Block Editor: Check for multiple block usage in the block-editor pack…

…age (WordPress#62086)

Co-authored-by: youknowriad <[email protected]>
Co-authored-by: ellatrix <[email protected]>

packages/block-editor/src/components/block-edit/index.js

@@ -1,9 +1,9 @@
 /**
  * WordPress dependencies
  */
-import { useMemo } from '@wordpress/element';
-
+import { useMemo, useContext } from '@wordpress/element';
 import { hasBlockSupport } from '@wordpress/blocks';
+
 /**
  * Internal dependencies
  */
@@ -17,6 +17,8 @@ import {
 	blockBindingsKey,
 	isPreviewModeKey,
 } from './context';
+import { MultipleUsageWarning } from './multiple-usage-warning';
+import { PrivateBlockContext } from '../block-list/private-block-context';
 
 /**
  * The `useBlockEditContext` hook provides information about the block this hook is being used in.
@@ -49,6 +51,8 @@ export default function BlockEdit( {
 	const layoutSupport =
 		hasBlockSupport( name, 'layout', false ) ||
 		hasBlockSupport( name, '__experimentalLayout', false );
+	const { originalBlockClientId } = useContext( PrivateBlockContext );
+
 	return (
 		<BlockEditContextProvider
 			// It is important to return the same object if props haven't
@@ -85,6 +89,13 @@ export default function BlockEdit( {
 			) }
 		>
 			<Edit { ...props } />
+			{ originalBlockClientId && (
+				<MultipleUsageWarning
+					originalBlockClientId={ originalBlockClientId }
+					name={ name }
+					onReplace={ props.onReplace }
+				/>
+			) }
 		</BlockEditContextProvider>
 	);
 }

packages/block-editor/src/components/block-edit/multiple-usage-warning.js

@@ -0,0 +1,46 @@
+/**
+ * WordPress dependencies
+ */
+import { getBlockType } from '@wordpress/blocks';
+import { Button } from '@wordpress/components';
+import { useDispatch } from '@wordpress/data';
+import { __ } from '@wordpress/i18n';
+
+/**
+ * Internal dependencies
+ */
+import { store as blockEditorStore } from '../../store';
+import Warning from '../warning';
+
+export function MultipleUsageWarning( {
+	originalBlockClientId,
+	name,
+	onReplace,
+} ) {
+	const { selectBlock } = useDispatch( blockEditorStore );
+	const blockType = getBlockType( name );
+
+	return (
+		<Warning
+			actions={ [
+				<Button
+					key="find-original"
+					variant="secondary"
+					onClick={ () => selectBlock( originalBlockClientId ) }
+				>
+					{ __( 'Find original' ) }
+				</Button>,
+				<Button
+					key="remove"
+					variant="secondary"
+					onClick={ () => onReplace( [] ) }
+				>
+					{ __( 'Remove' ) }
+				</Button>,
+			] }
+		>
+			<strong>{ blockType?.title }: </strong>
+			{ __( 'This block can only be used once.' ) }
+		</Warning>
+	);
+}

packages/block-editor/src/components/block-list/block.js

@@ -23,6 +23,7 @@ import {
 	isUnmodifiedBlock,
 	isReusableBlock,
 	getBlockDefaultClassName,
+	hasBlockSupport,
 	store as blocksStore,
 } from '@wordpress/blocks';
 import { withFilters } from '@wordpress/components';
@@ -534,6 +535,7 @@ function BlockListBlockProvider( props ) {
 				isFirstMultiSelectedBlock,
 				getMultiSelectedBlockClientIds,
 				hasSelectedInnerBlock,
+				getBlocksByName,
 
 				getBlockIndex,
 				isBlockMultiSelected,
@@ -607,6 +609,17 @@ function BlockListBlockProvider( props ) {
 			const movingClientId = hasBlockMovingClientId();
 			const blockEditingMode = getBlockEditingMode( clientId );
 
+			const multiple = hasBlockSupport( blockName, 'multiple', true );
+
+			// For block types with `multiple` support, there is no "original
+			// block" to be found in the content, as the block itself is valid.
+			const blocksWithSameName = multiple
+				? []
+				: getBlocksByName( blockName );
+			const isInvalid =
+				blocksWithSameName.length &&
+				blocksWithSameName[ 0 ] !== clientId;
+
 			return {
 				...previewContext,
 				mode: getBlockMode( clientId ),
@@ -664,6 +677,9 @@ function BlockListBlockProvider( props ) {
 				hasEditableOutline:
 					blockEditingMode !== 'disabled' &&
 					getBlockEditingMode( rootClientId ) === 'disabled',
+				originalBlockClientId: isInvalid
+					? blocksWithSameName[ 0 ]
+					: false,
 			};
 		},
 		[ clientId, rootClientId ]
@@ -707,6 +723,7 @@ function BlockListBlockProvider( props ) {
 		hasEditableOutline,
 		className,
 		defaultClassName,
+		originalBlockClientId,
 	} = selectedProps;
 
 	// Users of the editor.BlockListBlock filter used to be able to
@@ -754,6 +771,7 @@ function BlockListBlockProvider( props ) {
 		defaultClassName,
 		mayDisplayControls,
 		mayDisplayParentControls,
+		originalBlockClientId,
 		themeSupportsLayout,
 	};
 

packages/edit-post/src/index.js

@@ -19,7 +19,6 @@ import { store as editorStore } from '@wordpress/editor';
 /**
  * Internal dependencies
  */
-import './hooks';
 import Editor from './editor';
 
 /**