Web Services using the Slim Framework

Hello !

In this tutorial , you’ll find out how to create your own web service using the Slim Framework and why it’s important to create a web service.

Let’s get started !

if you are familiar with the web services terms , you can skip the definitions and start developing your first web service here .

What’s a web service ?

A web service is a secure way to offer the database data to other applications .I’d like to illustrate my point with an example : Imagine you have a database that contains many personal data of your users and you would like to give access to some data to other developers, How can you do it ?

Without the web services , you have to give the developers the database server address , the database login and password , then the developers will have full access to your database which is a bad solution !

💡 The solution is creating a web service that offers only the data needed , so the developers will not get your database credentials thus they will not have full access to your database .

You get the point .

Introduction to Slim Framework

Slim framework is a great PHP framework that will let you create your own web service without spending too much time .It’s open source and well documented .

 JSON

To put it simply , JSON is a text based format used to transmit data between two different apps . So , our data will be structured in a universal format in such a way that others apps will be able to process it easily .

Too much annoying details ? So let’s start developing our first web service .

Develop your web service 😎

1. Getting the data (JSON)

   First, we should define our route , in this example when we visit yourdomain/cars it will call the method ‘getCars’

$app->get('/cars','getCars'); 

Then we should define our ‘getCars’ method which will return all the cars contained in the Database .To do that , we have to write our Sql query

$sql = "SELECT manufacturer,color FROM car ORDER BY id";

Then , execute the query

$db = getDB();
$stmt = $db->query($sql);  
$cars = $stmt->fetchAll(PDO::FETCH_OBJ);

and finally return the data as JSON with this line of code

echo '{"Cars": ' . json_encode($cars) . '}';

The ‘getCars’ method will be :

function getCars() {
	$sql = "SELECT manufacturer,color FROM car ORDER BY id";
	try {
		$db = getDB();
		$stmt = $db->query($sql);  
		$cars = $stmt->fetchAll(PDO::FETCH_OBJ);
		$db = null;
		echo '{"Cars": ' . json_encode($cars) . '}';
	} catch(PDOException $e) {
	    echo "Error !"; 
	}
}

Let’s test it ! go to the browser and visit yourdomain/cars , it will show you this

{"Cars": [{"manufacturer":"Volkswagen","color":"Black"},{"manufacturer":"BMW","color":"Grey"},{"manufacturer":"Audi","color":"White"}]}

1. Insert data

To insert data to the database , we’ll use the HTTP POST method .We should first define the route

$app->post('/newcar', 'addCar');

Then we should define our ‘addCar’ method. In this method we will start first by getting the parameters sent by the POST method

 $manufacturer = $req->params('manufacturer'); 
 $color = $req->params('color'); 

Then write our Sql query

 $sql = "INSERT INTO car (`manufacturer`,`color`) VALUES (:manufacturer, :color);";

And finally , execute the query

$db = getDB();
$stmt = $db->prepare($sql);
    
$stmt->bindParam("manufacturer", $manufacturer);
$stmt->bindParam("color",$color);
 
$stmt->execute();

So , our ‘addCar’ method will be

function addCar() {
    global $app;
    $req = $app->request(); 
    
    $manufacturer = $req->params('manufacturer'); 
    $color = $req->params('color'); 
    
  $sql = "INSERT INTO car (`manufacturer`,`color`) VALUES (:manufacturer, :color);";
  
  try {
    $db = getDB();
    $stmt = $db->prepare($sql);
    
      $stmt->bindParam("manufacturer", $manufacturer);
      $stmt->bindParam("color",$color);
 
      $stmt->execute();
      $db = null;
  } catch(PDOException $e) {
      echo "Error !";
  }
}

To test , run this command in your terminal (cmd.exe if you are using Windows)

curl --data "manufacturer=Mercedes&color=Black"  http://localhost/WebService-SlimFramework/webservice.php/newcar

🎉 Congratulations  ! the data was successfully added to the database

To conclude

Slim framework is a robust and secure micro framework that you can use for many projects that needs to connect to databases. It’s a framework that keeps getting better day after day , I hope that you liked it.
Thank you for following the tutorial , I hope you enjoyed it  . Keep in touch to see my next tutorials

To download the full source code visit my Github repository here