add existsOr and doesntExistOr to the querybuilder

src/Illuminate/Database/Query/Builder.php

@@ -2406,6 +2406,28 @@ public function doesntExist()
         return ! $this->exists();
     }
 
+    /**
+     * Execute the given callback if no rows exist for the current query.
+     *
+     * @param  \Closure $callback
+     * @return mixed
+     */
+    public function existsOr(Closure $callback)
+    {
+        return $this->exists() ? true : $callback();
+    }
+
+    /**
+     * Execute the given callback if rows exist for the current query.
+     *
+     * @param  \Closure $callback
+     * @return mixed
+     */
+    public function doesntExistOr(Closure $callback)
+    {
+        return $this->doesntExist() ? true : $callback();
+    }
+
     /**
      * Retrieve the "count" result of the query.
      *

tests/Database/DatabaseQueryBuilderTest.php

@@ -1825,6 +1825,38 @@ public function testSqlServerExists()
         $this->assertTrue($results);
     }
 
+    public function testExistsOr()
+    {
+        $builder = $this->getBuilder();
+        $builder->getConnection()->shouldReceive('select')->andReturn([['exists' => 1]]);
+        $results = $builder->from('users')->doesntExistOr(function () {
+            return 123;
+        });
+        $this->assertSame(123, $results);
+        $builder = $this->getBuilder();
+        $builder->getConnection()->shouldReceive('select')->andReturn([['exists' => 0]]);
+        $results = $builder->from('users')->doesntExistOr(function () {
+            throw new RuntimeException();
+        });
+        $this->assertTrue($results);
+    }
+
+    public function testDoesntExistsOr()
+    {
+        $builder = $this->getBuilder();
+        $builder->getConnection()->shouldReceive('select')->andReturn([['exists' => 0]]);
+        $results = $builder->from('users')->existsOr(function () {
+            return 123;
+        });
+        $this->assertSame(123, $results);
+        $builder = $this->getBuilder();
+        $builder->getConnection()->shouldReceive('select')->andReturn([['exists' => 1]]);
+        $results = $builder->from('users')->existsOr(function () {
+            throw new RuntimeException();
+        });
+        $this->assertTrue($results);
+    }
+
     public function testAggregateResetFollowedByGet()
     {
         $builder = $this->getBuilder();