initial commit

packages/woocommerce-blocks/assets/js/data/collections/selectors.js

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+/**
+ * External dependencies
+ */
+import { addQueryArgs } from '@wordpress/url';
+
+/**
+ * Internal dependencies
+ */
+import { hasInState } from '../utils';
+import { DEFAULT_EMPTY_ARRAY } from './constants';
+
+const getFromState = ( {
+	state,
+	namespace,
+	resourceName,
+	query,
+	ids,
+	type = 'items',
+	fallback = DEFAULT_EMPTY_ARRAY,
+} ) => {
+	// prep ids and query for state retrieval
+	ids = JSON.stringify( ids );
+	query = query !== null ? addQueryArgs( '', query ) : '';
+	if ( hasInState( state, [ namespace, resourceName, ids, query, type ] ) ) {
+		return state[ namespace ][ resourceName ][ ids ][ query ][ type ];
+	}
+	return fallback;
+};
+
+const getCollectionHeaders = (
+	state,
+	namespace,
+	resourceName,
+	query = null,
+	ids = DEFAULT_EMPTY_ARRAY
+) => {
+	return getFromState( {
+		state,
+		namespace,
+		resourceName,
+		query,
+		ids,
+		type: 'headers',
+		fallback: undefined,
+	} );
+};
+
+/**
+ * Retrieves the collection items from the state for the given arguments.
+ *
+ * @param {Object} state        The current collections state.
+ * @param {string} namespace    The namespace for the collection.
+ * @param {string} resourceName The resource name for the collection.
+ * @param {Object} [query=null] The query for the collection request.
+ * @param {Array}  [ids=[]]     Any ids for the collection request (these are
+ *                              values that would be added to the route for a
+ *                              route with id placeholders)
+ * @return {Array} an array of items stored in the collection.
+ */
+export const getCollection = (
+	state,
+	namespace,
+	resourceName,
+	query = null,
+	ids = DEFAULT_EMPTY_ARRAY
+) => {
+	return getFromState( { state, namespace, resourceName, query, ids } );
+};
+
+export const getCollectionError = (
+	state,
+	namespace,
+	resourceName,
+	query = null,
+	ids = DEFAULT_EMPTY_ARRAY
+) => {
+	return getFromState( {
+		state,
+		namespace,
+		resourceName,
+		query,
+		ids,
+		type: 'error',
+		fallback: null,
+	} );
+};
+
+/**
+ * This selector enables retrieving a specific header value from a given
+ * collection request.
+ *
+ * Example:
+ *
+ * ```js
+ * const totalProducts = wp.data.select( COLLECTION_STORE_KEY )
+ *   .getCollectionHeader( '/wc/blocks', 'products', 'x-wp-total' )
+ * ```
+ *
+ * @param {string} state        The current collection state.
+ * @param {string} header       The header to retrieve.
+ * @param {string} namespace    The namespace for the collection.
+ * @param {string} resourceName The model name for the collection.
+ * @param {Object} [query=null] The query object on the collection request.
+ * @param {Array}  [ids=[]]     Any ids for the collection request (these are
+ *                              values that would be added to the route for a
+ *                              route with id placeholders)
+ *
+ * @return {*|null} The value for the specified header, null if there are no
+ * headers available and undefined if the header does not exist for the
+ * collection.
+ */
+export const getCollectionHeader = (
+	state,
+	header,
+	namespace,
+	resourceName,
+	query = null,
+	ids = DEFAULT_EMPTY_ARRAY
+) => {
+	const headers = getCollectionHeaders(
+		state,
+		namespace,
+		resourceName,
+		query,
+		ids
+	);
+	// Can't just do a truthy check because `getCollectionHeaders` resolver
+	// invokes the `getCollection` selector to trigger the resolution of the
+	// collection request. Its fallback is an empty array.
+	if ( headers && headers.get ) {
+		return headers.has( header ) ? headers.get( header ) : undefined;
+	}
+	return null;
+};
+
+/**
+ * Gets the last modified header for the collection.
+ *
+ * @param {string} state The current collection state.
+ * @return {number} Timestamp.
+ */
+export const getCollectionLastModified = ( state ) => {
+	return state.lastModified || 0;
+};