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Migration

Migration to Mezzio 2.0

Mezzio 2.0 should not result in many upgrade problems for users. However, starting in this version, we offer a few changes affecting the following that you should be aware of, and potentially update your application to adopt:

Signature changes

The following signature changes were made that could affect class extensions:

  • Mezzio\Application::__call($method, array $args): previously, the $args argument was not typehinted; it now is. If you are extending this class and overriding that method, you will need to update your method signature accordingly.

Additionally, a number of signatures change due to updating Mezzio to support PSR-11 instead of container-interop (which was the basis for PSR-11). Essentially, these were a matter of updating typehints on Interop\Container\ContainerInterface to Psr\Container\ContainerInterface. Signatures affected include:

  • Mezzio\AppFactory::create()
  • Mezzio\Application::__construct()
  • Mezzio\Container\ApplicationFactory::__invoke()
  • Mezzio\Container\ErrorHandlerFactory::__invoke()
  • Mezzio\Container\ErrorResponseGeneratorFactory::__invoke()
  • Mezzio\Container\NotFoundDelegateFactory::__invoke()
  • Mezzio\Container\NotFoundHandlerFactory::__invoke()
  • Mezzio\Container\WhoopsErrorResponseGeneratorFactory::__invoke()
  • Mezzio\Container\WhoopsFactory::__invoke()
  • Mezzio\Container\WhoopsPageHandlerFactory::__invoke()

In each of the above cases, updating your import statements from Interop\Container\ContainerInterface to Psr\Container\ContainerInterface will make your code work again.

The following exceptions now implement PSR-11 exception interfaces instead of container-interop variants:

  • Mezzio\Container\Exception\InvalidServiceException

In the above case, if you were previously catching the container-interop exception on which it was based, your code should still work so long as you have container-interop installed. You should likely update it to catch the more general Psr\Container\ContainerExceptionInterface instead, however.

Removed functionality

The following classes and/or methods were removed for the Mezzio 2.0 release:

  • Mezzio\Application::pipeErrorHandler(). Stratigility 2.0 dropped its ErrorMiddlewareInterface and the concept of error middleware (middleware supporting an additional $error argument in its signature); this method was thus no longer relevant.

  • Mezzio\Application::routeMiddleware(). Routing middleware was extracted to the class Mezzio\Middleware\RouteMiddleware.

  • Mezzio\Application::dispatchMiddleware(). Dispatch middleware was extracted to the class Mezzio\Middleware\DispatchMiddleware.

  • Mezzio\Application::getFinalHandler(). Stratigility 2 supports the http-interop/http-middleware project, and now uses delegates. This method was renamed to getDefaultDelegate(), and now returns an Interop\Http\ServerMiddleware\DelegateInterface instance.

  • Mezzio\Container\Exception\InvalidArgumentException. This exception was thrown by Mezzio\Container\ApplicationFactory previously; that class now throws Mezzio\Exception\InvalidArgumentException instead.

  • Mezzio\Container\Exception\NotFoundException. This exception type was never used internally.

  • Mezzio\ErrorMiddlewarePipe. With the removal of Stratigility 1 error middleware, this specialized MiddlewarePipe no longer has any use.

  • Mezzio\Container\TemplatedErrorHandlerFactory. See the section on final handler changes for more information.

  • Mezzio\Container\WhoopsErrorHandlerFactory. See the section on final handler changes for more information.

  • Mezzio\TemplatedErrorHandler. See the section on final handler changes for more information.

  • Mezzio\WhoopsErrorHandler. See the section on final handler changes for more information.

Deprecated functionality

  • Mezzio\Application::raiseThrowables(). Stratigility 2.0 makes the method a no-op, as exceptions are no longer caught by the middleware dispatcher. As such, the raise_throwables configuration argument now is no longer used, either.

PSR-11 support

In previous versions of Mezzio, we consumed container-interop, which provides Interop\Container\ContainerInterface, a shared interface for dependency injection containers. container-interop served as a working group for the PSR-11 specification.

In the weeks prior to the Mezzio 2.0 release, PSR-11 was formally accepted, and the package psr/container was released. As such, we have updated Mezzio to consume the interfaces PSR-11 exposes.

