Overwrite Laravel base query builder exists method

Fix #607

Author: alexandre-butynski

src/Jenssegers/Mongodb/Query/Builder.php

@@ -349,6 +349,16 @@ public function aggregate($function, $columns = [])
         }
     }
 
+    /**
+     * Determine if any rows exist for the current query.
+     *
+     * @return bool
+     */
+    public function exists()
+    {
+        return ! is_null($this->first());
+    }
+
     /**
      * Force the query to only return distinct results.
      *

tests/QueryTest.php

@@ -206,6 +206,12 @@ public function testCount()
         $this->assertEquals(6, $count);
     }
 
+    public function testExists()
+    {
+        $this->assertFalse(User::where('age', '>', 37)->exists());
+        $this->assertTrue(User::where('age', '<', 37)->exists());
+    }
+
     public function testSubquery()
     {
         $users = User::where('title', 'admin')->orWhere(function ($query)