Trouble with Param arguments for an Api - php

Question

Im trying to get all cities of a specific country from an API(https://countriesnow.space/). Im using Php and curl but the result says:
{
"error": true,
"msg": "missing param (country)"
}
Im using a script which is given by but it does not work: https://documenter.getpostman.com/view/1134062/T1LJjU52#4829d16f-0f4e-43ec-886e-68ebad1221d8
<?php
$curl = curl_init();
curl_setopt_array($curl, array(
CURLOPT_URL => 'https://countriesnow.space/api/v0.1/countries/cities',
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => '',
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 0,
CURLOPT_FOLLOWLOCATION => true,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => 'POST',
CURLOPT_POSTFIELDS =>'{
"country": "nigeria"
}',
));
$response = curl_exec($curl);
curl_close($curl);
echo $response;
Could anyone tell me whats wrong here? Really cant tell whats the issue.

Answer 1

cURL will automatically set the Content-Type to application/x-www-form-urlencoded, when you pass a string value for CURLOPT_POSTFIELDS.
But this is not supposed to be form data, but JSON. Add
CURLOPT_HTTPHEADER => ['Content-Type: application/json']
to your cURL options, to let the API know you are in fact sending JSON.