Limit of Next Page (Page Break) block to root level only (#18260)

* WIP - playing around with options to allow limiting of nextpage block to root level only

* Changes from code review

* Update todo comment

* Add unit test

* Update packages/block-editor/src/store/selectors.js

Co-Authored-By: Enrique Piqueras <epiqueras@users.noreply.github.com>

* Fix linting issue

Co-Authored-By: Enrique Piqueras <epiqueras@users.noreply.github.com>

* Fix linting issue

Co-Authored-By: Enrique Piqueras <epiqueras@users.noreply.github.com>

* Fix linting issue

Co-Authored-By: Enrique Piqueras <epiqueras@users.noreply.github.com>

* Changes from review

packages/block-editor/src/store/selectors.js

@@ -1048,6 +1048,12 @@ const canInsertBlockTypeUnmemoized = ( state, blockName, rootClientId = null ) =
  return list;
  }
  if ( isArray( list ) ) {
+ // TODO: when there is a canonical way to detect that we are editing a post
+ // the following check should be changed to something like:
+ // if ( includes( list, 'core/post-content' ) && getEditorMode() === 'post-content' && item === null )
+ if ( includes( list, 'core/post-content' ) && item === null ) {
+ return true;
+ }
  return includes( list, item );
  }
  return defaultResult;

packages/block-editor/src/store/test/selectors.js

@@ -121,6 +121,15 @@ describe( 'selectors', () => {
  },
  } );
 
+ registerBlockType( 'core/post-content-child', {
+ save: () => null,
+ category: 'common',
+ title: 'Test Block Post Content Child',
+ icon: 'test',
+ keywords: [ 'testing' ],
+ parent: [ 'core/post-content' ],
+ } );
+
  setFreeformContentHandlerName( 'core/test-freeform' );
 
  cachedSelectors.forEach( ( { clear } ) => clear() );
@@ -132,6 +141,7 @@ describe( 'selectors', () => {
  unregisterBlockType( 'core/test-block-b' );
  unregisterBlockType( 'core/test-block-c' );
  unregisterBlockType( 'core/test-freeform' );
+ unregisterBlockType( 'core/post-content-child' );
 
  setFreeformContentHandlerName( undefined );
  } );
@@ -1933,6 +1943,34 @@ describe( 'selectors', () => {
  };
  expect( canInsertBlockType( state, 'core/test-block-c', 'block1' ) ).toBe( true );
  } );
+
+ it( 'should deny blocks that restrict parent to core/post-content when not in editor root', () => {
+ const state = {
+ blocks: {
+ byClientId: {
+ block1: { name: 'core/test-block-c' },
+ },
+ attributes: {
+ block1: {},
+ },
+ },
+ blockListSettings: {},
+ settings: {},
+ };
+ expect( canInsertBlockType( state, 'core/post-content-child', 'block1' ) ).toBe( false );
+ } );
+
+ it( 'should allow blocks that restrict parent to core/post-content when in editor root', () => {
+ const state = {
+ blocks: {
+ byClientId: {},
+ attributes: {},
+ },
+ blockListSettings: {},
+ settings: {},
+ };
+ expect( canInsertBlockType( state, 'core/post-content-child' ) ).toBe( true );
+ } );
  } );
 
  describe( 'getInserterItems', () => {
@@ -2033,6 +2071,7 @@ describe( 'selectors', () => {
  };
  const itemIDs = getInserterItems( state ).map( ( item ) => item.id );
  expect( itemIDs ).toEqual( [
+ 'core/post-content-child',
  'core/block/2',
  'core/block/1',
  'core/test-block-b',

packages/block-library/src/nextpage/index.js

@@ -18,6 +18,7 @@ export { metadata, name };
 
 export const settings = {
  title: __( 'Page Break' ),
+ parent: [ 'core/post-content' ],
  description: __( 'Separate your content into a multi-page experience.' ),
  icon,
  keywords: [ __( 'next page' ), __( 'pagination' ) ],