Breadcrumbs – PRC Platform

Displays a breadcrumb navigation trail showing the hierarchical path to the current page.

Block Metadata

Property	Value
Name	`prc-block/breadcrumbs`
Title	Breadcrumbs
Category	`theme`
Version	`1.0.0`
API	3
Textdomain	`breadcrumbs`
Example	Yes (separator, home/index crumbs — inserter preview)

Attributes

Attribute	Type	Default	Description
`contentJustification`	`string`	—	Horizontal alignment of the breadcrumb trail: `left`, `center`, or `right`.
`separator`	`string`	`">"`	The character displayed between breadcrumb items.
`showCurrentPageTitle`	`boolean`	`false`	Whether to display the current page as the last breadcrumb.
`showLeadingSeparator`	`boolean`	`false`	Whether to show a separator before the first breadcrumb item.
`showHome`	`boolean`	`true`	Whether to display the home crumb.
`homeCrumb`	`object`	—	Configuration for the home breadcrumb. Properties: `id`, `url`, `text`, `asIcon` (boolean). When `asIcon` is true the block renders a house icon.
`showIndex`	`boolean`	`true`	Whether to display the index/section crumb.
`indexCrumb`	`object`	—	Configuration for the index breadcrumb. Properties: `id`, `url`, `text`.
`crumbs`	`array`	—	Authored trail links after the index crumb. Each has: `id`, `url`, `text`, `is_current_page`, optional `asIcon`, and optional nested `crumbs` for a dropdown.
`style`	`object`	`{ spacing: { blockGap: { left: "var:preset\|spacing\|50" } } }`	Default horizontal spacing between breadcrumb items.

Supports

Feature	Enabled	Notes
Anchor	Yes
HTML editing	No
Color: background	Yes
Color: text	Yes
Color: link	Yes
Color: heading	Yes
Spacing: blockGap	Yes (horizontal only)	Controls spacing between breadcrumb items
Spacing: margin	Yes (top, bottom only)
Spacing: padding	Yes (default control)
Typography: fontSize	Yes (default control)
Typography: fontFamily	Yes (default control)
Border: color, style, width	Yes (all default controls)
Interactivity	Yes	Dropdown crumbs use `prc-block/breadcrumbs`

Context

Context	Description
`postId`	Current post ID.
`postType`	Current post type.
`query`	Query context.
`queryId`	Query loop ID.
`previewPostType`	Preview post type in the editor.

Usage Instructions

Insert the Breadcrumbs block, typically in a site template header area.
Configure the home crumb text and URL in the sidebar controls.
Optionally configure an index/section crumb (e.g., "Research" linking to a topic index).
Toggle showCurrentPageTitle to include or exclude the current page in the trail.
Choose a separator character (defaults to >).
Adjust content justification (left, center, right) as needed.
Optionally toggle Show home as icon to render a house icon instead of home text.
Add extra Trail links after the index crumb when a project needs a fixed prefix such as Research Topics > Religion > Interactive.
The rest of the trail is generated from the post hierarchy or taxonomy unless a plugin replaces it.

Block Markup Example

<nav
	class="wp-block-prc-block-breadcrumbs is-content-justification-left"
	id="breadcrumbs-abc123"
	aria-label="Breadcrumbs"
	style="--breadcrumbs-gap: 1em;"
>
	<div class="prc-block-breadcrumbs__list">
		<div class="prc-block-breadcrumbs__item">
			<a href="/"><span>Home</span></a>
		</div>
		<span class="prc-block-breadcrumbs__separator" aria-hidden="true"
			>></span
		>
		<div class="prc-block-breadcrumbs__item">
			<a href="/research/"><span>Research</span></a>
		</div>
		<span class="prc-block-breadcrumbs__separator" aria-hidden="true"
			>></span
		>
		<div class="prc-block-breadcrumbs__item">
			<a href="/research/topic/" aria-current="page"
				><span>Current Page</span></a
			>
		</div>
	</div>
</nav>

PHP Rendering

The render_block_callback in class-breadcrumbs.php is fully server-side rendered. It:

Determines the current queried object type (WP_Post, WP_Term, WP_Post_Type, WP_User).
For attachment pages, redirects to the parent post for breadcrumb generation.
For hierarchical post types (pages), walks up the ancestor chain using get_ancestors().
For non-hierarchical post types (posts, reports), uses the primary term in the category taxonomy via \PRC\Platform\get_primary_term_id() and walks up the term hierarchy.
For taxonomy terms, walks up the term ancestor chain.
Constructs the breadcrumb array: home crumb (text or house icon), index crumb, authored crumbs, ancestors, and optionally the current page.
Applies the prc_platform_breadcrumbs filter so other plugins can replace or extend the list. The filter takes one argument. A second argument would break Religious Landscape Study, which uses that slot as a Schema.org flag.
Renders each crumb as a link, a button (dropdown with no URL), or a span. Separators sit between items.
A crumb with a nested crumbs array is a dropdown. The trigger shows a caret. Click the trigger (or press Enter/Space) to toggle the menu. Hover does not open it.

Object cache

Trail assembly (ancestor lookups and taxonomy walks) is cached in the prc_breadcrumbs object cache group with a 1-hour TTL. Caching applies only for logged-out, non-preview requests.

Cache key includes a version token per queried object (post:{id}, term:{id}, etc.).
Home and index crumbs (homeCrumb, indexCrumb block attributes) are merged after the cache lookup and are not part of the cached trail payload.
Invalidation: prc_platform_on_update bumps the version for the updated post; edited_term bumps the version for the edited term and, for category terms, for the primary category used in post trails.

Core Breadcrumbs Disabled

The PHP class filters allowed_block_types_all to remove yoast-seo/breadcrumbs and core/breadcrumbs from the block inserter.

Crumb record

Plugins that hook prc_platform_breadcrumbs should return this shape:

Field	Type	Meaning
`url`	`string`	Destination. Empty or `null` renders a span or a dropdown button.
`text`	`string`	Visible label. HTML is allowed so existing icon markup keeps working.
`asIcon`	`boolean`	When true, the block renders a house icon and uses `text` as the accessible name.
`is_current_page`	`boolean`	Marks the current location (`aria-current="page"`).
`visible`	`boolean`	When false the crumb is skipped in the visible trail (Schema.org use).
`crumbs`	`array`	Nested crumb records. Presence turns this crumb into a dropdown.

Religious Projections replaces the trail on its routes with a home icon, the Research Topics > Religion > Interactive prefix, then a collection dropdown (Religions, Regions, or the parent region) and the current entity.

Frontend Interactivity

Dropdown crumbs use the Interactivity API store prc-block/breadcrumbs. Click the caret or unlabeled trigger to toggle. Escape dismisses the menu. A click outside also closes it. Clicking a submenu link closes the menu before navigation. The list is visible only while the crumb has the is-open class.

Styles

Key CSS behaviors:

The breadcrumb list is a wrapping flex row. Overflow is visible so dropdowns are not clipped.
Items are spaced using the --breadcrumbs-gap CSS custom property.
The current page (a[aria-current="page"]) is displayed in bold.
Sub-lists (.prc-block-breadcrumbs__sub_list) are hidden by default and shown only when the crumb has the is-open class. They are absolute-positioned menus with a white background, box shadow, rounded corners, and a max height for long country lists.

This block is standalone. It is typically used in site-wide templates alongside navigation blocks.