PHP cURL how to send a JSON POST request and also include a URL querystring?

Question

I'm trying to submit a POST request with JSON data to an api endpoint. The endpoint requires a querystring passing the api credentials, but also requires the JSON data to be POSTed.

When I try to do this with PHP cURL as shown below, the querystring is apparently removed - thus the api is rejecting the request due to missing api key.

I can do this easily with Postman when testing access to the api endpoint.

How can I make the cURL request include both the querystring AND the JSON POST body?

Example code:

// $data is previously defined as an array of parameters and values.

$url = "https://api.endpoint.url?api_key=1234567890";

$ch = curl_init();
$json = json_encode($data);

curl_setopt($ch,CURLOPT_URL, $url);
curl_setopt($ch,CURLOPT_POST, true);
curl_setopt($ch,CURLOPT_POSTFIELDS, $json);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Content-Type: application/json',
    'Content-Length: ' . strlen($json)
] 

//execute post
$result = curl_exec($ch);

//close connection
curl_close($ch);

Answer 1

You are doing almost right.

Sometimes you need to relax SSL verification.
Otherwise, update php ca bundle:
https://docs.bolt.cm/3.7/howto/curl-ca-certificates

Add the following:

$headers = array(
  "Content-type: application/json;charset=UTF-8",
  "Accept-Encoding: gzip,deflate",
  "Content-length: ".strlen($json),
);

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_TIMEOUT, 300);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $json);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_ENCODING, "identity, deflate, gzip");
curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
curl_setopt($ch, CURLINFO_HEADER_OUT, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);

$result = curl_exec($ch);
$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

Sometimes you need to change encoding too:

$result = utf8_decode($result);

And check the returning data.