From 9529670b7c66f954200a85ee13386f678c526f6f Mon Sep 17 00:00:00 2001
From: Jorge Costa <jorge.costa@automattic.com>
Date: Thu, 31 Oct 2019 17:16:15 +0000
Subject: [PATCH] Fix: consecutive updates may trigger a blocks reset (#18219)

---
 .../block-editor/src/components/provider/index.js   | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/packages/block-editor/src/components/provider/index.js b/packages/block-editor/src/components/provider/index.js
index c2b29f13fa74ac..2f49a5d7e77d57 100644
--- a/packages/block-editor/src/components/provider/index.js
+++ b/packages/block-editor/src/components/provider/index.js
@@ -1,7 +1,7 @@
 /**
  * External dependencies
  */
-import { noop } from 'lodash';
+import { last, noop } from 'lodash';
 
 /**
  * WordPress dependencies
@@ -20,6 +20,7 @@ class BlockEditorProvider extends Component {
 		this.props.updateSettings( this.props.settings );
 		this.props.resetBlocks( this.props.value );
 		this.attachChangeObserver( this.props.registry );
+		this.isSyncingOutcomingValue = [];
 	}
 
 	componentDidUpdate( prevProps ) {
@@ -39,20 +40,22 @@ class BlockEditorProvider extends Component {
 			this.attachChangeObserver( registry );
 		}
 
-		if ( this.isSyncingOutcomingValue !== null && this.isSyncingOutcomingValue === value ) {
+		if ( this.isSyncingOutcomingValue.includes( value ) ) {
 			// Skip block reset if the value matches expected outbound sync
 			// triggered by this component by a preceding change detection.
 			// Only skip if the value matches expectation, since a reset should
 			// still occur if the value is modified (not equal by reference),
 			// to allow that the consumer may apply modifications to reflect
 			// back on the editor.
-			this.isSyncingOutcomingValue = null;
+			if ( last( this.isSyncingOutcomingValue ) === value ) {
+				this.isSyncingOutcomingValue = [];
+			}
 		} else if ( value !== prevProps.value ) {
 			// Reset changing value in all other cases than the sync described
 			// above. Since this can be reached in an update following an out-
 			// bound sync, unset the outbound value to avoid considering it in
 			// subsequent renders.
-			this.isSyncingOutcomingValue = null;
+			this.isSyncingOutcomingValue = [];
 			this.isSyncingIncomingValue = value;
 			resetBlocks( value );
 		}
@@ -119,7 +122,7 @@ class BlockEditorProvider extends Component {
 				// When knowing the blocks value is changing, assign instance
 				// value to skip reset in subsequent `componentDidUpdate`.
 				if ( newBlocks !== blocks ) {
-					this.isSyncingOutcomingValue = newBlocks;
+					this.isSyncingOutcomingValue.push( newBlocks );
 				}
 
 				blocks = newBlocks;