From c80417a949c7f2821ab4ce1f76ccbc5b6649fcaf Mon Sep 17 00:00:00 2001
From: Sam Minnee <sam@silverstripe.com>
Date: Wed, 26 Oct 2016 14:37:58 +1300
Subject: [PATCH] FIX: Fix ViewableData::__isset() for getXXX() getters.

PHP7 is stricter about this.
---
 View/ViewableData.php | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/View/ViewableData.php b/View/ViewableData.php
index 48c542fd4..07af74020 100644
--- a/View/ViewableData.php
+++ b/View/ViewableData.php
@@ -81,12 +81,25 @@ class ViewableData extends Object implements IteratorAggregate {
 
 	/**
 	 * Check if a field exists on this object or its failover.
+	 * Note that, unlike the core isset() implementation, this will return true if the property is defined
+	 * and set to null.
 	 *
 	 * @param string $property
 	 * @return bool
 	 */
 	public function __isset($property) {
-		return $this->hasField($property) || ($this->failover && $this->failover->hasField($property));
+		// getField() isn't a field-specific getter and shouldn't be treated as such
+		if(strtolower($property) !== 'field' && $this->hasMethod($method = "get$property")) {
+			return true;
+
+		} elseif($this->hasField($property)) {
+			return true;
+
+		} elseif($this->failover) {
+			return isset($this->failover->$property);
+		}
+
+		return false;
 	}
 
 	/**
@@ -97,13 +110,17 @@ class ViewableData extends Object implements IteratorAggregate {
 	 * @return mixed
 	 */
 	public function __get($property) {
-		if($this->hasMethod($method = "get$property")) {
+		// getField() isn't a field-specific getter and shouldn't be treated as such
+		if(strtolower($property) !== 'field' && $this->hasMethod($method = "get$property")) {
 			return $this->$method();
+
 		} elseif($this->hasField($property)) {
 			return $this->getField($property);
+
 		} elseif($this->failover) {
 			return $this->failover->$property;
 		}
+
 		return null;
 	}