Pulling a base64 encoded string from http request in php - php

Question

Background
I wrote a small test to make sure I could pull the data from a POST request made from my mobile application. It works fine,
$rawJsonObj = file_get_contents('php://input');
$json = json_decode( $rawJsonObj, true );
$decodedData = base64_decode($json['data']);
file_put_contents('student-data/'.$json['username'].'.txt', $decodedData);
Then in my Slim Framework app I try the same logic and the actual data that I use to create the file with is null. But I can still access the username and password that are sent in the request.
$app->post('/api/v1/endpoint', function ($request, $response, $args) {
$rawJsonObj = $request->getParams();
$json = json_decode( $rawJsonObj, true );
$decodedData = base64_decode($json['data']);
file_put_contents('test.txt', $decodedData);
return $response;
}
The username and password are showing in the request and I can see them when I write the data in the request to a file.
$data = $request->getParams();
file_put_contents('2.txt', $data);
Data that is wrote to file,
","username":"myuname","password":"myPword"}
But the base64encoded string is missing,
Example
In Swift I am creating the dict like this, then POST it as json,
let dict: [String: Any] = [
"username": named,
"password": password,
"data": data.base64EncodedString()
]
if let json = try? JSONSerialization.data(withJSONObject: dict, options: []) {
request.httpBody = json
}
Question
How do I access the actual "data": data.base64EncodedString() from the request body in Slim Framework 3?
I assume this has to do with the way $rawJsonObj = file_get_contents('php://input'); actually handles the data compared to Slim?

Answer 1

Request::getParams() is a custom method by Slim (not part of PSR-7) that collects all input data; in other words, it's a rough equivalent of PHP's $_REQUEST superglobal. Internally, it grabs the request body with Request::getParsedBody() (this one, part of PSR-7). Here's where major differences with $_REQUEST or $_POST arise:
If the request Content-Type is either
application/x-www-form-urlencoded or multipart/form-data, and the
request method is POST, this method MUST return the contents of
$_POST.
Otherwise, this method may return any results of deserializing the
request body content; as parsing returns structured content, the
potential types MUST be arrays or objects only. A null value
indicates the absence of body content.
While $_POST only decodes standard form encodings (thus in your test code you need to fetch and parse data manually) getParsedBody() tries to decode other encodings but, just like $_POST, it needs a proper Content-Type to do so. If you send one from your mobile app:
Content-Type: application/json
... it'll work as expected because Slim has a builtin JSON decoder.
If you can't send an encoding declaration, you need to decode stuff manually. In this case, the PSR-7 way to fetch the raw request body is Message::getBody(), that returns a stream (more specifically, a Stream object that that implements StreamInterface).