No supported implementations currently directly implement PSR-11, however. Fortunately, the container-interop 1.2.0 release acts as a forwards-compatibility measure by altering every interface it exposes to extend those from PSR-11, making existing container-interop implementations de facto PSR-11 implementations!

The result is a (mostly) transparent upgrade for users of Mezzio. As newer versions of container implementations are released supporting PSR-11 directly, you will be able to upgrade immediately; we will also periodically update the skeleton to pick up these new versions when present. (The one caveat to upgrading is signature changes within Mezzio classes based on the new psr/container interface names.)

As long as you have container-interop 1.2.0 installed, your existing factories that typehint against its interface will continue to work. However, we recommend updating them to instead typehint against PSR-11, which will allow you to drop the container-interop requirement once your chosen container implementation no longer requires it.

Do not update blindly

If you are implementing interfaces from other packages in your factory implementations, be sure to check and see if those interfaces update to PSR-11 before making changes.

As an example, laminas-servicemanager v3 does not update Laminas\ServiceManager\Factory\FactoryInterface and siblings to typehint against PSR-11, as doing so would break backwards compatibility.

http-interop

Stratigility 2.0 provides the ability to work with http-interop middleware 0.4.1.

This specification, which is being developed as the basis of PSR-15, defines what is known as lambda or single-pass middleware, vs the double-pass middleware traditionally used by Stratigility and Mezzio.

Double-pass refers to the fact that two arguments are passed to the delegation function $next: the request and response. Lambda or single-pass middleware only pass a single argument, the request.

Stratigility 2.0 provides support for dispatching either style of middleware.

Specifically, your middleware can now implement:

  • Interop\Http\ServerMiddleware\MiddlewareInterface, which defines a single method, process(Psr\Http\Message\ServerRequestInterface $request, Interop\Http\ServerMiddleware\DelegateInterface $delegate).
  • Callable middleware that follows the above signature (the typehint for the request argument is optional).

Both styles of middleware may be piped directly to the middleware pipeline or as routed middleware within Mezzio. In each case, you can invoke the next middleware layer using $delegate->process($request).

In Mezzio 2.0, Application will continue to accept the legacy double-pass signature, but will require that you either:

  • Provide a $responsePrototype (a ResponseInterface instance) to the Application instance prior to piping or routing such middleware.
  • Decorate the middleware in a Laminas\Stratigility\Middleware\CallableMiddlewareWrapper instance (which also requires a $responsePrototype).

If you use Mezzio\Container\ApplicationFactory to create your Application instance, a response prototype will be injected for you from the outset.

We recommend that you begin writing middleware to follow the http-interop standard at this time. As an example:

namespace App\Middleware;

use Interop\Http\ServerMiddleware\DelegateInterface;
use Interop\Http\ServerMiddleware\MiddlewareInterface;
use Psr\Http\Message\ServerRequestInterface;

class XClacksOverheadMiddleware implements MiddlewareInterface
{
    /**
     * {@inheritDoc}
     */
    public function process(ServerRequestInterface $request, DelegateInterface $delegate)
    {
        $response = $delegate->process($request);
        return $response->withHeader('X-Clacks-Overhead', 'GNU Terry Pratchett');
    }
}

Alternately, you can write this as a callable:

namespace App\Middleware;

use Interop\Http\ServerMiddleware\DelegateInterface;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;

class XClacksOverheadMiddleware
{
    /**
     * @param ServerRequestInterface $request
     * @param DelegateInterface $delegate
     * @return ResponseInterface
     */
    public function __invoke(ServerRequestInterface $request, DelegateInterface $delegate)
    {
        $response = $delegate->process($request);
        return $response->withHeader('X-Clacks-Overhead', 'GNU Terry Pratchett');
    }
}

Original messages

In the migration to version 1.1 guide, we detail the fact that Stratigility 1.3 deprecated its internal request and response decorators. Stratigility 2.0, on which Mezzio 2.0 is based, removes them entirely.

