Consume an External REST API from WordPress

There are loads of free, and paid-for, REST APIs out there that provide access to data and services. You can hook into these to build your own web-based apps. Learn how to add some code to your WordPress website to consume data from an external REST API, and then display it on your site.

For this tutorial, we’re going to pull some data from a public ipsum text generator API. Basically, it’s a free gobbledygook generator 😎 😎 😎

importantTo follow this tutorial, you’ll need to be using a custom child theme so you can edit your functions.php.

https://power-plugins.com/api/flipsum/ipsum/lorem-ipsum

Let’s Write some Code

In your custom child theme’s folder, create a file called shortcode-ipsum.php and paste the following into it.

<?php

/**
 * Flipsum Ipsum Shortcode
 *
 * https://wp-tutorials.tech/add-functionality/access-a-rest-api-from-wordpress/
 */

// If this file is called directly, abort.
defined('WPINC') || die();

const FIS_DEFAULT_IPSUM = 'lorem-ipsum';
const FIS_DEFAULT_PARAGRAPHS = 5;
const FIS_DEFAULT_ENABLE_DEBUG = false;

function do_shortcode_flipsum_ipsum($atts) {
	$html = '';

	if (is_admin() || wp_doing_ajax()) {
		// ...
	} else {
		// Parse the shortcode's options.
		$args = shortcode_atts(
			array(
				'ipsum' => FIS_DEFAULT_IPSUM,
				'paragraphs' => FIS_DEFAULT_PARAGRAPHS,
				'debug' => FIS_DEFAULT_ENABLE_DEBUG,
			),
			$atts
		);

		$url = sprintf(
			'https://power-plugins.com/api/flipsum/ipsum/%s?paragraphs=%d',
			urlencode($args['ipsum']),
			$args['paragraphs']
		);

		// Create a Curl Handle.
		$ch = curl_init();

		// Standard PHP/Curl options for a simple GET request.
		curl_setopt($ch, CURLOPT_URL, $url);
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

		// Execute the request.
		$json_response = curl_exec($ch);
		$response_code = intval(curl_getinfo($ch, CURLINFO_HTTP_CODE));

		// Close the Curl Handle.
		curl_close($ch);

		if ($response_code != 200) {
			$html .= sprintf('<p><strong>ERROR:</strong> Got HTTP response %d from the server.</p>', $response_code);
		} elseif (empty($json_response)) {
			// No data returned from the server.
			$html .= sprintf('<p><strong>ERROR:</strong> Empty respone from the server.</p>');
		} elseif (boolval($args['debug'])) {
			// Render the raw JSON response.
			$html .= '<pre>';
			$html .= sprintf("HTTP_RESPONSE=%d\n", $response_code);
			$html .= sprintf("%s", print_r(json_decode($json_response), true));
			$html .= '</pre>';
		} elseif (empty($ipsum_paragraphs = json_decode($json_response, true))) {
			$html .= sprintf(
				'<p><strong>ERROR:</strong> Failed to process the JSON response.</p><pre>%s</pre>',
				esc_html($json_response)
			);
		} else {
			// Loop through the paragraphs
			foreach ($ipsum_paragraphs as $ipsum_paragraph) {
				$html .= sprintf('<p>%s</p>', esc_html($ipsum_paragraph));
			}
		}
	}

	return $html;
}
add_shortcode('flipsum_ipsum', 'do_shortcode_flipsum_ipsum');

The logic is pretty straightforward. The main sequence breaks down like this:

1. Create a URL to access the Flipsum Ipsum API.
2. Create a Curl Handle ($ch)…
   1. Set some standard options.
   2. Execute the request.
   3. Store the result body (hopefully, a big string full of JSON data).
   4. Store the HTTP Response Code (hopefully 200=OK).
   5. Close the Curl Handle.
3. If the API returns nothing (an empty string) then set the returned HTML to an error string.
4. If we’ve passed debug=true in our shortcode parameters then set the returned HTML to the raw text returned by the API. Useful for debugging/testing.
5. If PHP can’t convert the API response into an array using json_decode() then return an error string AND the raw response, so we can figure out what the problem is.
6. Loop over the returned paragraphs and return the HTML to the frontend, with each paragraph wrapped in <p></p>.

Next, open your child theme’s functions.php and paste this into it.

// WP Tutorials : Flipsum Ipsum Shortcode
require_once dirname(__FILE__) . '/shortcode-ipsum.php';

In the block editor, create a shortcode block, enter [flipsum_ipsum], save your content and the view it. Boom! Instant nonsense for your website!

Shortcode Examples

Extending the Shortcode

This shortcode here is pretty basic, but works well enough. There are plenty of ways to extend it.

Cache the API Response in a Transient

To speed things up for your visitors, you might want to cache the API responses, so you don’t have to query the API for every request that comes to your site. You can store the gobbledygook in a WordPress transient – a short-lived data store that vanishes after a timeout (e.g. 1 hour or 1 day).

It could work something like this:

• The user wants some gobbledygook.
• Do we already have some gobbledygook in our transient?
  • If yes then…
    • Grab the gobbledygook from the transient.
  • Else…
    • Fetch some gobbledygook from the Flipsum Ipsum API.
    • Store the new gobbledygook in our transient with a timeout of 1 hour (or whatever you want).
• Render the gobbledygook.

The next time a user wants some gobbledygook, you can just use what’s in the transient, which will be much faster than calling the remote API every time.

Go forth and spread the gobbledygook 😎👍

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