CURL: Send images with boundary to REST API

Question

Im currently working with some kind of API. I have wrote simple functions which allows me to add new content, however Im stuck on uploading images.

Here's simple CURL command in documentation:

curl -v -s -u username:password \
  -H "Content-Type: multipart/form-data" \
  -H "Accept: application/api+json" \
  -F "[email protected];type=image/jpeg" \
  -F "[email protected];type=image/jpeg" \
  -XPUT ''

And a sample REQUEST:

PUT /images HTTP/1.1
Host: example
Content-Type: multipart/form-data; boundary=vjrLeiXjJaWiU0JzZkUPO1rMcE2HQ-n7XsSx

--vjrLeiXjJaWiU0JzZkUPO1rMcE2HQ-n7XsSx
Content-Disposition: form-data; name="image"; filename="img1.jpg"
Content-Type: image/jpeg
Content-Transfer-Encoding: binary

Now, there is my function:

$headers_put = array( 
   "Content-Type: multipart/form-data; boundary=vjrLeiXjJaWiU0JzZkUPO1rMcE2HQ-n7XsSx",
   "Accept: application/+json",  
); 

function putImages($ch, $headers, $ad, $images){
    $url = '/images';

    $files = [];

    foreach($images as $key => $image) {
        $number = $key +1;
        $paths = parse_url($image, PHP_URL_PATH);
        $paths = $_SERVER['DOCUMENT_ROOT'] . $paths;

        $cfile = new CURLFile(''. $paths, 'image/jpeg', 'image'.$key);
        $files[$key] = $cfile;

    }

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'PUT');
    curl_setopt($ch, CURLOPT_POSTFIELDS, $files);

    $result = curl_exec($ch);
    var_dump($result);

    echo curl_getinfo($ch, CURLINFO_HTTP_CODE);
    echo "\n";

}

Finally, the response is:

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

What Im doing wrong? Any ideas? Thank you kindly for any help.

Answer 1

After several approaches using curl_file_create without getting it to work. I think the mobile.de-API is just implemented badly.

I ended up implementing a custom routine for CURLOPT_POSTFIELDS that is creating the complete multipart manually. I borrowed most of the code from the PHP manpage as "The CURLFile class".

1. Create an array of the filenames

2. Create multipart header (see code below)

   function curl_custom_postfields(array $files = array())    {
   
   // build file parameters
   foreach ($files as $k => $v) {
       switch (true) {
           case false === $v = realpath(filter_var($v)):
           case !is_file($v):
           case !is_readable($v):
               continue; // or return false, throw new InvalidArgumentException
       }
       $data = file_get_contents($v);
       $body[] = implode("\r\n", array(
           "Content-Disposition: form-data; name=\"image\"",
           "Content-Type: image/jpeg",
           "",
           $data,
       ));
   }
   
   // generate safe boundary
   do {
       $boundary = "---------------------" . md5(mt_rand() . microtime());
   } while (preg_grep("/{$boundary}/", $body));
   
   // add boundary for each parameters
   array_walk($body, function (&$part) use ($boundary) {
       $part = "--{$boundary}\r\n{$part}";
   });
   
   // add final boundary
   $body[] = "--{$boundary}--";
   $body[] = "";
   
   // set options
   return array(implode("\r\n", $body), $boundary);    
   }
   

3. Use that function ;)

   $postfields = $this->curl_custom_postfields($files);
   

4. Add boundary to http header

   curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: multipart/form-data; boundary=' . $postfields[1], 'Accept: application/vnd.de.mobile.api+json'));
   

5. Add Postfields

   curl_setopt($ch, CURLOPT_POSTFIELDS, $postfields[0]);
   

It's not the cleanest solution at all so please use it with care. But at least it works.