PHP cURL文件获取内容始终为空

Question

I've created an endpoint in Paw (and/or Postman) for handling file uploads. It works great!

It's pretty simple. And in my application I can do something like:

echo file_get_contents('php://input');

And it will print out an encoded representation of the image/file (a cute kitten).

The problem is, I cannot seem to reproduce this behaviour using just cURL (Current application uses Guzzle).

When I try something like:

$target_url = 'http://my-document-handling-service.net:8000/documents';

$request = curl_init($target_url);

curl_setopt($request, CURLOPT_POST, true);
curl_setopt($request, CURLOPT_RETURNTRANSFER, true);
curl_setopt($request, CURLOPT_POSTREDIR, 3);

curl_setopt(
    $request,
    CURLOPT_POSTFIELDS,
    array(
      'file' => '/Users/xxxxxxx-xxxx/Documents/kitten-test-upload-image-1.jpg'
    ));

echo curl_exec($request);

curl_close($request);

The body (file_get_contents()) is always empty. I don't really understand cURL I've always just used Guzzle - but now I have to use cURL and I can't get the body.

What am I doing wrong?

Answer 1

(too long for a comment, the existing answer is very close to being correct, albeit bugged and won't work, but doesn't say why your origianl code failed) - when you give CURLOPT_POSTFIELDS an array, it encodes the input in multipart/form-data-format, and PHP parses multipart/form-data into $_POST (and for file uploads, $_FILES), and empties php://input in the process (it does this for any encoding it has built-in support for, and as of writing, there are 2, application/x-www-form-urlencoded, andmultipart/form-data`), and your code

curl_setopt(
    $request,
    CURLOPT_POSTFIELDS,
    array(
      'file' => '/Users/xxxxxxx-xxxx/Documents/kitten-test-upload-image-1.jpg'
    ));

sends the variable file with the value '/Users/xxxxxxx-xxxx/Documents/kitten-test-upload-image-1.jpg' to the server in the multipart/form-data format, thus your value is actually in $_POST['file'], but if you want to send the raw image directly, no encoding, so you can use php://input on the target server, use CURLOPT_INFILE or CURLOPT_POSTFIELDS, for example

curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_INFILE,($fp=fopen('abc.txt','rb')));
curl_setopt($ch, CURLOPT_INFILESIZE,123);
(...)
curl_exec($ch);
fclose($fp);

or

curl_setopt($ch,CURLOPT_POSTFIELDS,file_get_contents("abc.txt"));
curl_setopt($ch,CURLOPT_HTTPHEADER,array('Content-Type: application/octet-stream'));
curl_exec($ch);

(note that the second method will use more ram, it will put the entire file in memory prior to uploading, while the first method will send the data in chunks, making it possible to upload any size files without running out of ram, unlike the second method)