Editor: Implement EntityProvider and use it to refactor custom sources with a backwards compatibility hook for meta sources.

packages/core-data/package.json

@@ -26,6 +26,7 @@
 		"@wordpress/api-fetch": "file:../api-fetch",
 		"@wordpress/data": "file:../data",
 		"@wordpress/deprecated": "file:../deprecated",
+		"@wordpress/element": "file:../element",
 		"@wordpress/is-shallow-equal": "file:../is-shallow-equal",
 		"@wordpress/url": "file:../url",
 		"equivalent-key-map": "^0.2.2",

packages/core-data/src/entity-provider.js

@@ -0,0 +1,90 @@
+/**
+ * WordPress dependencies
+ */
+import { createContext, useContext, useCallback } from '@wordpress/element';
+import { useSelect, useDispatch } from '@wordpress/data';
+
+/**
+ * Internal dependencies
+ */
+import { defaultEntities, kinds } from './entities';
+
+const entities = {
+	...defaultEntities.reduce( ( acc, entity ) => {
+		if ( ! acc[ entity.kind ] ) {
+			acc[ entity.kind ] = {};
+		}
+		acc[ entity.kind ][ entity.name ] = { context: createContext() };
+		return acc;
+	}, {} ),
+	...kinds.reduce( ( acc, kind ) => {
+		acc[ kind.name ] = {};
+		return acc;
+	}, {} ),
+};
+const getEntity = ( kind, type ) => {
+	if ( ! entities[ kind ] ) {
+		throw new Error( `Missing entity config for kind: ${ kind }.` );
+	}
+
+	if ( ! entities[ kind ][ type ] ) {
+		entities[ kind ][ type ] = { context: createContext() };
+	}
+
+	return entities[ kind ][ type ];
+};
+
+/**
+ * Context provider component for providing
+ * an entity for a specific entity type.
+ *
+ * @param {Object} props          The component's props.
+ * @param {string} props.kind     The entity kind.
+ * @param {string} props.type     The entity type.
+ * @param {number} props.id       The entity ID.
+ * @param {*}      props.children The children to wrap.
+ *
+ * @return {Object} The provided children, wrapped with
+ *                   the entity's context provider.
+ */
+export default function EntityProvider( { kind, type, id, children } ) {
+	const Provider = getEntity( kind, type ).context.Provider;
+	return <Provider value={ id }>{ children }</Provider>;
+}
+
+/**
+ * Hook that returns the value and a setter for the
+ * specified property of the nearest provided
+ * entity of the specified type.
+ *
+ * @param {string} kind The entity kind.
+ * @param {string} type The entity type.
+ * @param {string} prop The property name.
+ *
+ * @return {[*, Function]} A tuple where the first item is the
+ *                          property value and the second is the
+ *                          setter.
+ */
+export function useEntityProp( kind, type, prop ) {
+	const id = useContext( getEntity( kind, type ).context );
+
+	const value = useSelect(
+		( select ) => {
+			const entity = select( 'core' ).getEditedEntityRecord( kind, type, id );
+			return entity && entity[ prop ];
+		},
+		[ kind, type, id, prop ]
+	);
+
+	const { editEntityRecord } = useDispatch( 'core' );
+	const setValue = useCallback(
+		( newValue ) => {
+			editEntityRecord( kind, type, id, {
+				[ prop ]: newValue,
+			} );
+		},
+		[ kind, type, id, prop ]
+	);
+
+	return [ value, setValue ];
+}

packages/core-data/src/index.js

@@ -48,3 +48,5 @@ registerStore( REDUCER_KEY, {
 	selectors: { ...selectors, ...entitySelectors },
 	resolvers: { ...resolvers, ...entityResolvers },
 } );
+
+export { default as EntityProvider, useEntityProp } from './entity-provider';

packages/editor/src/components/provider/index.js

@@ -11,6 +11,7 @@ import { compose } from '@wordpress/compose';
 import { Component } from '@wordpress/element';
 import { withDispatch, withSelect } from '@wordpress/data';
 import { __ } from '@wordpress/i18n';
+import { EntityProvider } from '@wordpress/core-data';
 import { BlockEditorProvider, transformStyles } from '@wordpress/block-editor';
 import apiFetch from '@wordpress/api-fetch';
 import { addQueryArgs } from '@wordpress/url';
@@ -164,6 +165,7 @@ class EditorProvider extends Component {
 		const {
 			canUserUseUnfilteredHTML,
 			children,
+			post,
 			blocks,
 			resetEditorBlocks,
 			isReady,
@@ -185,18 +187,20 @@ class EditorProvider extends Component {
 		);
 
