Object of class CURLFile could not be converted to string - php

Question

How to achieve an image upload via cURL?
I am using a sandbox api for convert pdf file to .txt file. If i use "https://s3.amazonaws.com/sample.pdf" path of pdf for $sourceFile variable then its working fine. But if i use system path "test.pdf" then it's not working.
I was trying to through curl_file_create, but it gives the following error:
Recoverable fatal error: Object of class CURLFile could not be
converted to string in line.
I am using PHP Version 7.3.0
<?php
error_reporting(E_ALL);
$endpoint = "https://api.xxx.com/v1/jobs";
$apiKey = "GiVU******FR48H";
$sourceFile = "https://s3.amazonaws.com/sample.pdf";//new CurlFile("test.pdf");
$targetFormat = "txt";
$postData = array(
"source_file" => $sourceFile,
"target_format" => $targetFormat
);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $endpoint);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
curl_setopt($ch, CURLOPT_SAFE_UPLOAD, false);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_USERPWD, $apiKey . ":");
$body = curl_exec($ch);
curl_close($ch);
$response = json_decode($body, true);
echo "Response:\n---------\n";
echo"<pre>";
print_r($response);
?>
Response: ---------
Array
(
[id] => 8442473
[key] => GiVU******FR48H
[status] => initialising
[sandbox] =>
[created_at] => 2019-11-12T10:35:01Z
[finished_at] =>
[import] => Array
(
[id] => 671784
[url] => https://s3.amazonaws.com/sample.pdf
[status] => initialising
)
[target_files] => Array
(
)
[target_format] => txt
[credit_cost] => 0
)
Above example give me output as fine as well. If i replace amazonaws from system path then it doesn't gives any response.

Answer 1

CURLOPT_SAFE_UPLOAD is always set to false and curl expects files to be passed as string (#/path/to/file) because of it. In your case the code sends files as objects because it's using curl_file_create() when available.
When CURLOPT_SAFE_UPLOAD is set to false, you should not use curl_file_create() (it's flag for backwards compatibility).
Also, try to set CURLOPT_POSTFIELDS after CURLOPT_SAFE_UPLOAD (see here why).
PHP 5.x is not supported anymore and I suggest to get rid of the old syntax (#/path/to/file and CURLOPT_SAFE_UPLOAD = false) and always use curl_file_create().