Accessing a json api with php - php

Question

I'm trying to learn how I can interface with a json api.
In the documentation they give me a curl example:
If I run this as a command it works fine, gives me my data in a json format.
I thought I was on the right track with this: PHP + curl, HTTP POST sample code?
but apparently not as I can't figure out what to do with the -H portion of this command.
curl -H "APIKey:My:ApI;key;" -H "Content-Type:.../json" "https://urlofapp.com/API/GetTransaction" -d "{ 'CustomerID':'12345','EndDate':'2018-12-31','StartDate':'2018-01-01'}" > test.json
Trying to get the result into an array that I can sum and show a total of their orders for the year.
From the link I provided above I was trying to start with this:
// set post fields
$post = [
'CustomerID' => 12345,
'StartDate' => 2018-01-01,
'EndDate' => 2018-12-31,
];
$ch = curl_init('https://urlofapp.com/API/GetTransaction');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
// execute!
$response = curl_exec($ch);
// close the connection, release resources used
curl_close($ch);
// do anything you want with your response
var_dump($response);

Answer 1

The -h command refers the header.
Try below code,
// Generated by curl-to-PHP: http://incarnate.github.io/curl-to-php/
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://urlofapp.com/API/GetTransaction');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, "{ 'CustomerID':'12345','EndDate':'2018-12-31','StartDate':'2018-01-01'}");
curl_setopt($ch, CURLOPT_POST, 1);
$headers = array();
$headers[] = 'Apikey: My:ApI;key;';
$headers[] = 'Content-Type: application/json';
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
$result = curl_exec($ch);
if (curl_errno($ch)) {
echo 'Error:' . curl_error($ch);
}
curl_close ($ch);
I used below to convert the curl command to PHP script,
https://incarnate.github.io/curl-to-php/
Hope it would be useful.

Answer 2

Dealing with curl directly usually ends up being a pain. There are a number of libraries that can help making calls like that much simpler.
Here are a few:
Simple and straighforward: http://requests.ryanmccue.info/
Has everything you could ever possibly want: https://github.com/guzzle/guzzle