From 0a88191394a7f5710338ce73c94ddae831607918 Mon Sep 17 00:00:00 2001
From: brandonkelly <brandon@pixelandtonic.com>
Date: Wed, 15 May 2019 07:06:05 -0700
Subject: [PATCH] Reset Matrix & relation field values after saving a new
 element

---
 CHANGELOG-v3.md                  | 1 +
 src/fields/BaseRelationField.php | 5 +++++
 src/services/Matrix.php          | 5 +++++
 3 files changed, 11 insertions(+)

diff --git a/CHANGELOG-v3.md b/CHANGELOG-v3.md
index 524c22160d3..dbce897468e 100644
--- a/CHANGELOG-v3.md
+++ b/CHANGELOG-v3.md
@@ -5,6 +5,7 @@
 ### Fixed
 - Fixed a bug where slugs could get double-hyphenated. ([#4266](https://github.com/craftcms/cms/issues/4266))
 - Fixed an error that would occur when installing Craft if the `allowAdminChanges` config setting was disabled. ([#4267](https://github.com/craftcms/cms/issues/4267))
+- Fixed a bug where Matrix fields would return the wrong set of Matrix blocks on new or duplicated elements, immediately after they were saved.
 
 ## 3.1.27 - 2019-05-14
 
diff --git a/src/fields/BaseRelationField.php b/src/fields/BaseRelationField.php
index 1731794fe86..421abd8de1d 100644
--- a/src/fields/BaseRelationField.php
+++ b/src/fields/BaseRelationField.php
@@ -543,6 +543,11 @@ public function afterElementSave(ElementInterface $element, bool $isNew)
 
             /** @var int|int[]|false|null $targetIds */
             Craft::$app->getRelations()->saveRelations($this, $element, $targetIds);
+
+            // Reset the field value if this is a new element
+            if ($isNew) {
+                $element->setFieldValue($this->handle, null);
+            }
         }
 
         parent::afterElementSave($element, $isNew);
diff --git a/src/services/Matrix.php b/src/services/Matrix.php
index 514e0d5c67c..4a84f82d5ee 100644
--- a/src/services/Matrix.php
+++ b/src/services/Matrix.php
@@ -814,6 +814,11 @@ public function saveField(MatrixField $field, ElementInterface $owner)
             throw $e;
         }
 
+        // Reset the field value if this is a new element
+        if ($owner->duplicateOf || !$query->ownerId) {
+            $owner->setFieldValue($field->handle, null);
+        }
+
         // Tell the browser to collapse any new block IDs
         if (!Craft::$app->getRequest()->getIsConsoleRequest() && !Craft::$app->getResponse()->isSent && !empty($collapsedBlockIds)) {
             Craft::$app->getSession()->addAssetBundleFlash(MatrixAsset::class);