From d69520bd70746dce66a0d289cf72464046c165eb Mon Sep 17 00:00:00 2001
From: Robert Curry <robert@silverstripe.com>
Date: Mon, 5 Aug 2013 15:43:35 +1200
Subject: [PATCH] Preempt fatal errors when making some function calls on an
 empty ArrayList

The function "first" on ArrayList uses the PHP function "reset", which
returns false if there aren't any elements in the array. Two functions
inside ArrayList use this function, "canFilterBy" and "byID". I've
changed these functions to catch the possibility of a false return from
first().
---
 model/ArrayList.php           | 12 ++++++++--
 tests/model/ArrayListTest.php | 42 +++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/model/ArrayList.php b/model/ArrayList.php
index 5a49bc1d8..d2fc2a156 100644
--- a/model/ArrayList.php
+++ b/model/ArrayList.php
@@ -404,7 +404,11 @@ class ArrayList extends ViewableData implements SS_List, SS_Filterable, SS_Sorta
 	 * It works by checking the fields available in the first record of the list.
 	 */
 	public function canFilterBy($by) {
-		return array_key_exists($by, $this->first());
+		$firstRecord = $this->first();
+		if ($firstRecord === false) {
+			return false;
+		}
+		return array_key_exists($by, $firstRecord);
 	}
 
 	/**
@@ -460,7 +464,11 @@ class ArrayList extends ViewableData implements SS_List, SS_Filterable, SS_Sorta
 	}
 	
 	public function byID($id) {
-		return $this->filter("ID", $id)->First();
+		$firstElement = $this->filter("ID", $id)->first();
+		if ($firstElement === false) {
+			return null;
+		}
+		return $firstElement;
 	}
 
 	/**
diff --git a/tests/model/ArrayListTest.php b/tests/model/ArrayListTest.php
index bbb57e75e..9953c5200 100644
--- a/tests/model/ArrayListTest.php
+++ b/tests/model/ArrayListTest.php
@@ -599,6 +599,48 @@ class ArrayListTest extends SapphireTest {
 		);
 		$this->assertEquals($expected, $list->toArray());
 	}
+
+	public function testCanFilterBy() {
+		$list = new ArrayList(array(
+			array('Name' => 'Steve'),
+			array('Name' => 'Bob'),
+			array('Name' => 'John')
+		));
+
+		$this->assertTrue($list->canFilterBy('Name'));
+		$this->assertFalse($list->canFilterBy('Age'));
+	}
+
+	public function testCanFilterByEmpty() {
+		$list = new ArrayList();
+
+		$this->assertFalse($list->canFilterBy('Name'));
+		$this->assertFalse($list->canFilterBy('Age'));
+	}
+
+	public function testByID() {
+		$list = new ArrayList(array(
+			array('ID' => 1, 'Name' => 'Steve'),
+			array('ID' => 2, 'Name' => 'Bob'),
+			array('ID' => 3, 'Name' => 'John')
+		));
+
+		$element = $list->byID(1);
+		$this->assertEquals($element['Name'], 'Steve');
+
+		$element = $list->byID(2);
+		$this->assertEquals($element['Name'], 'Bob');
+
+		$element = $list->byID(4);
+		$this->assertNull($element);
+	}
+
+	public function testByIDEmpty() {
+		$list = new ArrayList();
+
+		$element = $list->byID(1);
+		$this->assertNull($element);
+	}
 }
 
 /**