CURLOPT_POST vs CURLOPT_CUSTOMREQUEST

Question

I am using the Email on Acid API.

While sending POST requests to the endpoint http://sandbox.emailonacid.com/v4/GetClientList through PHP Curl, I tried the following alternatives :

1. curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST")
2. curl_setopt($ch, CURLOPT_POST, 1);

The first option works, but the second option returns an HTTP 400 Bad Request.

Can anyone explain the behavior?

Answer 1

By default CURLOPT_POST will perform a regular POST request using a Content-Type header of "application/x-www-form-urlencoded" which is typically the kind used when submitting HTML forms.

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The API you're consuming has restricted Accept headers for application/json or application/xml depending on whether your sending a JSON or XML payload.

You can override the default Content-Type for a regular POST header using:

$headers = ['Content-Type: application/json'];
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);