If your code relied on the various getOriginal*() methods those decorators exposed, you will need to update your code in two ways:

  • You will need to add Laminas\Stratigility\Middleware\OriginalMessages to your middleware pipeline, as the outermost (or close to outermost) layer.
  • You will need to update your code to call on the request instance's getAttribute() method with one of originalRequest, originalUri, or originalResponse to retrieve the values.

To address the first point, see the Mezzio 1.1 migration documentation, which details how to update your configuration or programmatic pipeline.

For the second point, we provide a tool via the mezzio/mezzio-tooling package which will help you in this latter part of the migration. Install it as a development requirement via composer:

$ composer require --dev mezzio/mezzio-tooling

And then execute it via:

$ ./vendor/bin/mezzio-migrate-original-messages

This tool will update calls to getOriginalRequest() and getOriginalUri() to instead use the new request attributes that the OriginalMessages middleware injects:

  • getOriginalRequest() becomes getAttribute('originalRequest', $request)
  • getOriginalUri() becomes getAttribute('originalUri', $request->getUri())

In both cases, $request will be replaced with whatever variable name you used for the request instance.

For getOriginalResponse() calls, which happen on the response instance, the tool will instead tell you what files had such calls, and detail how you can update those calls to use the originalResponse request attribute.

Error handling

As noted in the Mezzio 1.1 migration docs, Stratigility 1.3 introduced the ability to tell it to no longer catch exceptions internally, paving the way for middleware-based error handling. Additionally, it deprecated its own ErrorMiddlewareInterface and duck-typed implementations of the interface in favor of middleware-based error handling. Finally, it deprecated the $e/$error argument to "final handlers", as that argument would be used only when attempting to invoke ErrorMiddlewareInterface instances.

Stratigility 2.0, on which Mezzio 2.0 is based, no longer catches exceptions internally, removes the ErrorMiddlewareInterface entirely, and thus the $e/$error argument to final handlers.

As such, you MUST provide your own error handling with Mezzio 2.0.

Error handling middleware will typically introduce a try/catch block:

function (
    ServerRequestInterface $request,
    ResponseInterface $response,
    callable $next
) {
    try {
        $response = $next($request, $response);
        return $response;
    } catch (\Throwable $exception) {
        // caught PHP 7 throwable
    } catch (\Exception $exception) {
        // caught PHP 5 exception
    }

    // ...
    // do something with $exception and generate a response
    // ...

    return $response;
}

Additionally, you will need middleware registered as your innermost layer that is guaranteed to return a response. Generally, if you hit that layer, no other middleware is capable of handling the request, indicating a 400 (Bad Request) or 404 (Not Found) HTTP status. With the combination of an error handler at the outermost layer, and a "not found" handler at the innermost layer, you can handle any error in your application.

Stratigility 1.3 and 2.0 provide an error handler implementation via Laminas\Stratigility\Middleware\ErrorHandler. In addition to the try/catch block, it also sets up a PHP error handler that will catch any PHP error types in the current error_reporting mask; the error handler will raise exceptions of the type ErrorException with the PHP error details.

ErrorHandler allows injection of an "error response generator", which allows you to alter how the error response is generated based on the current environment. Error response generators are callables with the signature:

function (
    Throwable|Exception $e,
    ServerRequestInterface $request,
    ResponseInterface $response
) : ResponseInterface

Mezzio 2.0 provides the following functionality to assist with your error handling needs:

  • Mezzio\Middleware\ErrorResponseGenerator will output a canned plain/text message, or use a supplied template renderer to generate content for the response. It accepts the following arguments to its constructor:

    • $isDevelopmentMode = false: whether or not the application is in development mode. If so, it will output stack traces when no template renderer is used (see below), or supply the exception to the template via the error variable if a renderer is present.

    • Mezzio\Template\TemplateRendererInterface $renderer: if supplied, the results of rendering a template will be injected into the response. Templates are passed the following variables:

      • response: the response at the time of rendering
      • request: the request at the time of rendering
      • uri: the URI at the time of rendering
      • status: the response status code
      • reason: the response reason phrase
      • error: the exception; this is only provided when in development mode.

    • $template = 'error::error': the template to render, with a default value if none is provided.

