The Ultimate Guide to WordPress REST API for Beginners

WordPress web development company uses REST API when connecting WordPress websites with other applications. It’s a built-in feature of the WordPress platform that extends functionality and streamlines business operations. 

In addition, when hiring a WordPress developer, provide the requirements to connect the site with the internal system. Then, WordPress REST API gets used. But the question comes, what exactly is a REST API in WordPress? 

And, if you are finding the answer to it, then you landed at the correct place. Let’s get started with understanding WordPress REST API. 

What is an API? 

Application Programming Interface (API) connects third-party applications and software. You can treat it as a software piece, aiding in exposing the functionality and data of a third-party app. 

Most applications utilize an API to streamline operations and build smooth communication between multiple stakeholders. Everything gets executed using an application programming interface, from viewing a YouTube video to seeing live updates.  Let’s look at an example for better understanding. 

Airlines ticket prices and availability are updated on a travel agency website as soon as someone books a ticket. However, it doesn’t matter from which website the ticket has been booked; the data get updated on every site selling that specific airline ticket. In such cases, API gets used. Every travel agency connects to the airline firm’s database through API. When someone books a ticket, the update first goes to the airline’s database, and from there, the API fetches details for travel agencies. And then, the fetched data gets displayed on the site. 

A Brief Overview to WordPress REST API and Why it Gets Used

When it comes to connecting WordPress to some external application, REST API comes into play. Representational State Transfer API provides an interface and guidelines to connect software. And you will see every WordPress web development company using it to integrate with external systems. 

When you use REST API for connecting WordPress to an external site, it allows sending and receiving data in JSON format. Moreover, the WordPress block editor – Gutenberg executes REST API functions in the backend. It updates the database simultaneously as you create and edit a new block. Firstly, the WordPress REST API was introduced as a plugin. But, later on, with the release of version 4.7, it gets added to the platform’s core. 

Furthermore, REST API in WordPress gets mostly used when a developer needs an external site built using a language other than PHP to access WordPress content. Additionally, any application that executes HTTP requests and understands JSON can connect with WordPress through REST API. 

One of the significant reasons behind using REST API is its ease of learning and implementation. Also, when you hire a WordPress developer, you can expect them to know REST API implementation.

How To Use the WordPress REST API?

To understand the working of REST API, you need to first understand the request, response, and endpoint terms. In addition, you must also learn about the methods used by it. 

When an application needs to access or retrieve data, it sends a request to the REST API. Then, the API authenticates that request, and if everything seems correct, it sends back the requested data as a response. However, if it encounters an error, you receive an error message as a response. 

Further, to use an API, you need to define an endpoint, which contains the URL, routing towards the resource or data you need. 

Additionally, the endpoint also uses REST API methods with URLs to define the action. With the help of methods, you tell the API whether you need to retrieve, store or delete data. When you write commands for REST API, the following methods will get used: 

• GET method can fetch/retrieve data from an external source. 
• PUT method enables to modify the data available on the server. 
• POST method gets used to store new data in the server/database. 
• DELETE method allows the removal of particular data available on the server. 

Now you know about the REST API methods, it’s time to test their working. To understand the REST API’s working, the simplest way is through the command line. If you use a Windows system, then access the Command Line Interface, and in the case of Linux and macOS, open the Terminal. Also, you would be using a cURL or WP-CLI tool for communicating with the WordPress website through the command line. 

Once you install any of the command line tools, establish a communication channel with the website using SSH (Secure Shell) protocol. After successfully connecting with the WordPress site, it’s time to send API requests. 

In the example, we would use the following URL as the primary route. 

http://yourwebsite.com/wp-json/

Using the REST API GET Method: 

To retrieve a webpage from the WordPress website, you need to execute the below-provided command on the CLI. However, the domain and path to the webpage will change as per your site configuration. 

GET http://yourwebsite.com/wp-json/wp/v2/pages

When you execute the command, it will retrieve all the web pages. But, if you want only a specific webpage, add its id at the end, just like the code below. 

GET http://yourwebsite.com/wp-json/wp/v2/pages/<id>

Using the REST API POST Method

If you want to add a blank webpage on the WordPress website, then below REST API command will aid you. 

POST http://yourwebsite.com/wp-json/wp-json/wp/v2/pages

Similarly, you can execute commands for PUT and DELETE methods. But, ensure that you are using a CLI tool and SSH session while performing all such operations.

Is There Anything Like Custom REST API in WordPress? 

No, there’s nothing like custom REST API in WordPress. But you can add custom endpoints for a REST API. It will help you connect WordPress to almost every service and mobile application without any significant complexities. 

To create a custom REST API endpoint, you only need to follow the below four steps:

Step 1: Generate a child theme and perform all operations upon it instead of the original site. 

Step 2: Define the route for your custom endpoint. 

Step 3: Configure a callback function for the custom endpoint

Step 4: Test the endpoint by executing GET, POST, PUT, and DELETE method commands. After successful customization, implement it to connect with external software and applications. 

Concluding Up

REST API gets heavily used when a developer must connect the WordPress site with external sources. It helps establish communication with third-party applications and allows fetching, storing, and deleting data. REST API primarily provides GET, POST, PUT, and DELETE methods, which can be used to fulfill all your requirements. 

Further, to use API, you need to set up a client who will send requests and a server to respond. Then, the client will send requests using the REST API method and URL route combination. As a result, data operations will get executed between the WordPress site and external applications.