From 67fdc9e9a7e2e1970006363f0ac73a6360ebe9d6 Mon Sep 17 00:00:00 2001
From: Bob den Otter <bob@twokings.nl>
Date: Tue, 23 Jun 2020 15:29:13 +0200
Subject: [PATCH 1/2] Ensure `$this->fields` is initialised (For Fields that
 haven't been accessed before)

---
 src/Entity/ListFieldTrait.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Entity/ListFieldTrait.php b/src/Entity/ListFieldTrait.php
index 04d90fca5..48fbac12e 100644
--- a/src/Entity/ListFieldTrait.php
+++ b/src/Entity/ListFieldTrait.php
@@ -42,6 +42,9 @@ public function valid(): bool
 
     public function rewind(): void
     {
+        // Ensure $this->fields is initialised
+        $this->fields = $this->getValue();
+
         $this->iteratorCursor = 0;
     }
 }

From 66fef6e365cff967439afa5391791aaf58bc07fc Mon Sep 17 00:00:00 2001
From: Bob den Otter <bob@twokings.nl>
Date: Tue, 23 Jun 2020 15:32:59 +0200
Subject: [PATCH 2/2] Update ListFieldTrait.php

---
 src/Entity/ListFieldTrait.php | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/Entity/ListFieldTrait.php b/src/Entity/ListFieldTrait.php
index 48fbac12e..9c85c989c 100644
--- a/src/Entity/ListFieldTrait.php
+++ b/src/Entity/ListFieldTrait.php
@@ -20,6 +20,15 @@ public function count(): int
         return count($this->getValue());
     }
 
+    /**
+     * Makes ListFieldInterface fields .length attribute
+     * return the number of elements in the field
+     */
+    public function length(): int
+    {
+        return $this->count();
+    }
+
     public function current(): Field
     {
         return $this->fields[$this->iteratorCursor];