From 9006daf20bfb5cebc224e03766c2cff136d33b6a Mon Sep 17 00:00:00 2001
From: Daniel Hensby <dhensby@silverstripe.com>
Date: Wed, 28 Feb 2018 13:25:28 +0000
Subject: [PATCH] Cleaning up PR and adding tests

---
 src/ORM/DataObject.php           | 20 +++++++++++---------
 tests/php/ORM/DataObjectTest.php | 14 ++++++++++++++
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/src/ORM/DataObject.php b/src/ORM/DataObject.php
index b5ba2a2e8..7451422ce 100644
--- a/src/ORM/DataObject.php
+++ b/src/ORM/DataObject.php
@@ -3175,22 +3175,24 @@ class DataObject extends ViewableData implements DataObjectInterface, i18nEntity
     /**
      * Return the given element, searching by ID
      *
-     * @param string $callerClass The class of the object to be returned (optional if called from extending class)
-     * @param int $id The id of the element
-     * @param boolean $cache See {@link get_one()}
+     * @param string|int $callerClassOrID The class of the object to be returned (optional if called from extending class)
+     * @param int|bool $id The id of the element or bool to represent cache if ID is passed as fist argument
+     * @param bool $cache See {@link get_one()}
      *
-     * @return DataObject The element
+     * @return static The element
      */
-    public static function get_by_id($callerClass, $id = null, $cache = true)
+    public static function get_by_id($callerClassOrID, $id = null, $cache = true)
     {
-        if(is_numeric($callerClass)) {
+        if (is_numeric($callerClassOrID)) {
             // Alternate signature to allow calling as MyDataObject::get_by_id($id)
-            $cache = is_null($id) ? true : !!$id;
-            $id = $callerClass;
+            $cache = is_null($id) ? true : (bool)$id;
+            $id = $callerClassOrID;
             $callerClass = get_called_class();
-            if (__CLASS__ === $callerClass) {
+            if (__CLASS__ === $callerClassOrID) {
                 user_error("DataObject::get_by_id called without providing object class", E_USER_WARNING);
             }
+        } else {
+            $callerClass = $callerClassOrID;
         }
 
         if (!is_numeric($id)) {
diff --git a/tests/php/ORM/DataObjectTest.php b/tests/php/ORM/DataObjectTest.php
index 606075f5b..7a9422abf 100644
--- a/tests/php/ORM/DataObjectTest.php
+++ b/tests/php/ORM/DataObjectTest.php
@@ -324,6 +324,20 @@ class DataObjectTest extends SapphireTest
         $this->assertEquals('Phil', $comment->Name);
     }
 
+    public function testGetByIDCallerClass()
+    {
+        $captain1ID = $this->idFromFixture(DataObjectTest\Player::class, 'captain1');
+        $captain1 = DataObjectTest\Player::get_by_id($captain1ID);
+        $this->assertInstanceOf(DataObjectTest\Player::class, $captain1);
+        $this->assertEquals('Captain', $captain1->FirstName);
+
+        $captain2ID = $this->idFromFixture(DataObjectTest\Player::class, 'captain2');
+        // make sure we can call from any class but get the one passed as an argument
+        $captain2 = DataObjectTest\TeamComment::get_by_id(DataObjectTest\Player::class, $captain2ID);
+        $this->assertInstanceOf(DataObjectTest\Player::class, $captain2);
+        $this->assertEquals('Captain 2', $captain2->FirstName);
+    }
+
     public function testGetCaseInsensitive()
     {
         // Test get_one() with bad case on the classname