Core Data: Add getPostMedia

core-data/resolvers.js

@@ -35,6 +35,17 @@ export async function* getMedia( state, id ) {
 	yield receiveMedia( media );
 }
 
+/**
+ * Requests all media elements attached to a post from the REST API.
+ *
+ * @param {Object} state  State tree.
+ * @param {number} postId Post id.
+ */
+export async function* getPostMedia( state, postId ) {
+	const media = await apiRequest( { path: `/wp/v2/media?parent=${ postId }` } );
+	yield receiveMedia( media );
+}
+
 /**
  * Requests a post type element from the REST API.
  *

core-data/selectors.js

@@ -1,3 +1,8 @@
+/**
+ * External dependencies
+ */
+import { filter } from 'lodash';
+
 /**
  * Returns all the available terms for the given taxonomy.
  *
@@ -58,6 +63,18 @@ export function getMedia( state, id ) {
 	return state.media[ id ];
 }
 
+/**
+ * Returns media objects attached to a post, given a post ID.
+ *
+ * @param {Object} state  Data state.
+ * @param {number} postId Post id.
+ *
+ * @return {Array} Media list.
+ */
+export function getPostMedia( state, postId ) {
+	return filter( state.media, { post: postId } );
+}
+
 /**
  * Returns the Post Type object by slug.
  *

core-data/test/resolvers.js

@@ -6,7 +6,7 @@ import apiRequest from '@wordpress/api-request';
 /**
  * Internal dependencies
  */
-import { getCategories, getMedia, getPostType } from '../resolvers';
+import { getCategories, getMedia, getPostMedia, getPostType } from '../resolvers';
 import { setRequested, receiveTerms, receiveMedia, receivePostTypes } from '../actions';
 
 jest.mock( '@wordpress/api-request' );
@@ -49,6 +49,24 @@ describe( 'getMedia', () => {
 	} );
 } );
 
+describe( 'getPostMedia', () => {
+	const MEDIA = [ { id: 10 }, { id: 20 } ];
+
+	beforeAll( () => {
+		apiRequest.mockImplementation( ( options ) => {
+			if ( options.path === '/wp/v2/media?parent=1' ) {
+				return Promise.resolve( MEDIA );
+			}
+		} );
+	} );
+
+	it( 'yields with requested media', async () => {
+		const fulfillment = getPostMedia( {}, 1 );
+		const received = ( await fulfillment.next() ).value;
+		expect( received ).toEqual( receiveMedia( MEDIA ) );
+	} );
+} );
+
 describe( 'getPostType', () => {
 	const POST_TYPE = { slug: 'post' };
 

core-data/test/selectors.js

@@ -6,7 +6,7 @@ import deepFreeze from 'deep-freeze';
 /**
  * Internal dependencies
  */
-import { getTerms, isRequestingTerms, getMedia, getPostType } from '../selectors';
+import { getTerms, isRequestingTerms, getMedia, getPostMedia, getPostType } from '../selectors';
 
 describe( 'getTerms()', () => {
 	it( 'returns value of terms by taxonomy', () => {
@@ -75,6 +75,30 @@ describe( 'getMedia', () => {
 	} );
 } );
 
+describe( 'getPostMedia', () => {
+	it( 'should return undefined for unknown media', () => {
+		const state = deepFreeze( {
+			media: {},
+		} );
+		expect( getPostMedia( state, 1 ) ).toEqual( [] );
+	} );
+
+	it( 'should return a media element by id', () => {
+		const state = deepFreeze( {
+			media: {
+				1: { id: 1, post: 42 },
+				2: { id: 2, post: 42 },
+				3: { id: 3, post: 84 },
+				4: { id: 4 },
+			},
+		} );
+		expect( getPostMedia( state, 42 ) ).toEqual( [
+			{ id: 1, post: 42 },
+			{ id: 2, post: 42 },
+		] );
+	} );
+} );
+
 describe( 'getPostType', () => {
 	it( 'should return undefined for unknown post type', () => {
 		const state = deepFreeze( {