Add more taxonomy options to the post navigation link

docs/reference-guides/core-blocks.md

@@ -639,7 +639,7 @@ Displays the next or previous post link that is adjacent to the current post. ([
 -	**Name:** core/post-navigation-link
 -	**Category:** theme
 -	**Supports:** color (background, link, text), typography (fontSize, lineHeight), ~~html~~, ~~reusable~~
--	**Attributes:** arrow, label, linkLabel, showTitle, textAlign, type
+-	**Attributes:** arrow, inSameTerm, label, linkLabel, showTitle, taxonomy, textAlign, type
 
 ## Post Template
 

packages/block-library/src/post-navigation-link/block.json

@@ -28,8 +28,16 @@
 		"arrow": {
 			"type": "string",
 			"default": "none"
+		},
+		"inSameTerm": {
+			"type": "boolean"
+		},
+		"taxonomy": {
+			"type": "string",
+			"default": ""
 		}
 	},
+	"usesContext": [ "postType" ],
 	"supports": {
 		"reusable": false,
 		"html": false,

packages/block-library/src/post-navigation-link/edit.js

@@ -10,6 +10,7 @@ import {
 	__experimentalToggleGroupControl as ToggleGroupControl,
 	__experimentalToggleGroupControlOption as ToggleGroupControlOption,
 	ToggleControl,
+	SelectControl,
 	PanelBody,
 } from '@wordpress/components';
 import {
@@ -20,9 +21,20 @@ import {
 	useBlockProps,
 } from '@wordpress/block-editor';
 import { __, _x } from '@wordpress/i18n';
+import { useSelect } from '@wordpress/data';
+import { store as coreStore } from '@wordpress/core-data';
 
 export default function PostNavigationLinkEdit( {
-	attributes: { type, label, showTitle, textAlign, linkLabel, arrow },
+	context: { postType },
+	attributes: {
+		type,
+		label,
+		showTitle,
+		textAlign,
+		linkLabel,
+		arrow,
+		taxonomy,
+	},
 	setAttributes,
 } ) {
 	const isNext = type === 'next';
@@ -47,6 +59,40 @@ export default function PostNavigationLinkEdit( {
 			[ `has-text-align-${ textAlign }` ]: textAlign,
 		} ),
 	} );
+
+	const taxonomies = useSelect(
+		( select ) => {
+			const { getTaxonomies } = select( coreStore );
+			const filteredTaxonomies = getTaxonomies( {
+				type: postType,
+				per_page: -1,
+				context: 'view',
+			} );
+			return filteredTaxonomies;
+		},
+		[ postType ]
+	);
+	const getTaxonomyOptions = () => {
+		const selectOption = {
+			label: __( 'Unfiltered' ),
+			value: '',
+		};
+		const taxonomyOptions = ( taxonomies ?? [] )
+			.filter(
+				( tax ) =>
+					tax.slug !== 'nav_menu' &&
+					tax.slug !== 'wp_pattern_category'
+			)
+			.map( ( item ) => {
+				return {
+					value: item.slug,
+					label: item.name,
+				};
+			} );
+
+		return [ selectOption, ...taxonomyOptions ];
+	};
+
 	return (
 		<>
 			<InspectorControls>
@@ -114,6 +160,22 @@ export default function PostNavigationLinkEdit( {
 					</ToggleGroupControl>
 				</PanelBody>
 			</InspectorControls>
+			<InspectorControls group="advanced">
+				<SelectControl
+					label={ __( 'Filter by taxonomy' ) }
+					value={ taxonomy }
+					options={ getTaxonomyOptions() }
+					onChange={ ( value ) =>
+						setAttributes( {
+							taxonomy: value,
+							inSameTerm: value === '' ? false : true,
+						} )
+					}
+					help={ __(
+						'Only link to posts that have the same taxonomy terms as the current post. For example the same tags or categories.'
+					) }
+				/>
+			</InspectorControls>
 			<BlockControls>
 				<AlignmentToolbar
 					value={ textAlign }

packages/block-library/src/post-navigation-link/index.php

@@ -99,10 +99,24 @@ function render_block_core_post_navigation_link( $attributes, $content ) {
 		}
 	}
 
-	// The dynamic portion of the function name, `$navigation_type`,
-	// refers to the type of adjacency, 'next' or 'previous'.
+	$in_same_term = isset( $attributes['inSameTerm'] ) ? $attributes['inSameTerm'] : false;
+	$taxonomy     = isset( $attributes['taxonomy'] ) && $in_same_term ? $attributes['taxonomy'] : '';
+
+	/**
+	 * The dynamic portion of the function name, `$navigation_type`,
+	 * Refers to the type of adjacency, 'next' or 'previous'.
+	 *
+	 * @See https://developer.wordpress.org/reference/functions/get_previous_post_link/
+	 * @See https://developer.wordpress.org/reference/functions/get_next_post_link/
+	 */
 	$get_link_function = "get_{$navigation_type}_post_link";
-	$content           = $get_link_function( $format, $link );
+
+	if ( $in_same_term ) {
+		$content = $get_link_function( $format, $link, $in_same_term, '', $taxonomy );
+	} else {
+		$content = $get_link_function( $format, $link );
+	}
+
 	return sprintf(
 		'<div %1$s>%2$s</div>',
 		$wrapper_attributes,

test/integration/fixtures/blocks/core__post-navigation-link.json

@@ -6,7 +6,8 @@
 			"type": "next",
 			"showTitle": false,
 			"linkLabel": false,
-			"arrow": "none"
+			"arrow": "none",
+			"taxonomy": ""
 		},
 		"innerBlocks": []
 	}