  • Mezzio\Container\ErrorResponseGeneratorFactory can create an instance of the ErrorResponseGenerator using the following:

    • The debug top-level configuration value is used to set the $isDevelopmentMode flag.

    • If a Mezzio\Template\TemplateRendererInterface service is registered, it will be provided to the constructor.

    • The value of mezzio.error_handler.template_error, if present, will be used to seed the $template argument.

  • Mezzio\Middleware\WhoopsErrorResponseGenerator uses Whoops to generate the error response. Its constructor takes a single argument, a Whoops\Run instance. If a Whoops\Handler\PrettyPageHandler is registered with the instance, it will add a data table with request details derived from the ServerRequestInterface instance.

Mezzio\Container\WhoopsErrorResponseGeneratorFactory can create an instance, and will use the Mezzio\Whoops service to seed the Whoops\Run argument.

  • Mezzio\Middleware\NotFoundHandler can be used as the innermost layer of your pipeline in order to return a 404 response. (Typically, if you get to the innermost layer, no middleware was able to handle the request, indicating a 404.) By default, it will produce a canned plaintext response. However, you can also provide an optional TemplateRendererInterface instance and $template in order to provide templated content.

The constructor arguments are:

- `ResponseInterface $responsePrototype`: this is an empty response on which
  to set the 404 status and inject the 404 content.

- `TemplateRendererInterface $renderer`: optionally, you may provide a
  renderer to use in order to provide templated response content.

- $template = 'error::404'`: optionally, you may provide a
  template to render; if none is provided, a sane default is used.

  • Mezzio\Container\NotFoundHandlerFactory can create an instance of the NotFoundHandler for you, and will use the following to do so:

    • The Mezzio\Template\TemplateRendererInterface service, if available.

    • The mezzio.error_handler.template_404 configuration value, if available, will be used for the $template.

  • Mezzio\Container\ErrorHandlerFactory will create an instance of Laminas\Stratigility\Middleware\ErrorHandler, and use the Laminas\Stratigility\Middleware\ErrorResponseGenerator service to seed it.

As such, register one of the following as a factory for the Laminas\Stratigility\Middleware\ErrorResponseGenerator service: - Mezzio\Container\ErrorResponseGeneratorFactory - Mezzio\Container\WhoopsErrorResponseGeneratorFactory

Error handler configuration example

If you are using configuration-driven middleware, your middleware pipeline configuration may look like this in order to make use of the new error handling facilities:

// config/autoload/middleware-pipeline.global.php

use Mezzio\Application;
use Mezzio\Container;
use Mezzio\Helper;
use Mezzio\Middleware;
use Laminas\Stratigility\Middleware\ErrorHandler;
use Laminas\Stratigility\Middleware\OriginalMessages;

return [
    // Add the following section to enable the new error handling:
    'mezzio' => [
        'raise_throwables' => true,
    ],

    'dependencies' => [
        'invokables' => [
            // See above section on "Original messages":
            OriginalMessages::class => OriginalMessages::class,
        ],
        'factories' => [
            Helper\ServerUrlMiddleware::class => Helper\ServerUrlMiddlewareFactory::class,
            Helper\UrlHelperMiddleware::class => Helper\UrlHelperMiddlewareFactory::class,

            // Add the following three entries:
            ErrorHandler::class => Container\ErrorHandlerFactory::class,
            Middleware\ErrorResponseGenerator::class => Container\ErrorResponseGeneratorFactory::class,
            Middleware\NotFoundHandler::class => Container\NotFoundHandlerFactory::class,
        ],
    ],

    'middleware_pipeline' => [
        'always' => [
            'middleware' => [
                OriginalMessages::class,
                Helper\ServerUrlMiddleware::class,
                ErrorHandler::class,
                /* ... */
            ],
            'priority' => 10000,
        ],

        'routing' => [
            'middleware' => [
                Application::ROUTING_MIDDLEWARE,
                Helper\UrlHelperMiddleware::class,
                Application::DISPATCH_MIDDLEWARE,
            ],
            'priority' => 1,
        ],

        'not-found' => [
            'middleware' => Middleware\NotFoundHandler::class,
            'priority' => 0,
        ],

        // Remove the section "error""
    ],
];

