Challenge 1 — Solution

Task: Write a jsonResponse() helper function (as shown in the chapter),
then write a small script simulating a "user not found" scenario: it
should call jsonResponse(['error' => 'User not found'], 404). Explain
in a comment why setting the status code AND the Content-Type header
both matter, even though the JSON body itself is valid either way.

<?php
    function jsonResponse($data, int $statusCode = 200) {
        http_response_code($statusCode);
        header('Content-Type: application/json');
        echo json_encode($data);
        exit;
    }

    // Simulating a "user not found" scenario
    jsonResponse(['error' => 'User not found'], 404);

    // Why both the status code and Content-Type header matter, even
    // though the JSON body itself is valid either way:
    //
    // The status code (404 here) is what a client application actually
    // checks PROGRAMMATICALLY to decide how to react - retry the
    // request, show a specific "not found" UI state, or treat it as a
    // genuine success. A client that only looked at the JSON body
    // would need to parse it first just to discover something went
    // wrong, which defeats much of the purpose of having status codes
    // in the first place (this chapter's own warn-box). Content-Type:
    // application/json matters separately - it tells the client HOW to
    // interpret the raw response bytes. Without it, some HTTP clients
    // might not automatically parse the body as JSON at all, treating
    // it as plain text instead - the body's own content being valid
    // JSON doesn't help if the client never attempts to parse it as
    // JSON to begin with.
?>


Output:
{"error":"User not found"}

(sent with a real 404 HTTP status code and a Content-Type:
application/json response header, both invisible in the raw echoed
text above but genuinely present in the actual HTTP response)

Notes:
- http_response_code($statusCode) must be called before header() and
  echo, since HTTP status codes and headers are both part of the
  response's own header section, which must be sent before the body.
- exit immediately after echoing the JSON prevents any further script
  output (e.g. from other error-handling code) from accidentally
  appending non-JSON text after the response body.
- This exact jsonResponse() function is directly reused, unchanged,
  by the chapter's own PostApiController example - demonstrating it's
  a genuinely reusable helper, not tied to any one specific endpoint.