Show WordPress RSS Feed with Shortcode. E.g. [show_rss_feed url="https://maheshwaghmare.com/feed/"]

rss-feed-shortcode.php

<?php
/**
 * Show RSS feed with Shortcode.
 *
 * @example 	[show_rss_feed url="https://maheshwaghmare.com/feed/"]
 * 
 * @todo Change the `prefix_` and with your own unique prefix.
 * 
 * @since 1.0.0
 */
if( ! function_exists( 'prefix_show_rss_feed' ) ) :
	function prefix_show_rss_feed( $atts, $content ) {
		$atts = shortcode_atts( array(
			'url' => ''
		), $atts );

		// Missing URL.
		if( empty( $atts['url'] ) ) {
			return 'ERROR: Feed URL is missing.';
		}

		// Fetch RSS feeds.
		$rss = fetch_feed( $atts['url'] );

		// Fetching error.
		if ( is_wp_error( $rss ) ) {
			return 'ERROR: ' . $rss->get_error_message();
		}

		// Quantity error.
		if ( ! $rss->get_item_quantity() ) {
			$rss->__destruct();
			unset( $rss );
			return '<ul><li>An error has occurred, which probably means the feed is down. Try again later.</li></ul>';
		}

		// Return feed list.
		$output = '<ul>';
		foreach ( $rss->get_items() as $item ) {
			$link = $item->get_link();
			$link = esc_url( strip_tags( $link ) );

			$title = esc_html( trim( strip_tags( $item->get_title() ) ) );
			if ( empty( $title ) ) {
				$title = 'Untitled';
			}

			if ( '' === $link ) {
				$output .= "<li>$title</li>";
			} else {
				$output .= "<li><a href='$link'>$title</a></li>";
			}
		}
		$output .= '</ul>';
		$rss->__destruct();
		unset( $rss );
		
		return $output;
   }
   add_shortcode( 'show_rss_feed', 'prefix_show_rss_feed' );
endif;