CURLOPT_POST vs. CURLOPT_POSTFIELDS: Is CURLOPT_POST option required? - php

Question

I'm new to cURL in PHP. I have a question regarding usage of curl options.
Consider two script files: test1.php and test2.php both present in root www. I'm using Ubuntu 12.04 LTS. The libcurl version for PHP is 7.22.0.
Contents of test1.php
<?php
$ch = curl_init();
$post_data = array(
'firstname' => 'John',
'lastname' => 'Doe'
);
curl_setopt($ch, CURLOPT_URL, 'localhost/test2.php');
curl_setopt($ch, CURLOPT_POST, TRUE); //is it optional?
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);
curl_exec($ch);
curl_close($ch);
?>
Contents of test2.php
<?php
var_dump($_POST);
?>
When I execute test1.php via browser, I can see results posted. Now if I remove curl option containing CURLOPT_POST, the example still works. Even if I set CURLOPT_POST to false, post is performed and result is displayed. So, is that CURLOPT_POST not required at all? It looks option CURLOPT_POSTFIELDS takes care of sending data via POST without use of CURLOPT_POST option. When I print $_SERVER in test2.php, request method is always set to POST (with or without option CURLOPT_POST).
Could anyone please let me know the exact use of CURLOPT_POST option? Is it neccessary required for sending data via POST?

Answer 1

You are correct. CURLOPT_POSTFIELDS implies CURLOPT_POST. You don't need to use CURLOPT_POST while using CURLOPT_POSTFIELDS. The request method will always be set to POST in this case.
Note that this is in your case as long as you want it to be a POST request.
If you don't want to be it a POST request but set CURLOPT_POSTFIELDS, please see this related Q&A:
How to switch from POST to GET in PHP CURL

Answer 2

For future reference the API document say this about CURLOPT_POST
Summary:
A true parameter tells the library to do a regular HTTP post. This will also make the library use the a "Content-Type: application/x-www-form-urlencoded" header. (This is by far the most commonly used POST method).
Use the CURLOPT_POSTFIELDS option to specify what data to post and CURLOPT_POSTFIELDSIZE to set the data size. Optionally, you can provide data to POST using the CURLOPT_READFUNCTION and CURLOPT_READDATA options.
You can override the default POST Content-Type: header by setting your own with CURLOPT_HTTPHEADER.
Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header. You can disable this header with CURLOPT_HTTPHEADER as usual.
If you use POST to a HTTP 1.1 server, you can send data without knowing the size before starting the POST if you use chunked encoding. You enable this by adding a header like "Transfer-Encoding: chunked" with CURLOPT_HTTPHEADER. With HTTP 1.0 or without chunked transfer, you must specify the size in the request.
if you have issued a POST request and want to make a HEAD or GET instead, you must explicitly pick the new request type using CURLOPT_NOBODY or CURLOPT_HTTPGET or similar.
I'm testing right now whether setting the CURLOPT_POST to try will override my CURLOPT_HTTPHEADER, "Content-Type: application/json; charset=utf-8" setting.