API with vanilla php

create.php

<?php

require_once "./config/db.php";

if ($_SERVER['REQUEST_METHOD'] === "POST") {
  //Make sure that the content type of the POST request has been set to application/json
  $contentType = isset($_SERVER["CONTENT_TYPE"]) ? trim($_SERVER["CONTENT_TYPE"]) : '';
  if (strcasecmp($contentType, 'application/json') != 0) {
    // throw new Exception('Content type must be: application/json');
    exit('Content type must be: application/json');
  }
  // receive json data
  $data = json_decode(file_get_contents('php://input'), true);

  //If json_decode failed, the JSON is invalid.
  if (!is_array($data)) {
    // throw new Exception('Received content contained invalid JSON!');
    exit('Received content contained invalid JSON!');
  }

  // insert data into database
  $sql = 'INSERT INTO feedback (email, summary, rating) VALUES (:email, :summary, :rating)';
  $stmt = $pdo->prepare($sql);
  $stmt->execute([
    'email' => $data['email'], 
    'summary' => $data['summary'], 
    'rating' => $data['rating']
  ]);
  header('Content-Type: application/json');
  echo json_encode([
    "success" => true,
    "message" => "Successfully submitted feedback"
  ]);
} else {
  echo "Sorry expected a POST request";
}

delete.php

<?php

require_once "./config/db.php";

if ($_SERVER['REQUEST_METHOD'] === "DELETE") {
  if(!isset($_GET["id"])) exit("Please pass feedback id as query");
  $id = $_GET["id"];
  // delete data from database
  $sql = 'DELETE FROM feedback WHERE id = :id';
  $stmt = $pdo->prepare($sql);
  $stmt->execute([
    'id' => $id
  ]);
  header('Content-Type: application/json');
  echo json_encode([
    "success" => true,
    "message" => "Successfully deleted feedback"
  ]);
} else {
  echo "Sorry expected a DELETE request";
}

index.php

<?php

require_once "./config/db.php";

if ($_SERVER['REQUEST_METHOD'] === "GET") {
  // Handle GET request
  $result = null;
  if(isset($_GET["id"])) {
    $id = $_GET['id'];
    $sql = 'SELECT * FROM feedback WHERE id = ?';
    $stmt = $pdo->prepare($sql);
    $stmt->execute([$id]);
    $result = $stmt->fetchObject();
  } else {
    $sql = 'SELECT * FROM feedback';
    $stmt = $pdo->query($sql);
    $result = $stmt->fetchAll();
  }
  header('Content-Type: application/json');
  echo json_encode($result);
} else {
  echo "Sorry expected a GET request";
}

update.php

<?php

require_once "./config/db.php";

if ($_SERVER['REQUEST_METHOD'] === "PUT") {
  //Make sure that the content type of the POST request has been set to application/json
  $contentType = isset($_SERVER["CONTENT_TYPE"]) ? trim($_SERVER["CONTENT_TYPE"]) : '';
  if (strcasecmp($contentType, 'application/json') != 0) {
    // throw new Exception('Content type must be: application/json');
    exit('Content type must be: application/json');
  }
  // receive json data
  $data = json_decode(file_get_contents('php://input'), true);

  //If json_decode failed, the JSON is invalid.
  if (!is_array($data)) {
    // throw new Exception('Received content contained invalid JSON!');
    exit('Received content contained invalid JSON!');
  }

  // insert data into database
  $sql = 'UPDATE feedback SET summary = :summary, email = :email WHERE id = :id';
  $stmt = $pdo->prepare($sql);
  $stmt->execute([
    'email' => $data['email'], 
    'summary' => $data['summary'], 
    'id' => $data['id']
  ]);
  header('Content-Type: application/json');
  echo json_encode([
    "success" => true,
    "message" => "Successfully udpated feedback"
  ]);
} else {
  echo "Sorry expected an PUT request";
}