@wordpress/data/src/resolvers-cache-middleware.js

Data module for WordPress.

/**
 * External dependencies
 */
import { get } from 'lodash';

/**
 * Internal dependencies
 */
import coreDataStore from './store';

/** @typedef {import('./registry').WPDataRegistry} WPDataRegistry */

/**
 * Creates a middleware handling resolvers cache invalidation.
 *
 * @param {WPDataRegistry} registry   The registry reference for which to create
 *                                    the middleware.
 * @param {string}         reducerKey The namespace for which to create the
 *                                    middleware.
 *
 * @return {Function} Middleware function.
 */
const createResolversCacheMiddleware =
	( registry, reducerKey ) => () => ( next ) => ( action ) => {
		const resolvers = registry
			.select( coreDataStore )
			.getCachedResolvers( reducerKey );
		Object.entries( resolvers ).forEach(
			( [ selectorName, resolversByArgs ] ) => {
				const resolver = get( registry.stores, [
					reducerKey,
					'resolvers',
					selectorName,
				] );
				if ( ! resolver || ! resolver.shouldInvalidate ) {
					return;
				}
				resolversByArgs.forEach( ( value, args ) => {
					// resolversByArgs is the map Map([ args ] => boolean) storing the cache resolution status for a given selector.
					// If the value is "finished" or "error" it means this resolver has finished its resolution which means we need
					// to invalidate it, if it's true it means it's inflight and the invalidation is not necessary.
					if (
						( value?.status !== 'finished' &&
							value?.status !== 'error' ) ||
						! resolver.shouldInvalidate( action, ...args )
					) {
						return;
					}

					// Trigger cache invalidation
					registry
						.dispatch( coreDataStore )
						.invalidateResolution( reducerKey, selectorName, args );
				} );
			}
		);
		return next( action );
	};

export default createResolversCacheMiddleware;