If you are defining a programmatic pipeline (see more below on this), the pipeline might look like:

$app->pipe(OriginalMessages::class);
$app->pipe(Helper\ServerUrlMiddleware::class);
$app->pipe(ErrorHandler::class);
$app->pipeRoutingMiddleware();
$app->pipe(Helper\UrlHelperMiddleware::class);
$app->pipeDispatchMiddleware();
$app->pipe(Middleware\NotFoundHandler::class);

Error handling and PHP errors

As noted above, Laminas\Stratigility\Middleware\ErrorHandler also creates a PHP error handler that casts PHP errors to ErrorException instances. More specifically, it uses the current error_reporting value to determine which errors it should cast this way.

This can be problematic when deprecation errors are triggered. If they are cast to exceptions, code that would normally run will now result in error pages.

We recommend adding the following line to your public/index.php towards the top of the file:

error_reporting(error_reporting() & ~E_USER_DEPRECATED);

This will prevent the error handler from casting deprecation notices to exceptions, while keeping the rest of your error reporting mask intact.

Removing legacy error middleware

Stratigility version 1-style error middleware (middleware implementing Laminas\Stratigility\ErrorMiddlewareInterface, or duck-typing its signature, which included an $error argument as the first argument to the middleware) is no longer supported with Stratigility version 2 and Mezzio 2.0. You will need to find any instances of them in your application, or cases where your middleware invokes error middleware via the third argument to $next().

We provide a tool to assist you with that via the package mezzio/mezzio-tooling: vendor/bin/mezzio-scan-for-error-middleware. Run the command from your project root, optionally passing the help, --help, or -h commands for usage. The tool will detect each of these for you, flagging them for you to update or remove.

Final handlers become default delegates

One ramification of supporting http-interop middleware is that the concept of "final handlers" changes. In Stratigility 1.X and Mezzio 1.X, a "final handler" was invoked when the middleware pipeline was exhausted; however, due to how Stratigility caught exceptions, this also meant that the final handler often acted as the application error handler, reporting errors to end users.

With the error handling changes noted above, error handling is moved to dedicated middleware. However, there is still a need to have something that can execute once the middleware pipeline is exhausted. Such a situation typically indicates no middleware was able to handle the request, or that the request was somehow malformed.

In Mezzio 2.0, we have removed final handlers, and replaced them with the concept of "default delegates". Delegates are Interop\Http\ServerMiddleware\DelegateInterface instances, which are invoked by middleware when they wish to delegate processing of the request to something else. Internally, Stratigility 2.0 and Mezzio 2.0 use a delegate to iterate through the middleware pipeline. For Mezzio 2.0, a default delegate is a delegate executed when the application's internal middleware pipeline is exhausted.

The ramifications for end users are as follows:

  • The $finalHandler argument to Application's constructor, which previously was a callable, is now called $defaultDelegate, and needs to be a DelegateInterface instance.

  • getFinalHandler() no longer exists; we have added getDefaultDelegate().

  • The service Mezzio\FinalHandler is no longer used. A new service, Mezzio\Delegate\DefaultDelegate, is used by ApplicationFactory, and, if present, will be used to inject the $defaultDelegate argument of the Application constructor.

  • We have removed the following classes, which either provided final handlers, or acted as factories for them:

    • Mezzio\TemplatedErrorHandler
    • Mezzio\WhoopsErrorHandler
    • Mezzio\Container\TemplatedErrorHandlerFactory
    • Mezzio\Container\WhoopsErrorHandlerFactory

If you use the vendor/bin/mezzio-pipeline-from-config tool to migrate your application to programmatic pipelines, as described below, the DefaultDelegate service will be mapped to Mezzio\Container\NotFoundDelegateFactory, which will provide an instance of Mezzio\Delegate\NotFoundDelegate. This new class will produce a 404 response, using a template if the Mezzio\Template\TemplateRendererInterface service is present, but otherwise producing a plain text response.

Application's built using the 2.0 version of the skeleton application will have these features enabled by default.

NotFoundDelegate and NotFoundHandler

Mezzio\Middleware\NotFoundHandler, which is intended as innermost middleware for producing a 404 response, composes and proxies to a NotFoundDelegate instance to produce its response.