 		return (
-			<BlockEditorProvider
-				value={ blocks }
-				onInput={ resetEditorBlocksWithoutUndoLevel }
-				onChange={ resetEditorBlocks }
-				settings={ editorSettings }
-				useSubRegistry={ false }
-			>
-				{ children }
-				<ReusableBlocksButtons />
-				<ConvertToGroupButtons />
-				{ editorSettings.__experimentalBlockDirectory && <InserterMenuDownloadableBlocksPanel /> }
-			</BlockEditorProvider>
+			<EntityProvider kind="postType" type={ post.type } id={ post.id }>
+				<BlockEditorProvider
+					value={ blocks }
+					onInput={ resetEditorBlocksWithoutUndoLevel }
+					onChange={ resetEditorBlocks }
+					settings={ editorSettings }
+					useSubRegistry={ false }
+				>
+					{ children }
+					<ReusableBlocksButtons />
+					<ConvertToGroupButtons />
+					{ editorSettings.__experimentalBlockDirectory && <InserterMenuDownloadableBlocksPanel /> }
+				</BlockEditorProvider>
+			</EntityProvider>
 		);
 	}
 }

packages/editor/src/hooks/custom-sources-backwards-compatibility.js

@@ -0,0 +1,73 @@
+/**
+ * WordPress dependencies
+ */
+import { getBlockType } from '@wordpress/blocks';
+import { useEntityProp } from '@wordpress/core-data';
+import { useMemo, useCallback } from '@wordpress/element';
+import { createHigherOrderComponent } from '@wordpress/compose';
+import { addFilter } from '@wordpress/hooks';
+
+const EMPTY_OBJECT = {};
+function useMetaAttributeSource( name, _attributes, _setAttributes ) {
+	const { attributes: attributeTypes = EMPTY_OBJECT } =
+		getBlockType( name ) || EMPTY_OBJECT;
+	let [ attributes, setAttributes ] = [ _attributes, _setAttributes ];
+
+	if ( Object.values( attributeTypes ).some( ( type ) => type.source === 'meta' ) ) {
+		// eslint-disable-next-line react-hooks/rules-of-hooks
+		const [ meta, setMeta ] = useEntityProp( 'postType', 'post', 'meta' );
+
+		// eslint-disable-next-line react-hooks/rules-of-hooks
+		attributes = useMemo(
+			() => ( {
+				..._attributes,
+				...Object.keys( attributeTypes ).reduce( ( acc, key ) => {
+					if ( attributeTypes[ key ].source === 'meta' ) {
+						acc[ key ] = meta[ attributeTypes[ key ].meta ];
+					}
+					return acc;
+				}, {} ),
+			} ),
+			[ attributeTypes, meta, _attributes ]
+		);
+
+		// eslint-disable-next-line react-hooks/rules-of-hooks
+		setAttributes = useCallback(
+			( ...args ) => {
+				Object.keys( args[ 0 ] ).forEach( ( key ) => {
+					if ( attributeTypes[ key ].source === 'meta' ) {
+						setMeta( { [ attributeTypes[ key ].meta ]: args[ 0 ][ key ] } );
+					}
+				} );
+				return _setAttributes( ...args );
+			},
+			[ attributeTypes, setMeta, _setAttributes ]
+		);
+	}
+
+	return [ attributes, setAttributes ];
+}
+const withMetaAttributeSource = createHigherOrderComponent(
+	( BlockListBlock ) => ( { attributes, setAttributes, name, ...props } ) => {
+		[ attributes, setAttributes ] = useMetaAttributeSource(
+			name,
+			attributes,
+			setAttributes
+		);
+		return (
+			<BlockListBlock
+				attributes={ attributes }
+				setAttributes={ setAttributes }
+				name={ name }
+				{ ...props }
+			/>
+		);
+	},
+	'withMetaAttributeSource'
+);
+
+addFilter(
+	'editor.BlockListBlock',
+	'core/editor/custom-sources-backwards-compatibility/with-meta-attribute-source',
+	withMetaAttributeSource
+);

packages/editor/src/hooks/index.js

@@ -1,4 +1,5 @@
 /**
  * Internal dependencies
  */
+import './custom-sources-backwards-compatibility';
 import './default-autocompleters';