Question

Im trying to post to a multipart html form using CURLs CURLOPT_POSTFIELDS, but I cannot find out how to post it with no files.

When testing the form in normal browser, the “File” field can be empty, “Name” and “Message” can not.

This works:

$array = array(
 "Name" => "Jon",
 "Message" => "My package was broken, please send new.",
 "File" => "@look_omg_its_broken_omgomg_look_at_the_corners.jpg"
);
curl_setopt ($ch, CURLOPT_POSTFIELDS, $array);

This doesnt:

$array = array(
 "Name" => "Jon",
 "Message" => "My package was broken, please send new.",
 "File" => ""
);
curl_setopt ($ch, CURLOPT_POSTFIELDS, $array);
$output = curl_exec($ch);

This last $output results in a bool(false)
I have also tried these variations of values, but no success.

"File" => "@"
"File" => "@/"
"File" => NULL
"File"
"File" => array("")
"File" => array("filename" => "")

Anyone know better?

Answer 1

Without refactoring your backend or emulating a multi-part form submission manually I’m pretty sure you won’t be able to solve your problem with any CURLOPT_POSTFIELDS logic alone, also see:

• http_request_body_encode
• Generating multipart boundary
• userland multipart/form-data handler

If you insist on trying to solve this using CURL alone, I suggest you inspect the ext/curl source code.