How to fix null in CURLOPT_POSTFIELDS-CodePudding

I added $amount it started showing null

<?php

$api = $_GET['api'];
$amount = $_GET['amount'];

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => 'https://api.googl.com',
  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 =>'{
  "price_amount": $amount,
  "price_currency": "usd",
  "pay_currency": "btc"
}',
  CURLOPT_HTTPHEADER => array(
    'x-api-key:' . $api,
    'Content-Type: application/json'
  ),
));


$response = curl_exec($curl);

curl_close($curl);
header('Content-Type: application/json');
$json2 = json_encode(json_decode($response), JSON_PRETTY_PRINT);
echo $json2;

?>

CodePudding user response：

When you say "I added $amount it started showing null", could you please clarify? What exactly is showing null (what is "it")? More details are needed, but I can see one issue right off the bat--the following isn't going to work:

CURLOPT_POSTFIELDS =>'{
  "price_amount": $amount,
  "price_currency": "usd",
  "pay_currency": "btc"
}',

Strings created with single quotes (') do not parse PHP variables, only strings created with double quotes (") will parse variables. So in the example provided, the $amount variable there is just going to be the literal string "$amount", and not the value contained by the variable. However I would strongly urge you to not try and create this JSON string manually like this anyhow, instead create a PHP object/array that you want and use the json_encode() function to create the JSON string from that object.

Something like:

$myJsonObj = array(
  'price_amount' => $amount,
  'price_currency' => 'usd',
  'pay_currency' => 'btc'
);

And then:

CURLOPT_POSTFIELDS => json_encode($myJsonObj),