Short guide explaining how to migrate from Silex to Symfony 4+ Flex · Issue #867...

My First Upgrade from Silex 2 to Symfony 4 / Flex

This is just a few notes on the way I approached my first cut-over of a project from Silex to Symfony 4 & Flex. The most important thing I think I would point out for those of us very used to Silex is:

• Rule Translate to Portuguese #1 … Don't fear the change, embrace it!

Stuff might feel "different" or "unnatural" at first, but you quickly adapt and grow attached to the change.

Before you go too far, give this a good read:

• Service container

… don't try to "get" everything now, but having some of it in your mental view will help a lot of this "click" pretty quickly.

Next thing I found valuable was to composer create-project symfony/skeleton && cd skeleton && php -S 127.0.0.1:8000 -t public and have a look at what you've got … a very simple starting point.

Then I did a bunch of composer requires to start adding the external dependencies I knew I was going to require and in a few minutes I had the beginning of what I needed to start porting my Silex project, things like:

• composer.json
  • "require"
  • "require-dev"
  • "config"
  • "scripts"
• symfony.lock
• bin/console
• config/*
• public/index.php
• src/Kernel.php
• .env
• .env.dist

A huge wall you can hit at this point is copying these over, pressing F5 in your browser and watching everything crash.

What I chose to do at this point was to edit my config/services.yaml file and comment out this section:

    App\:
        resource: '../src/*'
        exclude: '../src/{Entity,Migrations,Repository,Tests}'
    App\Controller\:
        resource: '../src/Controller'
        tags: ['controller.service_arguments']

That stopped the DI compiler from scanning every class in src/ and causing a lot of pain trying to port your service classes over.

HUGE NOTE: This approach circumvents a lot of what makes autowiring awesome, you wouldn't normally do this on a new project, but it also allows you to slowly progress though your migration without too much pain.

Important tip, you two best friends at this point in time:

• ./bin/console debug:container
• ./bin/console debug:autowiring

Next, I went through each of my own project's service providers and added the services one by one (as needed) to config/services.yaml

For example, a Twig extension's runtime class:

    App\Twig\Extension\MyRuntime:
        autowire: true
        tags:
            - { name: twig.runtime }

Once you have your base serviced looking like they're wired up, move onto your controllers. I enabled them in my config/services.yaml
one at a time like so:

    App\Controller\MyFirstController:
        tags: ['controller.service_arguments']

The allowed me to step through each one, get it loading and move on. Depending on dependencies you might have to jump through a few iterations of this process.

Depending on the size and complexity of your project, this should get a lot of them close to cut-over. My first one was less than two hours to migrate.