql);
$registrationIDs = $result;
// Message to be sent
$message = $_REQUEST['msg'];
// Set POST variables
$url = 'https://android.googleapis.com/gcm/send';
$fields = array(
'registration_ids' => $registrationIDs,
'data' => array( "message" => $message ),
);
$headers = array(
'Authorization: key=' . $apiKey,
'Content-Type: application/json'
);
// Open connection
$ch = curl_init();
// Set the url, number of POST vars, POST data
curl_setopt( $ch, CURLOPT_URL, $url );
curl_setopt( $ch, CURLOPT_POST, true );
curl_setopt( $ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch, CURLOPT_POSTFIELDS, json_encode( $fields ) );
// Execute post
$result = curl_exec($ch);
// Close connection
curl_close($ch);
echo $result;
}
I also tried using json_encode($registration_ids) with no use.
"registration_ids" field is not a JSON array

Answer 1

I finally got a solution. I used a for loop to get all the results into an array and converted array into JSON array using json_encode();

Answer 2

I was getting the same error because my array indexes are not properly sorted I fix it by using PHP's sort() function.
Before Sort
$registration_ids = Array
(
[1] => "xxx"
[6] => "xxx"
[8] => "xxx"
)
Sort
sort($registration_ids);
After Sort
$registration_ids = Array
(
[0] => "xxx"
[1] => "xxx"
[2] => "xxx"
)
Pass to PHP's cURL
$fields = array(
'registration_ids' => $ids,
'data' => array('message' => $data)
);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));