Upload multiple images with PHP Curl

Question

I'm trying to upload more than one image with PHP Curl. The API I'm using gives me the following example:

curl -v -s -u username:password \
 -H "Content-Type: multipart/form-data" \
 -H "Accept: application/vnd.com.example.api+json" \
 -F "[email protected];type=image/jpeg" \
 -F "[email protected];type=image/jpeg" \
 -XPUT 'https://example.com/api/sellers/12/ads/217221/images'

So in my php script I tried this:

$files = array();

foreach($photos as $photo) {
    $cfile = new CURLFile('../' . $photo, 'image/jpeg', 'test_name');
    $files[] = $cfile;
}

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://services.example.com/seller-api/sellers/' . $seller . '/ads/' . $voertuig_id . '/images');
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
curl_setopt($ch, CURLOPT_POSTFIELDS, $files);
curl_setopt($ch, CURLOPT_PROXY,'api.test.sandbox.example.com:8080');
curl_setopt($ch, CURLOPT_USERPWD, 'USER:PASS');
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 1);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Host: services.example.com',
    'Content-type: multipart/form-data; boundary=vjrLefDejJaWiU0JzZfsadfasd1rMcE2HQ-n7XsSx',
    'Accept: application/vnd.com.example.api+json'
));

$output = curl_exec($ch);

curl_close($ch);

First I got this response from the API:

 {
   "errors":{
      "error":{
         "@key":"unsupported-form-element"
      }
   }
}

but now there is no response at all. How do I use curl to upload multiple files?

if $files is an empty JSON for example, it gives no error at all and returns the images (empty ofcourse).

This is the documentation of the API I'm using: https://services.mobile.de/manual/new-seller-api.html#_upload_images

EDIT: I tried to build the request body and send it, but it doesn't do anything:

$requestBody = '';
$requestBody .= '--vjrLeiXjJaWiU0JzZkUPO1rMcE2HQ-n7XsSx\r\n';
$requestBody .= 'Content-Disposition: form-data; name="image"; filename="ferrari.JPG"\r\n';
$requestBody .= 'Content-Type: image/jpeg\r\n';
$requestBody .= 'Content-Transfer-Encoding: binary\r\n';

curl_setopt($ch, CURLOPT_POSTFIELDS, $requestBody);

Answer 1

try use assoc array, how it use into documentation CURLFile

$photos = [
    'img1' => 'img1.jpg',
    'img2' => 'img2.jpg'
]

$files = [];

foreach($photos as $key => $photo) {
    $cfile = new CURLFile('../' . $photo, 'image/jpeg', $key);
    $files[$key] = $cfile;
}

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://services.example.com/seller-api/sellers/' . $seller . '/ads/' . $voertuig_id . '/images');
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
curl_setopt($ch, CURLOPT_POSTFIELDS, $files);
curl_setopt($ch, CURLOPT_PROXY,'api.test.sandbox.example.com:8080');
curl_setopt($ch, CURLOPT_USERPWD, 'USER:PASS');
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 1);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Host: services.example.com',
    'Content-type: multipart/form-data; boundary=vjrLefDejJaWiU0JzZfsadfasd1rMcE2HQ-n7XsSx',
    'Accept: application/vnd.com.example.api+json'
));

$output = curl_exec($ch);

curl_close($ch);