Restore block cleanup

packages/blocks/src/api/index.js

@@ -61,6 +61,7 @@ export {
 	getSaveElement,
 	getSaveContent,
 	getBlockProps as __unstableGetBlockProps,
+	__unstableSerializeAndClean,
 } from './serializer';
 
 // Validation is the process of comparing a block source with its output before

packages/blocks/src/api/serializer.js

@@ -9,6 +9,7 @@ import { isEmpty, reduce, isObject, castArray, startsWith } from 'lodash';
 import { Component, cloneElement, renderToString } from '@wordpress/element';
 import { hasFilter, applyFilters } from '@wordpress/hooks';
 import isShallowEqual from '@wordpress/is-shallow-equal';
+import { removep } from '@wordpress/autop';
 
 /**
  * Internal dependencies
@@ -19,7 +20,7 @@ import {
 	getUnregisteredTypeHandlerName,
 	hasBlockSupport,
 } from './registration';
-import { normalizeBlockType } from './utils';
+import { isUnmodifiedDefaultBlock, normalizeBlockType } from './utils';
 import BlockContentProvider from '../block-content-provider';
 
 /**
@@ -349,6 +350,28 @@ export function serializeBlock( block, { isInnerBlocks = false } = {} ) {
 	return getCommentDelimitedContent( blockName, saveAttributes, saveContent );
 }
 
+export function __unstableSerializeAndClean( blocks ) {
+	// A single unmodified default block is assumed to
+	// be equivalent to an empty post.
+	if ( blocks.length === 1 && isUnmodifiedDefaultBlock( blocks[ 0 ] ) ) {
+		blocks = [];
+	}
+
+	let content = serialize( blocks );
+
+	// For compatibility, treat a post consisting of a
+	// single freeform block as legacy content and apply
+	// pre-block-editor removep'd content formatting.
+	if (
+		blocks.length === 1 &&
+		blocks[ 0 ].name === getFreeformContentHandlerName()
+	) {
+		content = removep( content );
+	}
+
+	return content;
+}
+
 /**
  * Takes a block or set of blocks and returns the serialized post content.
  *

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

@@ -8,7 +8,7 @@ import {
 	useEffect,
 } from '@wordpress/element';
 import { useSelect, useDispatch } from '@wordpress/data';
-import { parse, serialize } from '@wordpress/blocks';
+import { parse, __unstableSerializeAndClean } from '@wordpress/blocks';
 
 const EMPTY_ARRAY = [];
 
@@ -183,7 +183,7 @@ export function useEntityBlockEditor( kind, type, { id: _id } = {} ) {
 			// to make sure the edit makes the post dirty and creates
 			// a new undo level.
 			edits.content = ( { blocks: blocksForSerialization = [] } ) =>
-				serialize( blocksForSerialization );
+				__unstableSerializeAndClean( blocksForSerialization );
 
 			editEntityRecord( 'postType', type, id, edits );
 		},

packages/editor/src/store/actions.js

@@ -9,7 +9,11 @@ import { has } from 'lodash';
 import deprecated from '@wordpress/deprecated';
 import { controls } from '@wordpress/data';
 import { apiFetch } from '@wordpress/data-controls';
-import { parse, synchronizeBlocksWithTemplate } from '@wordpress/blocks';
+import {
+	parse,
+	synchronizeBlocksWithTemplate,
+	__unstableSerializeAndClean,
+} from '@wordpress/blocks';
 import { store as noticesStore } from '@wordpress/notices';
 
 /**
@@ -21,7 +25,6 @@ import {
 	getNotificationArgumentsForSaveFail,
 	getNotificationArgumentsForTrashFail,
 } from './utils/notice-builder';
-import serializeBlocks from './utils/serialize-blocks';
 
 /**
  * Returns an action generator used in signalling that editor has initialized with
@@ -624,7 +627,7 @@ export function* resetEditorBlocks( blocks, options = {} ) {
 		// to make sure the edit makes the post dirty and creates
 		// a new undo level.
 		edits.content = ( { blocks: blocksForSerialization = [] } ) =>
-			serializeBlocks( blocksForSerialization );
+			__unstableSerializeAndClean( blocksForSerialization );
 	}
 	yield* editPost( edits );
 }

packages/editor/src/store/selectors.js

@@ -20,6 +20,7 @@ import {
 	getFreeformContentHandlerName,
 	getDefaultBlockName,
 	isUnmodifiedDefaultBlock,
+	__unstableSerializeAndClean,
 } from '@wordpress/blocks';
 import { isInTheFuture, getDate } from '@wordpress/date';
 import { addQueryArgs } from '@wordpress/url';
@@ -38,7 +39,6 @@ import {
 	AUTOSAVE_PROPERTIES,
 } from './constants';
 import { getPostRawValue } from './reducer';
-import serializeBlocks from './utils/serialize-blocks';
 import { cleanForSlug } from '../utils/url';
 
 /**
@@ -991,7 +991,7 @@ export const getEditedPostContent = createRegistrySelector(
 			if ( typeof record.content === 'function' ) {
 				return record.content( record );
 			} else if ( record.blocks ) {
-				return serializeBlocks( record.blocks );
+				return __unstableSerializeAndClean( record.blocks );
 			} else if ( record.content ) {
 				return record.content;
 			}