PHP
JSON response format
Write a consistent JSON format for success and error responses.
The JsonResponse class
A REST API needs a consistent response format. The JsonResponse class provides it: it holds a status code (200, 201, 400, 404) and a body array. The send() method does three things: it sets the status code with http_response_code(), the content type with header(), and returns the body as structured data through json_encode().
Every handler then produces the same shape, so the client can parse it without trouble.
Status codes
HTTP status codes carry the meaning of a response. 200 means success, 201 created, 400 bad request and 404 not found. The JsonResponse constructor takes this code as its first parameter.
A successful read returns 200, creating a new record returns 201. Missing or broken requests answer with 400, a non-existent resource with 404. The client reads the outcome from the code alone.
Exercise Define the JsonResponse class
Define a class named JsonResponse. Add two properties: public int $status; and public array $body;. Add a __construct(int $status, array $body) that assigns them. Write a send() method that calls http_response_code($this->status) and header("Content-Type: application/json"), then returns return json_encode($this->body, JSON_UNESCAPED_UNICODE);. The demo creates an instance and prints the send() output.
Show example solution
application/json"); return json_encode($this->body, JSON_UNESCAPED_UNICODE);
Example solution:
<?php
// REST API project: Router + addRoute + dispatch + JsonResponse
class Router {
public array $routes = [];
public function addRoute(string $method, string $path, $handler): void {
$this->routes[] = ["method" => $method, "path" => $path, "handler" => $handler];
}
public function dispatch(string $method, string $path) {
foreach ($this->routes as $route) {
if ($route["method"] === $method && $route["path"] === $path) {
return ($route["handler"])();
}
}
return "404 Not Found";
}
}
class JsonResponse {
public int $status;
public array $body;
public function __construct(int $status, array $body) {
$this->status = $status;
$this->body = $body;
}
public function send(): string {
http_response_code($this->status);
header("Content-Type: application/json");
return json_encode($this->body, JSON_UNESCAPED_UNICODE);
}
}
// Demo:
$resp = new JsonResponse(200, ["message" => "OK"]);
echo $resp->send();
Test yourself
-
Which three tools does JsonResponse::send() use, in order?
- echo, print and var_dump
- count, sort and array_map
- fopen, fwrite and fclose
- http_response_code, header and json_encode
Show answer
http_response_code, header and json_encode — Correct. send() sets the status code, then the header, then encodes the body as structured data.
-
Match the status codes
- 200
- Success
- 201
- Created
- 400
- Bad request
- 404
- Not found
-
Complete the content type header
header("____");
Show answer
header("Content-Type: application/json");
Next lesson: Project final - REST API
