From 6ae6285600fee4c184a8f3adc7de87f4ca852a52 Mon Sep 17 00:00:00 2001
From: William Earnhardt <wearnhardt@gmail.com>
Date: Mon, 19 Nov 2018 08:58:50 -0500
Subject: [PATCH] Recursively step through edits to track individually changed
 post meta (#10827)

* Only send edited meta values as state to editPost

* Recursively step through edits to granularly update state on EDIT_POST

* Don't recurse for arrays

* Editor: Deeply diff/merge edited property edits/updates

* Editor: Pass meta updates from block as patch

* Editor: Shallow merge on whitelisted post property edits
---
 .../editor/src/components/block-list/block.js |  7 +-
 packages/editor/src/store/reducer.js          | 21 ++++-
 packages/editor/src/store/test/reducer.js     | 84 +++++++++++++++++++
 3 files changed, 104 insertions(+), 8 deletions(-)

diff --git a/packages/editor/src/components/block-list/block.js b/packages/editor/src/components/block-list/block.js
index 614fbe9f762f0..1263bbe9e40bc 100644
--- a/packages/editor/src/components/block-list/block.js
+++ b/packages/editor/src/components/block-list/block.js
@@ -179,10 +179,7 @@ export class BlockListBlock extends Component {
 		}, {} );
 
 		if ( size( metaAttributes ) ) {
-			this.props.onMetaChange( {
-				...this.props.meta,
-				...metaAttributes,
-			} );
+			this.props.onMetaChange( metaAttributes );
 		}
 	}
 
@@ -646,7 +643,6 @@ const applyWithSelect = withSelect( ( select, { clientId, rootClientId, isLargeV
 		isTyping,
 		isCaretWithinFormattedText,
 		getBlockIndex,
-		getEditedPostAttribute,
 		getBlockMode,
 		isSelectionEnabled,
 		getSelectedBlocksInitialCaretPosition,
@@ -673,7 +669,6 @@ const applyWithSelect = withSelect( ( select, { clientId, rootClientId, isLargeV
 		isTypingWithinBlock: ( isSelected || isParentOfSelectedBlock ) && isTyping(),
 		isCaretWithinFormattedText: isCaretWithinFormattedText(),
 		order: getBlockIndex( clientId, rootClientId ),
-		meta: getEditedPostAttribute( 'meta' ),
 		mode: getBlockMode( clientId ),
 		isSelectionEnabled: isSelectionEnabled(),
 		initialPosition: getSelectedBlocksInitialCaretPosition(),
diff --git a/packages/editor/src/store/reducer.js b/packages/editor/src/store/reducer.js
index 6bfb468cd7157..5396186a9be44 100644
--- a/packages/editor/src/store/reducer.js
+++ b/packages/editor/src/store/reducer.js
@@ -35,6 +35,16 @@ import {
 } from './defaults';
 import { insertAt, moveTo } from './array';
 
+/**
+ * Set of post properties for which edits should assume a merging behavior,
+ * assuming an object value.
+ *
+ * @type {Set}
+ */
+const EDIT_MERGE_PROPERTIES = new Set( [
+	'meta',
+] );
+
 /**
  * Returns a post attribute value, flattening nested rendered content using its
  * raw value in place of its original object form.
@@ -244,7 +254,14 @@ export const editor = flow( [
 					// Only assign into result if not already same value
 					if ( value !== state[ key ] ) {
 						result = getMutateSafeObject( state, result );
-						result[ key ] = value;
+
+						if ( EDIT_MERGE_PROPERTIES.has( key ) ) {
+							// Merge properties should assign to current value.
+							result[ key ] = { ...result[ key ], ...value };
+						} else {
+							// Otherwise override.
+							result[ key ] = value;
+						}
 					}
 
 					return result;
@@ -264,7 +281,7 @@ export const editor = flow( [
 					( key ) => getPostRawValue( action.post[ key ] );
 
 				return reduce( state, ( result, value, key ) => {
-					if ( value !== getCanonicalValue( key ) ) {
+					if ( ! isEqual( value, getCanonicalValue( key ) ) ) {
 						return result;
 					}
 
diff --git a/packages/editor/src/store/test/reducer.js b/packages/editor/src/store/test/reducer.js
index d40b07b0b36bd..e088a2a67012a 100644
--- a/packages/editor/src/store/test/reducer.js
+++ b/packages/editor/src/store/test/reducer.js
@@ -1040,6 +1040,90 @@ describe( 'state', () => {
 				} );
 			} );
 
+			it( 'should merge object values', () => {
+				const original = editor( undefined, {
+					type: 'EDIT_POST',
+					edits: {
+						meta: {
+							a: 1,
+						},
+					},
+				} );
+
+				const state = editor( original, {
+					type: 'EDIT_POST',
+					edits: {
+						meta: {
+							b: 2,
+						},
+					},
+				} );
+
+				expect( state.present.edits ).toEqual( {
+					meta: {
+						a: 1,
+						b: 2,
+					},
+				} );
+			} );
+
+			it( 'return state by reference on unchanging update', () => {
+				const original = editor( undefined, {} );
+
+				const state = editor( original, {
+					type: 'UPDATE_POST',
+					edits: {},
+				} );
+
+				expect( state.present.edits ).toBe( original.present.edits );
+			} );
+
+			it( 'unset reset post values which match by canonical value', () => {
+				const original = editor( undefined, {
+					type: 'EDIT_POST',
+					edits: {
+						title: 'modified title',
+					},
+				} );
+
+				const state = editor( original, {
+					type: 'RESET_POST',
+					post: {
+						title: {
+							raw: 'modified title',
+						},
+					},
+				} );
+
+				expect( state.present.edits ).toEqual( {} );
+			} );
+
+			it( 'unset reset post values by deep match', () => {
+				const original = editor( undefined, {
+					type: 'EDIT_POST',
+					edits: {
+						title: 'modified title',
+						meta: {
+							a: 1,
+							b: 2,
+						},
+					},
+				} );
+
+				const state = editor( original, {
+					type: 'UPDATE_POST',
+					edits: {
+						title: 'modified title',
+						meta: {
+							a: 1,
+							b: 2,
+						},
+					},
+				} );
+
+				expect( state.present.edits ).toEqual( {} );
+			} );
+
 			it( 'should omit content when resetting', () => {
 				// Use case: When editing in Text mode, we defer to content on
 				// the property, but we reset blocks by parse when switching