Why my GET function of my API REST doesnt return a

问题:

I'm using XAMPP with PhpMyAdmin to store my database and I'm trying to make an API REST, but I don't have good results. For that, I'm using Slim framework.

I put all Slim framework files in a folder named project inside /htdocs in the folder of xampp and I create my connect.php and my api.php files. I also change my index.php to use both files that I mentioned before.

I configurated my connect.php and index.php files and I created my GET method in the api.php file but, when I try to get the information that there is on the database I can't get any value.

Both files, I mean, connect.php and api.php are inside a folder named app and further they are in another folder named libs and routes respectively.

/project/app/libs/connect.php
/project/app/routes/api.php

I put here all the code I have:

index.php

<?php

  require 'Slim/Slim.php'; 

  \Slim\Slim::registerAutoloader();

  $app = new \Slim\Slim();

  define("SPECIALCONSTANT",true);

  require 'app/libs/connect.php';
  require 'app/routes/api.php';

  $app->run();

?>

connect.php

<?php
if(!defined("SPECIALCONSTANT")) die("Access denied");

function getConnection()
{
    try{
        $db_username = "root";
        $db_password = "";
        $connection = new PDO("mysql:host=localhost;dbname=project",$db_username,$db_password);
        $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    }catch(PDOException $e)
    {
        echo "Error: " . $e->getMessage();
    }

    return $connection;
}
?>

api.php

<?php
if(!defined("SPECIALCONSTANT")) die("Access denied");

$app->get("/users/",function() use($app)
{
    try{
        $connection = getConnection();
        $dbh = $connection->prepare("SELECT * FROM users");
        $dbh->execute();
        $users = $dbh->fetchAll();
        $connection = null;

        $app->response->headers->set("Content-type","application/json");
        $app->response->status(200);
        $app->response->body(json_encode($users));

    }catch(PDOException $e)
    {
        echo "Error: " . $e->getMessage();
    }
});

My database name is project and the table that I have in my database is named users. This database is hold on my phpmyadmin.

Then, I try to return the values that I have on this table with my get method putting in my url localhost/project/users/ but it doesn't work. I just saw a blank page and I saw on the Internet that it would have to give me the values that I have in my table.

I though that my problem could be on headers, status and body because I couldn't understand them very properly and I search them in the documentation but it didn't help me a lot. The pages that I search were:

http://docs.slimframework.com/response/headers/ http://docs.slimframework.com/response/status/ http://docs.slimframework.com/response/body/

So please if you can also add some info to clearify these concepts I will be so thankful with all of you.

I'm really new in API REST and I can't see my error (I'm using a tutorial). Why it doesn't work?

EDIT: I tried the proposal of Abdo Adel but it also didn't work. It gives to me the following error.

Details

Type: ErrorException
Code: 8
Message: Undefined variable: users
File: C:\xampp\htdocs\proyecto\app\routes\api.php
Line: 21 --> Here it's the line when I have echo sentence

Trace

0 C:\xampp\htdocs\project\app\routes\api.php(21): Slim\Slim::handleErrors(8, 'Undefined varia...', 'C:\\xampp\\htdocs...', 21, Array)
1 [internal function]: {closure}()
2 C:\xampp\htdocs\project\Slim\Route.php(468): call_user_func_array(Object(Closure), Array)
3 C:\xampp\htdocs\project\Slim\Slim.php(1357): Slim\Route->dispatch()
4 C:\xampp\htdocs\project\Slim\Middleware\Flash.php(85): Slim\Slim->call()
5 C:\xampp\htdocs\project\Slim\Middleware\MethodOverride.php(92): Slim\Middleware\Flash->call()
6 C:\xampp\htdocs\project\Slim\Middleware\PrettyExceptions.php(67): Slim\Middleware\MethodOverride->call()
7 C:\xampp\htdocs\project\Slim\Slim.php(1302): Slim\Middleware\PrettyExceptions->call()
8 C:\xampp\htdocs\project\index.php(19): Slim\Slim->run()
9 {main} 

EDIT2: Now I know that the problem it's on the json_encode because it gives me the error: JSON_ERROR_UTF8 when I use json_last_error(). By the moment I couldn't solve it.

回答1:

change

$app->response->headers->set("Content-type","application/json");
$app->response->status(200);
$app->response->body(json_encode($users));

to

header("HTTP/1.1 200");
header("Content-Type:application/json; charset=utf-8");
echo json_encode($users);