PHP, API vk.com - how to upload photos to the wall?

Question

PHP

3 days trying to upload an image to VK.
I follow the manual https://vk.com/dev/upload_files
1. I get the url to upload the image
file_get_contents(' https://api.vk.com/method/photos.getWallUploadServ... '.$access_token);
2. I send a post to the received url
$img_src = '4.png';
$imgbinary = fread(fopen($img_src, "r"), filesize($img_src));
$img_str = base64_encode($imgbinary);
$post_params = array(
"file1" => $img_str,
);
file_get_contents(' https://api.vk.com/method/photos.getWallUploadServ... '.$access_token);
$dataArray=json_decode($data);
$ch = curl_init( $dataArray->
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch, CURLOPT_SSL_VERIFYHOST, false );
curl_setopt( $ch, CURLOPT_SSL_VERIFYPEER, false );
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_params);
$response = curl_exec( $ch );
curl_close( $ch );
print_r($response);
An empty photo parameter comes in the response
example response
{"server":606321,"photo":"[]","hash":"afc01d1f75f443b30ff7b49254f642e1"}
Tell me what's wrong.
In vk technical support, they answered like this
. We only support downloading a file directly, and not at an address. Those. in file1 you must pass the byte array of the photo.

Answer 1

1. The documentation says that the names of the POST fields are file1, file2,...,file5, and you have photo
2. An incorrect request for sending a file may be generated, try this:

$post_params = array(
    'file1' => '@'.$img_src,
);

Accordingly, the lines above

$imgbinary = fread(fopen($img_src, "r"), filesize($img_src));
$img_str = base64_encode($imgbinary);

you don't need