A PSR-15 middleware class to normalize query parameters (e.g. to turn a "true" or a "false" string from a query parameter to a boolean true or false for the next middlewares/handlers in the pipeline.

NormalizeQueryParamsMiddleware.php

<?php

declare(strict_types=1);

namespace Application\Middleware;

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;

class NormalizeQueryParamsMiddleware implements MiddlewareInterface
{
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler) : ResponseInterface
    {
        return $handler->handle(
            $request->withQueryParams(
                $this->normalize(
                    $request->getQueryParams()
                )
            )
        );
    }

    private function normalize($value)
    {
        if ($value === 'true') {
            return true;
        }

        if ($value === 'false') {
            return false;
        }

        if (is_array($value)) {
            $newValue = [];

            foreach ($value as $childKey => $childValue) {
                $newValue[$childKey] = $this->normalize($childValue);
            }

            return $newValue;
        }

        return $value;
    }
}

Nice idea, but why don't you just use the Laminas filter?

Edit: Or at least, I'd add normalization for '0' and '1', too.

@rieschl I think installing laminas-filter when I just need to convert string 'true' and string 'false' to bool true and bool false respectively is an overkill. I would argue against normalizing string '0' and string '1', as there could be another parameter that we want to be a string of zero or a string of one, e.g. consider an implementation that uses the query for filtering results and you have a minimum and maximum values. But I would rather extend the current gist to support numeric values by casting them to integers or floats respectively.