Passing form variable into php curl request - php

Question

I've searched the site extensively and I just can't get the syntax correct in my attempt to replace a parameter in a Curl request with data inserted from a form.
This code works:
<?php
$curl = curl_init();
curl_setopt_array($curl, array(
CURLOPT_PORT => "8000",
CURLOPT_URL => "http://nd-337-495-552.rg-709-313.p2pify.com:8000",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "GET",
CURLOPT_POSTFIELDS => "{\"method\":\"liststreamitems\",\"params\":[\"Device\"],\"chain_name\":\"nw-504-042-6\"}",
CURLOPT_HTTPHEADER => array(
"Authorization: Basic abcdefghijklmnop1234567=",
"Content-Type: application/json",
"Postman-Token: dd629e44-26fb-4ed1-ac4e-c47faf38c356",
"cache-control: no-cache"
), // auth header content deliberately changed
));
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}
This code, where I try to replace "nw-504-042-6\" with the variable $ChainName in CURLOPT_POSTFIELDS does not work.
<?php
$ChainName = $_POST['ChainName'];
$StreamName = $_POST['StreamName'];
echo $ChainName;
$curl = curl_init();
curl_setopt_array($curl, array(
CURLOPT_PORT => "8000",
CURLOPT_URL => "http://nd-337-495-552.rg-709-313.p2pify.com:8000",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "GET",
CURLOPT_POSTFIELDS => "{\"method\":\"liststreamitems\",
\"params\":[\"Device\"],
\"chain_name\":"'"$ChainName"'"}",
CURLOPT_HTTPHEADER => array(
"Authorization: Basic abcdefghijklmnop1234567=",
"Postman-Token: 0bcbbec4-cc25-4059-b2c4-220c4722b9d5",
"cache-control: no-cache"
), // auth header content deliberately changed
));
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}
Would appreciate the assistance

Answer 1

Try to json_encode your params
$params = [
"method"=>"liststreamitems",
"params"=>["Device"],
"chain_name"=>$ChainName
];
Then pass it to the option CURLOPT_POSTFIELDS like this
CURLOPT_POSTFIELDS => json_encode($params);