Plug'n'play filter trait for filtering resources in your controllers

FiltersRequests.php

<?php

namespace App\Http;

/**
 * ?filter[foo]=bar&filter[qux]=baz
 */
trait FiltersRequests
{
    private function filter($query)
    {
        foreach (request('filter') as $attribute => $value) {
            if (! $filterMethod = $this->toFilter($query, $attribute)) {
                continue;
            }
            $this->$filterMethod($query, $value, $attribute);
        }
    }

    private function toFilter($query, $attribute) {
        $filterMethod = sprintf('filter%s', studly_case($attribute));
        if ($this->hasFilter($filterMethod)) {
            return $filterMethod;
        }

        if ($this->hasScopeFor($query->getModel(), $attribute)) {
            return 'filterUsingScope';
        }

        return null;
    }

    private function hasScopeFor($model, $attribute) {
        return method_exists($model, sprintf('scope%s', ucfirst($attribute)));
    }

    private function filterUsingScope($query, $value, $attribute)
    {
        $scope = sprintf('scope%s', ucfirst($attribute));
        return $query->getModel()->$scope($query, $value);
    }

    private function hasFilter($filterMethod)
    {
        return method_exists($this, $filterMethod);
    }
}