Takeaways from SymfonyLive Online German Edition 2021

Software Developer & DevOps Engineer writing about stuff I encounter during my daily work.

Boring is the new hype

Context is important. What might be the best solution for big companies like Netflix, Stripe, etc. is not necessarily for your use-case / situation

Adding new tools to the toolbelt has a cost (build up knowledge, how to test, infrastructure, maintenance, deployment, CI integration, ...). Think about if the problem you are facing can be solved by tools you already have. If you already have a tool that provides a Good enough solution, ask yourself, is it worth using a "fancy new tool" for it?

Learning new technologies is fun. But you are probably doing a bad job (at first at least), and creating technical debt or a suboptimal solution. Is it worth maintaing that technology in the long run?

Symfony is a boring technology. Strict BC policy. Stable foundation: HTTP, Console, ...

Fabien would recommend PostgresSQL over MySQL

It acually supports Async Messages (LISTEN/NOTIFY feature). Can be used instead of something like RabbitMQ
- => One less piece of infrastructure to manage
Also supports Locks (Advisory locks). Do you really need Redis for that? Or is Postgres good enough for your use case?
- => One less piece of infrastructure to manage

Boring is about making safe choices

Easy to find support
Easier to hire people with knowledge

Boring Infrastructure

Do you build everything yourself? Or use SaaS instead?
- SaaS helps you focus on the topics that provide real business value

Does not recommend using LTS Symfony version

Recommendation: Upgrade every 6 months

Fabien's ideal stack

Currently not: Microservices on a K8s Cluster. Too complex to manage the infrastructure. Most users probably don't really have the needs for it
A VM on a PaaS
A Managed PostgreSQL DB
A CDN
- Improves uptime. Probably adds a .9%
- Uses standard HTTP headers
- Fabien likes to use Cloudflare (I do as well)
A bunch of SaaS tools

If your're interested in the topic. I'd also recommend Dan McKinley's Blog Post and Presentation about the topic.

Symfony Notifier Demystified

Provides functionality to send notifications to recipient

The following channels are available. These each support multiple Transports (except Browser)

Email
SMS
- Twilio
- Nexmo
- Smsapi
- ...
Chat
- Slack
- Telegram
- Discord
- LinkedIn
- Google Chat
- ...
Browser
- Sends flash messages

Notifications can implement a getChannel() method. Which defines which channel it should be sent to.

Notifications have an importance. This can be used to select which Notification should be sent to which channel. getChannel() overrides this if set

Channels create a channel-specific message (e.g. SmsMessage, EmailMessage) from the given Notification

Channels provide interfaces (e.g. ChatNotificationInterface), which contain a for example a asChatMessage() method in the Chat Channel case: Notification is able to define how a message is created

Channels each have their own Composer package

It also provides a Monolog handler. Allows sending Monolog logs to the Notifier which can for example send a Slack message

Example use cases: Support requests with different possible priorities

You can find more about the Notifier Component in the Symfony Docs for it.

Hidden gems in Symfony

App\Kernel - A full app in a single file

Can subscribe to events
Can declare inline services by using configureContainer()
Allows using #Route annotations
Use cases
- Useful in testing
- Very small Microservice
- Lambda function

Named Autowiring Aliases

Combine type and parameter name
- 'Symfony\Contracts\CacheInterface $arrayCache': @my_array_cache

Service Locators and Iterators

AsTaggedItem

Command Definition

public static $defaultDescription
#[AsCommand(name: '', description: '')]

Env Var Processors

require
trim
default
url
EnvVarLoaderInterface
- Allows you to implement your own implementation of a environment variable provider
- Is called on every request
- Example use case: High availability setup. A database instance goes down. Instantly remove it from the DB settings to route DB traffic away from the failed instance

Process

Wait until callback feature: ->waitUntil() method
- Allows making it event driven
Supports "prepared" command lines
- E.g. Process::fromShellCommandLine(ls -ls "{:$path}")
- Protection against command injection (similar to SQL injection)

VarDumper

To dump in JSON api and not break the JSON: Use server dumper

HttpClient

Async HTTPlug client
- Uses proxies
AsyncDecoratorTrait
- Allows processing responses without breaking async

Routing

Allow inline definition of requirements & defaults inside Annotation
stateless Attribute. Provides error if the session is used

Validator

NotCompromisedPassword validator
NotCompromisedPassword Annotation
Doctrine #EnableAutoMapping Annotation to fail validation if Doctrine constraints are violated

VarExporter

Faster than unserialize()

Schrödinger's SQL - The SQL inside the Doctrine box

Unit Of Work

Entity Manager caches Entities. To be able to get the updated version of it, entities have to be cleared from the Entity Manager using ->clear()

Performance

Lazy Loading
- Suboptimal performance in some use-cases.
- For example: Load entities with an array field that references another table/entity type (let's say Foo). Loop over these loaded entities and call getFoo(). Each foreach iteration will cause a separate SQL query. Not optimal
Eager Loading
- Might hydrate entities with data that is never used. Also suboptimal
Takeaways
- Be aware of the SQL that Doctrine executes under the hood

Using Doctrine does not prevent you from using plain SQL instead of DQL, where it makes sense. E.g. Window Functions, Value Lists, JSON_OBJECT()

What's new in Doctrine 2021?

DBAL 3

Statement & Result are now separated
- Statement: For executing the statement
- Result: For fetching query results
Fetch API overhauled
- More specific fetch methods replace the existing ones
- They now return a Result object
executeStatement() replaces executeUpdate(), exec() & query(). Returns count of changed rows.
Doctrine now does automatic reconnects. Automatically reconnects when DB is available again. Helps with long running tasks. ping() & reconnect() is not necessary anymore.
DBALException replaced by Exception
DBAL 2 is forward compatible to DBAL 3. You can already use the APIs from DBAL 3 in DBAL 2.

ORM

PHP 8 attributes are supported
Typed Property Defaults: Doctrine uses PHP types by default, if defined
- Array => JSON
- Int => Int
- ...
Support for static analyser (PHPStan, Psalm) typed arrays
toIterable() method

Roadmap

Switch caching layer to PSR-6 caching
Better Value Object DQL support
Value Objects via nested JSON
Enums
ManyToAny Associations
Dynamic Column Mapping
Better Transaction/Unit Of Work

PHP 8

Symfony 6 will require PHP 8

Useful new features

get_debug_type()
str_starts_with(), str_ends_with(), str_contains()
Constructor Property Promotion
throw is now an expression. Allows using throw in arrow functions, after ?? or ?:, ...
- => Less noisy error handling code
Nullsafe operator for method calls ?->
match() expression. Can be used instead of switch statements
Named arguments
Enums (PHP 8.1)

Takeaways from SymfonyLive Online German Edition 2021

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Boring is the new hype

Symfony Notifier Demystified

Hidden gems in Symfony

Schrödinger's SQL - The SQL inside the Doctrine box

What's new in Doctrine 2021?

PHP 8

The New Testing Landscape: Panther, Foundry & More