when CURLOPT_HTTPHEADER need 'Content-Length' - php

Question

I have this code in the client side of my application:
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "GET");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-Type: application/json',
'Content-Length:0 ' )
);
$body = curl_exec($ch);
while in the server files:
$ch = curl_init($this->modelAddress);
$data = array("params"=>array("resource" => "artist","operation" => $operation,"params"=>$params));
$data_string = json_encode($data);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-Type: application/json',
'Content-Length: ' . strlen($data_string))
);
They are made from 2 different people and I want to ask what is the most correct.
When the use of 'Content-Length:0' instead of 'Content-Length:'.strlen($data_string) is better.
It's only question of POST/GET method?
I've searched explanations of this in the web but I've found nothing

Answer 1

If you use http PUT with curl then you have to specify the Content-Length header. Otherwise it is automatically handled by the curl for both GET and POST.
For example if you are posting the following data with curl with CURLOPT_POSTFIELDS. Then curl will automatically add the length of the data with the header.
$data = "name=alex&email=none!";
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
For better understand, run your curl code using verbose mode and you'll see how its handling the requests and responses.
curl_setopt($ch, CURLOPT_VERBOSE, true);