By default do not run methods that have empty value

src/Filter.php

@@ -21,6 +21,14 @@ abstract class Filter
      */
     protected $builder;
 
+    /**
+     * Specify method names, which should be run
+     * even when the value is with length of 0.
+     *
+     * @var array
+     */
+    protected $alwaysRun = [];
+
     /**
      * @param Request $request
      */
@@ -46,6 +54,10 @@ public function apply(Builder $builder)
                 continue;
             }
 
+            if(! $this->shouldRunMethod($name, $value)) {
+                continue;
+            }
+
             call_user_func([$this, $name], $value);
         }
 
@@ -85,4 +97,14 @@ public function sort(array $sort)
 
         return $builder;
     }
+
+    /**
+     * @param $method
+     * @param $value
+     * @return bool
+     */
+    protected function shouldRunMethod($method, $value)
+    {
+        return in_array($method, $this->alwaysRun) || strlen($value) > 0;
+    }
 }