PHP Rest API

What is PHP Rest API?

REST stands for “REpresentational State Transfer”. REST is an architectural style that defines a set of constraints for developing and consuming web services through the standard protocol (HTTP).

API stands for “Application Programming Interface”. It is a set of routines, protocols, and tools for creating software applications. An API interface makes communication possible between various software components.

REST API is the interface that allows mobile devices and web browsers (or also other web servers) to CRUD (create, read, update and delete) resources in the server respecting the REST rules (such as being stateless).

How Does REST API Work

REST requests are related to CRUD operations (Create, Read, Update, Delete) in the database, REST uses GET, POST, PUT and DELETE requests. Here below you can see what are the functions.

• GET — it is used to transfer data from client to server in HTTP protocol using URL String
• POST — it is also used to transfer data from client to server in HTTP protocol but it carries request parameters in the message body which makes it a more secure way
• PUT — This method request is used to enclosed the entity under the supplied Request URL.
• Options — It shows which technique is supportable.
• HEAD — It returns the meta-information.

Rest API Example

Let’s learn about REST API in PHP with the following example. Follow the below steps to create a simple REST API program in PHP using XAMPP on a local computer:

1). Create a database called “rest_api_php” from PHPMyAdmin

2). Once the database is created, run the following SQL command to create a table:

CREATE TABLE IF NOT EXISTS `order_transactions` (
`id` int(30) NOT NULL AUTO_INCREMENT,
`order_id` int(80) NOT NULL,
`amount` decimal(10,2) NOT NULL,
`response_code` int(10) NOT NULL,
`response_desc` varchar(80) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `order_id` (`order_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 ;

Once the table is created with the above command, add some dummy data.

3). Now, create a file called “database.php” inside the “inc” directory of your project root directory for setup database connection. Add the following code to the “database.php” file:

$conn = mysqli_connect("localhost","root","","allphptricks");
if (mysqli_connect_errno()){
echo "Failed to connect to MySQL: " . mysqli_connect_error();
die();
}

4). Now create an “index.php” file in the root directory of your project and add the following code

<?php
header("Content-Type:application/json");
if (isset($_GET['order_id']) && $_GET['order_id']!="")
{
    include('inc/database.php');
    $order_id = $_GET['order_id'];
    $result = mysqli_query(
    $conn,
    "SELECT * FROM `order_transactions` WHERE order_id=$order_id");
    if(mysqli_num_rows($result)>0){
    $row = mysqli_fetch_array($result);
    $amount = $row['amount'];
    $response_code = $row['response_code'];
    $response_desc = $row['response_desc'];
    response($order_id, $amount, $response_code,$response_desc);
    mysqli_close($conn);
    }
    else
    {
    response(NULL, NULL, 200,"No Record Found");
    }
}
else
{
    response(NULL, NULL, 400,"Invalid Request");
}
function response($order_id,$amount,$response_code,$response_desc){
    $response['order_id'] = $order_id;
    $response['amount'] = $amount;
    $response['response_code'] = $response_code;
    $response['response_desc'] = $response_desc;
    $json_response = json_encode($response);
    echo $json_response;
}

5). Your application is completed. Now, you will get order transaction-related data by running the following URL where “rest-api” is the name of the project root directory.

http://localhost/rest-api/?order_id=222

You will get output like the following:

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