From b7ac667405de382b504346ff30a42fb9acb82550 Mon Sep 17 00:00:00 2001
From: Taylor Otwell <taylorotwell@gmail.com>
Date: Tue, 17 Apr 2012 14:33:17 -0500
Subject: [PATCH] tweak belongs to eager constraining.

---
 laravel/database/eloquent/relationships/belongs_to.php | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/laravel/database/eloquent/relationships/belongs_to.php b/laravel/database/eloquent/relationships/belongs_to.php
index b73c57bf..ff0d29d5 100644
--- a/laravel/database/eloquent/relationships/belongs_to.php
+++ b/laravel/database/eloquent/relationships/belongs_to.php
@@ -65,7 +65,10 @@ public function eagerly_constrain($results)
 		// are looking for the parent of a child model in this relationship.
 		foreach ($results as $result)
 		{
-			$keys[] = $result->{$this->foreign_key()};
+			if ( ! is_null($key = $result->{$this->foreign_key()}))
+			{
+				$keys[] = $key;
+			}
 		}
 
 		$this->table->where_in($this->model->key(), array_unique($keys));