PHP curl echo not displaying in browser - php

Question

I am trying to display the response string from a PHP POST request in the browser. If I run:
<?php
$project_id = "abcdefgh";
$session_id = "123456789";
$url = "https://dialogflow.googleapis.com/v2/projects/".$project_id."/agent/sessions/".$session_id.":detectIntent";
$query = '{
"query_input": {
"text": {
"text": "Test input",
"language_code": "en-US"
}
}
}';
//open connection
$ch = curl_init();
//set the url, number of POST vars, POST data
curl_setopt($ch,CURLOPT_URL, $url);
curl_setopt($ch,CURLOPT_POST, true);
curl_setopt($ch,CURLOPT_POSTFIELDS, $query);
//So that curl_exec returns the contents of the cURL; rather than echoing it
curl_setopt($ch,CURLOPT_RETURNTRANSFER, true);
//execute post
$result = curl_exec($ch);
echo $result;
curl_close($ch);
?>
in VSCode, I get the following response (this is expected behavior):
{
"error": {
"code": 401,
"message": "Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.",
"status": "UNAUTHENTICATED"
}
}
However, if I navigate to the index.php file running on my WAMP server in Chrome, I get a blank screen. I can echo other strings, such as:
I can even copy the response directly, and echo the response as a string in the browser. It just seems to not work with the post request (maybe it is a timing thing?). This could be a WAMP configuration/permissions problem, but I feel the problem might be elsewhere. Thanks for your help!

Answer 1

I had to download and add cacert.pem to my php.ini file and restart my WAMP server to get it to work. It was an error with the curl call.

Answer 2

Because your return is an object, you must access it by following its object chain. Unable to execute echo an object, you must retrieve the message attribute and return a string.
//execute post
$result = curl_exec($ch);
// Decode object ()
$result = json_decode($result);
// Message error
echo $result->error->message;
curl_close($ch);
Reference: Object