Invalid JSON payload received when sending request to FCM API - php

Question

I'm sending a request to FCM via my PHP app, but it returns the following error:
{
"code": 400,
"message": "Invalid JSON payload received.
Unknown name \"{\"validateOnly\":true,\"message\":{\"name\":\"testName\",\"token\":\"validToken\"}}\":
Cannot bind query parameter. Field '{\"validateOnly\":true,\"message\":{\"name\":\"testName\",\"token\":\"validToken\"}}'
could not be found in request message.",
"status": "INVALID_ARGUMENT",
"details": [ { "#type": "type.googleapis.com/google.rpc.BadRequest",
"fieldViolations": [
{ "description": "Invalid JSON payload received.
Unknown name \"{\"validateOnly\":true,\"message\":{\"name\":\"testName\",\"token\":\"validToken\"}}\":
Cannot bind query parameter.
Field '{\"validateOnly\":true,\"message\":{\"name\":\"testName\",\"token\":\"validToken\"}}' could not be found in request message."
} ] } ] } }
My notification
$notification = [
'validateOnly' => true,
'message' => [
'name' => $name,
'token' => "validToken"
]
];
$notification = json_encode($notification)
as JSON:
{
"validateOnly":true,
"message":{
"name":"testName",
"token":"validToken"
}
}
My http header
$header = [
'Accept' => 'application/json',
'Content-Length' => strlen($notification),
'Content-Type' => 'application/json',
];
$header = json_encode($header, JSON_UNESCAPED_SLASHES);
as JSON:
{
"Accept":"application/json",
"Content-Length":72,
"Content-Type":"application/json"
}
My cURL code
$curl_session = curl_init();
try {
curl_setopt($curl_session, CURLOPT_URL, $this->_apiUrl);
//_api_Url = https://fcm.googleapis.com/v1/projects/projectName/messages:send?access_token=$access_token
curl_setopt($curl_session, CURLOPT_POST, true);
curl_setopt($curl_session, CURLOPT_HTTPHEADER, $header);
curl_setopt($curl_session, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl_session, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl_session, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
curl_setopt($curl_session, CURLOPT_POSTFIELDS, $notification);
} catch (Exception $e) {
print_r($e);
}
$result = curl_exec($curl_session);
curl_close($curl_session);
My guess is that it's the first two quotes in \"{\"validateOnly\"... that's causing the issue.
Is that possible? If so, how do you suggest I fix it?
Any other ideas? As far as I can tell all my code is correct according to the HTTP v1 docs

Answer 1

Your headers are wrong. This is not how php-curl expects them and because of that your request content type will be the default application/x-www-form-urlencoded instead of seeing it as json. It should look like this:
$header = [
'Accept:application/json',
'Content-Length:'.strlen($notification),
'Content-Type:application/json',
];
curl_setopt($curl_session, CURLOPT_HTTPHEADER, $header);
and don't json encode it, just pass this to curl.
You can find this documented here: https://www.php.net/manual/en/function.curl-setopt.php
An array of HTTP header fields to set, in the format
array('Content-type: text/plain', 'Content-length: 100')