What is api in php with example

Simple REST API With PHP MySQL (Step-by-Step Example)

Welcome to a tutorial and example on how to create a simple REST API in PHP and MYSQL. The term “REST API” probably sounds intimidating to some beginners, but in actual fact, it is something really simple.

In layman’s terms, a REST API is nothing but a service endpoint. It simply accepts a user request, processes it, and responds with the results. For example, we send $_POST[«email»]=»jon@doe.com» and $_POST[«password»]=»123456″ to https://site.com/api/login/ . The system processes the login request and replies OK .

Yep, that’s all. Read on for a detailed example!

TLDR – QUICK SLIDES

TABLE OF CONTENTS

REST API DEVELOPMENT

All right, let us now get into a simple example of creating a user API in PHP and MYSQL.

STEP 1) DUMMY USER DATABASE TABLE

CREATE TABLE `users` ( `user_id` bigint(20) NOT NULL, `user_email` varchar(255) NOT NULL, `user_password` varchar(255) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4; ALTER TABLE `users` ADD PRIMARY KEY (`user_id`), ADD UNIQUE KEY `user_email` (`user_email`); ALTER TABLE `users` MODIFY `user_id` bigint(20) NOT NULL AUTO_INCREMENT;

STEP 2) PHP USER LIBRARY

pdo = new PDO( "mysql:host=".DB_HOST.";dbname=".DB_NAME.";charset=".DB_CHARSET, DB_USER, DB_PASSWORD, [ PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC ]); > // (B) DESTRUCTOR - CLOSE DATABASE CONNECTION function __destruct () < if ($this->stmt!==null) < $this->stmt = null; > if ($this->pdo!==null) < $this->pdo = null; > > // (C) SUPPORT FUNCTION - SQL QUERY function query ($sql, $data) : void < $this->stmt = $this->pdo->prepare($sql); $this->stmt->execute($data); > // (D) CREATE/UPDATE USER function save ($email, $pass, $id=null) < $data = [$email, password_hash($pass, PASSWORD_BCRYPT)]; if ($id===null) < $this->query("INSERT INTO `users` (`user_email`, `user_password`) VALUES (. )", $data); > else < $data[] = $id; $this->query("UPDATE `users` SET `user_email`=?, `user_password`=? WHERE `user_id`=?", $data); > return true; > // (E) DELETE USER function del ($id) < $this->query("DELETE FROM `users` WHERE `user_id`=?", [$id]); return true; > // (F) GET USER function get ($id) < $this->query("SELECT * FROM `users` WHERE `user_".(is_numeric($id)?"id":"email")."`=?", [$id]); return $this->stmt->fetch(); > // (G) VERIFY USER (FOR LOGIN) function verify ($email, $pass) < // (G1) GET USER $user = $this->get($email); if (!is_array($user)) < return false; >// (G2) PASSWORD CHECK if (password_verify($pass, $user["user_password"])) < $_SESSION["user"] = [ "id" =>$user["user_id"], "email" => $user["user_email"] ]; return true; > else < return false; >> > // (H) DATABASE SETTINGS - CHANGE TO YOUR OWN! define("DB_HOST", "localhost"); define("DB_NAME", "test"); define("DB_CHARSET", "utf8mb4"); define("DB_USER", "root"); define("DB_PASSWORD", ""); // (I) START! session_start(); $USR = new Users();

• (A, B, I) When $USR = new Users() is created, the constructor will automatically connect to the database. The destructor closes the connection.
• (C) function query() is a helper function to run SQL queries.
• (D to G) There are only 4 functions, and all of them are essentially just SQL statements!
  • function save() Add a new user, or update an existing one.
  • function del() Delete a user.
  • function get() Get a user by ID or email.
  • function verify() Verify a given email and password (for login).

  STEP 3) API ENDPOINT

   exit(json_encode([ "status" => $status, "message" => $message, "more" => $more ])); > // (C) LOGIN CHECK function lcheck () < if (!isset($_SESSION["user"])) < respond(0, "Please sign in first", null, 403); >> // (D) HANDLE REQUEST if (isset($_POST["req"])) < switch ($_POST["req"]) < // (D1) BAD REQUEST default: respond(false, "Invalid request", null, null, 400); break; // (D2) SAVE USER case "save": lcheck(); $pass = $USR->save( $_POST["email"], $_POST["password"], isset($_POST["id"]) ? $_POST["id"] : null ); respond($pass, $pass?"OK":$USR->error); break; // (D3) DELETE USER case "del": lcheck(); $pass = $USR->del($_POST["id"]); respond($pass, $pass?"OK":$USR->error); break; // (D4) GET USER case "get": lcheck(); respond(true, "OK", $USR->get($_POST["id"])); break; // (D5) LOGIN case "in": // ALREADY SIGNED IN if (isset($_SESSION["user"])) < respond(true, "OK"); >// CREDENTIALS CHECK $pass = $USR->verify($_POST["email"], $_POST["password"]); respond($pass, $pass?"OK":"Invalid email/password"); break; // (D6) LOGOUT case "out": unset($_SESSION["user"]); respond(true, "OK"); break; >

  • Send a $_POST[«req»] to specify the request, followed by the required parameters.
  • For example – To add a new user, we send $_POST[«req»] = «save» , $_POST[«email»] = «jane@doe.com» , and $_POST[«password»] = «SECRET» to this endpoint.
  • The API will respond in a JSON encoded format – A status flag on the processing, and system message .

  STEP 4) API TESTING

  Actually, that’s all for the “complicated REST API”. But go ahead – POST a login request, add a new user, and update a new user. See for yourself how the API endpoint works.

  DOWNLOAD & NOTES

  Here is the download link to the example code, so you don’t have to copy-paste everything.

  SUPPORT

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  EXAMPLE CODE DOWNLOAD

  Click here for the source code on GitHub gist, just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

  EXTRA BITS & LINKS

  That’s it for the simple REST API example, and here are some small extras and links that may be useful to you.

  WHAT IS REST!? API!?

  • API – Application Programming Interface. In simple words, a software interface or service endpoint. That is, send your request and parameters to an API to do something.
  • REST – Representational State Transfer, a software architectural style. Basically, an API is considered to be REST if it:
    • Has a base URL (such as https://api.site.com/ ).
    • Uses the HTTP protocol.
    • Uses POST GET PUT .
    • Utilizes JSON XML .

    SO WHY BUILD AN API?

    

    Long story short, a single API can support all devices and platforms – Windows, Mac, iOS, Android, smartwatch, and more. Think of it in another way, an API is a system without a user interface.

    Yes, if you have not realized, the above is a fully functioning user system. All that’s left is to build the user interface on top – HTML, Andriod, iOS, it does not matter since the base system is already there.

    LINKS & REFERENCES

    INFOGRAPHIC CHEAT SHEET

    

    THE END

    Thank you for reading, and we have come to the end of this guide. I hope that it has given you some insight into creating your own API, and if you have anything to add to the guide, please feel free to comment below. Good luck and happy coding!

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