Getting token works, but making payment not - paypal

Question

I'm making a class to make a payment with paypal.
Getting a token via the function getToken() works and it spits out a good response (according to the documentation).
However, when I'm using that token to build up a payment with the same sendAPICall() used for the token; it only returns a empty string (according to var_dump() ).
If I copy the exact curl command from the api-information and paste the beare-token; it works. So something is wrong with my API call....
Clearly I'm missing something. Could anyone point me to the error?
The function which gets the Bearer-token:
public function getToken(){
$headers = array(
"Accept-Language" => 'en_US',
"Accept" => "application/json"
);
$t = json_decode($this->sendAPICall('grant_type=client_credentials', '/oauth2/token', $headers, true));
if($t->error){
$this->error = $t->error_description;
$this->token = NULL;
return false;
}else{
$this->token = $t;
return true;
}
}
The function which should make the payment after checking there is a token available.
public function makePayment(){
$this->getToken();
if($this->error){
return false;
}else{
$d = '{"intent":"sale",
"redirect_urls":{
"return_url":"'.$this->config['returnURL'].'",
"cancel_url":"'.$this->config['cancelURL'].'"
},
"payer":{
"payment_method":"paypal"
},
"transactions":[
{
"amount":{
"total":"'.$this->amount.'",
"currency":"'.$this->config['currency'].'"
},
"description":"'.$this->description.'"
}
]
}';
$headers = array( "Authorization" => $this->token->token_type . ' ' . $this->token->access_token,
"Content-type" => "application/json"
);
return $this->sendAPICall(urlencode($d), '/payments/payment', $headers, false);
}
}
And off course the connection with the paypal API, where I'm using the $auth boolean to make the difference between sending the userpwd or using the token:
private function sendAPICall($data, $url, $headers, $auth=true){
$ch = curl_init();
$options = array( CURLOPT_URL => $this->config['endpoint'].$url,
CURLOPT_POST => true,
CURLOPT_POSTFIELDS => $data,
CURLOPT_RETURNTRANSFER => true
);
if($auth){
$options[CURLOPT_USERPWD] = $this->config['client_id'].':'.$this->config['client_secret'];
};
curl_setopt_array($ch, $options);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
return curl_exec($ch);
}

Answer 1

It does not look like this code snippet is passing HTTP headers correctly. CURLOPT_HTTPHEADER takes a unideimensional array with values of the form "headername: value". You need
$headers = array(
"Authorization: " . $this->token->token_type . ' ' . $this->token->access_token,
"Content-type: application/json"
);
Also consider
Checking for curl_errno($ch) / curl_error($ch) and the HTTP response code (curl_getinfo($ch, CURLINFO_HTTP_CODE)) to see if the call was successful.
Creating the request data as an associative array and using json_encode($data) when calling sendAPICall(). This is far easier than manipulating JSON strings manually.