UrlHelper

Zend\Expressive\Helper\UrlHelper provides the ability to generate a URI path based on a given route defined in the Zend\Expressive\Router\RouterInterface. If injected with a route result, and the route being used was also the one matched during routing, you can provide a subset of routing parameters, and any not provided will be pulled from those matched.

Usage

When you have an instance, use either its generate() method, or call the instance as an invokable:

// Using the generate() method:
$url = $helper->generate('resource', ['id' => 'sha1']);

// is equivalent to invocation:
$url = $helper('resource', ['id' => 'sha1']);

The signature for both is:

function (
    $routeName,
    array $routeParams = [],
    $queryParams = [],
    $fragmentIdentifier = null,
    array $options = []
) : string

Where:

  • $routeName is the name of a route defined in the composed router. You may omit this argument if you want to generate the path for the currently matched request.
  • $routeParams is an array of substitutions to use for the provided route, with the following behavior:
    • If a RouteResult is composed in the helper, and the $routeName matches it, the provided $params will be merged with any matched parameters, with those provided taking precedence.
    • If a RouteResult is not composed, or if the composed result does not match the provided $routeName, then only the $params provided will be used for substitutions.
    • If no $params are provided, and the $routeName matches the currently matched route, then any matched parameters found will be used. parameters found will be used.
    • If no $params are provided, and the $routeName does not match the currently matched route, or if no route result is present, then no substitutions will be made.
  • $queryParams is an array of query string arguments to include in the generated URI.
  • $fragmentIdentifier is a string to use as the URI fragment.
  • $options is an array of options to provide to the router for purposes of controlling URI generation. As an example, zend-router can consume "translator" and "text_domain" options in order to provide translated URIs.

Each method will raise an exception if:

  • No $routeName is provided, and no RouteResult is composed.
  • No $routeName is provided, a RouteResult is composed, but that result represents a matching failure.
  • The given $routeName is not defined in the router.

Signature changes

The signature listed above is current as of version 3.0.0 of zendframework/zend-expressive-helpers. Prior to that version, the helper only accepted the route name and route parameters.

Registering the pipeline middleware

For the UrlHelper to work, you must first register the UrlHelperMiddleware as pipeline middleware following the routing middleware, and before the dispatch middleware:

use Zend\Expressive\Helper\UrlHelperMiddleware;

// Programmatically:
$app->pipe(RouteMiddleware::class);
// ...
$app->pipe(UrlHelperMiddleware::class);
$app->pipe(DispatchMiddleware::class);

Skeleton configures helpers

If you started your project using the Expressive skeleton package, the UrlHelper and UrlHelperMiddleware factories are already registered for you, as is the UrlHelperMiddleware pipeline middleware.

Using the helper in middleware

Compose the helper in your middleware (or elsewhere), and then use it to generate URI paths:

<?php
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;
use Zend\Expressive\Helper\UrlHelper;

class FooMiddleware implements MiddlewareInterface
{
    private $helper;

    public function __construct(UrlHelper $helper)
    {
        $this->helper = $helper;
    }

    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler) : ResponseInterface
    {
        $response = $handler->handle($request);
        return $response->withHeader(
            'Link',
            $this->helper->generate('resource', ['id' => 'sha1'])
        );
    }
}

Base Path support

If your application is running under a subdirectory, or if you are running pipeline middleware that is intercepting on a subpath, the paths generated by the router may not reflect the base path, and thus be invalid. To accommodate this, the UrlHelper supports injection of the base path; when present, it will be prepended to the path generated by the router.

As an example, perhaps you have middleware running to intercept a language prefix in the URL; this middleware could then inject the UrlHelper with the detected language, before stripping it off the request URI instance to pass on to the router:

<?php
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;
use Zend\Expressive\Helper\UrlHelper;

class LocaleMiddleware implements MiddlewareInterface
{
    private $helper;

    public function __construct(UrlHelper $helper)
    {
        $this->helper = $helper;
    }

    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler) : ResponseInterface
    {
        $uri = $request->getUri();
        $path = $uri->getPath();
        if (! preg_match('#^/(?P<locale>[a-z]{2,3}([-_][a-zA-Z]{2}|))/#', $path, $matches)) {
            return $handler->handle($request);
        }

        $locale = $matches['locale'];
        Locale::setDefault(Locale::canonicalize($locale));
        $this->helper->setBasePath($locale);

        return $handler->handle($request->withUri(
            $uri->withPath(substr($path, strlen($locale) + 1))
        ));
    }
}

(Note: if the base path injected is not prefixed with /, the helper will add the slash.)

Paths generated by the UriHelper from this point forward will have the detected language prefix.

Found a mistake or want to contribute to the documentation? Edit this page on GitHub!