PHP cause the page HTTP Error 500 (Internal Server Error): - php

Question

I have simple function in PHP that gives me
HTTP Error 500 (Internal Server Error):
When I comment it, the simple echo does get printed.
Here is the function:
error_reporting(E_ALL);
ini_set('display_errors', '1');
function invokeAuthenticationServiceAPI()
{
$json = <<<"JSON"
{
"auth":
{
"username":"foo",
"password":"bar"
}
}
JSON;
$data_string = json_decode($json);
echo $data_string;
/*
$ch = curl_init('https://apirestserverdemo/api');
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-Type: application/json',
'Content-Length: ' . strlen($data_string))
);
$result = curl_exec($ch);
echo $result;
*/
}
I call it in the HTML file like this:
<?php
invokeAuthenticationServiceAPI();
?>
As you can see, I need to send it to rest api server. But it does fail only on the string to json formatting.
I have two questions:
Maybe I have done something that php doesn't like. Ok, but can I get some kind of error message and not "Error 500 (Internal Server Error)"?
What am I doing wrong?

Answer 1

You should check the web-server error log for the details of the error, but judging by the code you have posted, the problem is probably that there are spaces before the end of the heredoc JSON; and the first time you use JSON it should not be quoted.
You should use this:
$json = <<<JSON
{
"auth":
{
"username":"foo",
"password":"bar"
}
}
JSON; // no spaces before JSON;
instead of this:
$json = <<<"JSON"
{
"auth":
{
"username":"foo",
"password":"bar"
}
}
JSON;
Although personally I would generate an array or object in php and use json_encode to generate the correct output.

Answer 2

Remove double quotes around JSON and remove extra spaces which invalidate the PHP heredoc syntax
$json = <<<"JSON"
should be
$json = <<<JSON
Like
<?php
$str = <<<JSON
{
"auth":
{
"username":"foo",
"password":"bar"
}
}
JSON;
echo $str;
?>

Answer 3

If you have a 500 Internal Server Error you almost certainly have a fatal error in PHP. Depending on your code you may find the error in your error logs or you may have to debug your code using for example xdebug.
You don't need quotes around JSON. Other than that there's nothing immediately wrong with your code. However you should generate JSON using json_encode.