Programmatic middleware pipelines

Starting with Mezzio 1.1, we recommended programmatic creation of pipelines and routing; the Mezzio 1.1 migration guide provides more detail.

With Mezzio 2.0, this is now the default option shipped in the skeleton.

If you are upgrading from version 1 and are not currently using programmatic pipelines, we provide a migration tool that will convert your application to do so. The tool is available via the package mezzio/mezzio-tooling. You may install this package in one of the following ways:

  • Via the vendor binary ./vendor/bin/mezzio-tooling:
$ ./vendor/bin/mezzio-tooling        # install
$ ./vendor/bin/mezzio-tooling remove # uninstall
  • Using Composer:
$ composer require --dev mezzio/mezzio-tooling # install
$ composer remove --dev mezzio/mezzio-tooling  # uninstall

Once installed, you will use the vendor/bin/mezzio-pipeline-from-config command.

This command does the following:

  • Reads your middleware_pipeline configuration, and generates a programmatic pipeline for you, which is then stored in config/pipeline.php. The generated pipeline contains the following additions:

    • The first middleware in the pipeline is Laminas\Stratigility\Middleware\OriginalMessages, which injects the incoming request, URI, and response as the request attributes originalRequest, originalUri, and originalResponse, respectively. (This can aid URI generation in nested middleware later.)

    • The second middleware in the pipeline is Laminas\Stratigility\Middleware\ErrorHandler.

    • The last middleware in the pipeline is Mezzio\Middleware\NotFoundHandler.

  • Reads your routes configuration, and generates a programmatic routing table for you, which is then stored in config/routes.php.

  • Adds a new configuration file, config/autoload/programmatic-pipeline.global.php, which enables the programmatic_pipelines configuration flag. Additionally, it adds dependency configuration for the new error handlers.

  • Inserts two lines before the $app->run() statement of your public/index.php, one each to require config/pipeline.php and config/routes.php.

Your middleware_pipeline and routes configuration are not removed at this time, to allow you to test and verify your application first; however, due to the configuration in config/autoload/programmatic-pipeline.global.php, these are now ignored.

If you wish to use Whoops in your development environment, you may add the following to a local configuration file (e.g., config/autoload/local.php):

use Mezzio\Container\WhoopsErrorResponseGeneratorFactory;
use Mezzio\Middleware\ErrorResponseGenerator;

return [
    'dependencies' => [
        'factories' => [
            ErrorResponseGenerator::class => WhoopsErrorResponseGeneratorFactory::class,
        ],
    ],
];

Other things you may want to do:

  • The ErrorHandler entry could potentially be moved inwards a few layers. As an example, the ServerUrlMiddleware has no possibility of raising an exception or error, and could be moved outwards; you could do similarly for any middleware that only injects additional response headers.

  • Remove any Stratigility-style error middleware (middleware expecting an error as the first argument). If any specialized error handling should occur, add additional middleware into the pipeline that can catch exceptions, and have that middleware re-throw for exceptions it cannot handle. (Use the vendor/bin/mezzio-scan-for-error-middleware command from mezzio/mezzio-tooling to assist in this.)

  • Consider providing your own Laminas\Stratigility\NoopFinalHandler implementation; this will now only be invoked if the queue is exhausted, and could return a generic 404 page, raise an exception, etc.

Handling HEAD and OPTIONS requests

Prior to 2.0, it was possible to route middleware that could not handle HEAD and/or OPTIONS requests. Per RFC 7231, section 4.1, "all general-purpose servers MUST support the methods GET and HEAD. All other methods are OPTIONAL." Additionally, most servers and implementors agree that OPTIONS should be supported for any given resource, so that consumers can determine what methods are allowed for the given resource.

To make this happen, the Mezzio project implemented several features.

First, mezzio-router 1.3.0 introduced several features in both Mezzio\Router\Route and Mezzio\Router\RouteResult to help consumers implement support for HEAD and OPTIONS in an automated way. The Route class now has two new methods, implicitHead() and implicitOptions(); these each return a boolean true value if support for those methods is implicit — i.e., not defined explicitly for the route. The RouteResult class now introduces a new factory method, fromRoute(), that will create an instance from a Route instance; this then allows consumers of a RouteResult to query the Route to see if a matched HEAD or OPTIONS request needs automated handling. Each of the supported router implementations were updated to use this method, as well as to return a successful routing result if HEAD and/or OPTIONS requests are submitted, but the route does not explicitly support the method.

Within Mezzio itself, we now offer two new middleware to provide this automation:

  • Mezzio\Middleware\ImplicitHeadMiddleware
  • Mezzio\Middleware\ImplicitOptionsMiddleware

If you want to support these methods automatically, each of these should be enabled between the routing and dispatch middleware. If you use the mezzio-pipeline-from-config tool as documented in the programmatic pipeline migration section, entries for each will be injected into your generated pipeline.

Please see the chapter on the implicit methods middleware for more information on each.

Router interface changes

Mezzio 2.0 uses mezzio/mezzio-router 2.1+. Version 2.0 of that package introduced a change to the Mezzio\Router\RouterInterface::generateUri() method; it now accepts an additional, optional, third argument, array $options = [], which can be used to pass router-specific options when generating a URI. As an example, the implementation that uses laminas/laminas-router might use these options to pass a translator instance in order to translate a path segment to the currently selected locale.

For consumers, his represents no backwards-incompatible change; consumers may opt-in to the new argument at will. For those implementing the interface, upgrading will require updating your router implementation's signature to match the new interface:

public function generateUri(
    string $name,
    array $substitutions = [],
    array $options = []
) : string

URL helper changes

Mezzio 2.0 uses mezzio/mezzio-helpers version 3.0+. This new version updates the signature of the Mezzio\Helper\UrlHelper from:

function (
    $routeName,
    array $routeParams = []
) : string

to:

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

For consumers, this should represent a widening of features, and will not require any changes, unless you wish to opt-in to the new arguments. See the UrlHelper documentation for information on each argument.

For any users who were extending the class, you will need to update your extension accordingly.

laminas-view renderer changes

Mezzio 2.0 will use mezzio-laminasviewrenderer 1.3+ if that renderer is chosen. Starting with 1.3.0 of that renderer, you may now pass a boolean false value for the layout variable when calling either addDefaultParam() or render() on the renderer instance in order to disable the layout.

Twig renderer changes

Mezzio 2.0 will use mezzio-twigrenderer 1.3+ if that renderer is chosen. Starting with 1.3.0 of that renderer, Twig 2.1+ is now supported.

Adopting a modular architecture

Mezzio 2.0 ships with support for modular architectures from the outset, as detailed in the chapter on modules.

If you wish to update your application to use these features, you will need to install the following packages:

  • laminas/laminas-config-aggregator
  • laminas/laminas-component-installer

As an example:

$ composer require laminas/laminas-config-aggregator \
> laminas/laminas-component-installer

Once installed, you should update your config/config.php file to read as follows:

<?php

use Laminas\ConfigAggregator\ArrayProvider;
use Laminas\ConfigAggregator\ConfigAggregator;
use Laminas\ConfigAggregator\PhpFileProvider;

// To enable or disable caching, set the `ConfigAggregator::ENABLE_CACHE` boolean in
// `config/autoload/local.php`.
$cacheConfig = [
    'config_cache_path' => 'data/config-cache.php',
];

$aggregator = new ConfigAggregator([
    // Include cache configuration
    new ArrayProvider($cacheConfig),

    // Default App module config
    App\ConfigProvider::class,

    // Load application config in a pre-defined order in such a way that local settings
    // overwrite global settings. (Loaded as first to last):
    //   - `global.php`
    //   - `*.global.php`
    //   - `local.php`
    //   - `*.local.php`
    new PhpFileProvider('config/autoload/{{,*.}global,{,*.}local}.php'),

    // Load development config if it exists
    new PhpFileProvider('config/development.config.php'),
], $cacheConfig['config_cache_path']);

return $aggregator->getMergedConfig();

The above should mimic what you already had in place; if it does not, check to see if there are additional paths you were globbing previously.