This document presents a comprehensive overview of Symfony forms, discussing form creation, data handling, validation, event listeners, and best practices. Additionally, it highlights the importance of using objects instead of arrays, demonstrates how to customize forms with event listeners and extensions, and offers guidance on debugging and testing forms. Key topics include form flow, configuration, and the use of data transformers to manage data formats while maintaining data integrity.

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Symfony Form
“Make simple cases simple,
make complex cases possible”
- Bernhard Schussek
presented by Andreii Yatsenko

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About me
● Я Андрюха
● PHP Developer at Oro Inc.
● Live in Kyiv
● Studied at GeekHub ~3 years ago
● 6 years with PHP

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Agenda
● Form Flow
● Form EventListeners
● Form Extensions
● Data Transformers
● Form Tests
● Bad and Good Practices
● Almost W/O code samples

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Form flow
● create form
● set data to form
● handle request
● Profit! do something with updated data
○ E.g. persist data to DB

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How to create form?
At first
● you need to create formFactory
● or if you are using Symfony just get it from
ServiceContainer
$formFactory =
$container->get(“form.factory”);

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How to create form?
● 1) using FormBuilder in Controller :(
$formFactory->createFormBuilder()
->add(‘firstName”)
->add(“lastName”)
->add(“email”);

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How to create form?
● 2) using FormType

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How to create form?
● If you in Controller
$this->createForm($formType)
// or
$this->createFormBuilder()
->add(“name”, “text”)
->getForm();

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How to set form data?

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Always set form data
at form creation!
$data = new User();
$formFactory
->createForm($formType, $data, $options);
// or
$formFactory->createFormBuilder($data);

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Try to not setData
after form creation
Because
● All form events will be triggered twice :(
$form = $formFactory
->createForm($formType);
$form->setData($data);

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Always use objects
instead of arrays!

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If you don’t have object -
you just not created it yet!
● Create DTO

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Why objects,
I like kittens arrays?

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Because of Validation
Validation

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How to Validate Form
● Do not validate form!
● Validate data
○ yaml, xml, annotation drivers for
constrants
● But what if my form doesn’t submit the data?
○ like “Apply terms checkbox”
● Make field mapped = false and validate form

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$formFactory
->createForm($formType, $data, $options);
Form options (configuration)

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Form options (configuration)
● Form options is a form configuration. And
it’s a data too, data that needed for building
and submitting the form, but it’s not the
Form Data (Usually don’t need to be
updated from user input)

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Form options (configuration)
● Buy the way Form Data is an option too. You
can just set $options[‘data’], and form factory
internally use it too. It’s have higher priority
than $data (second param) in
$formFactory
->createForm($type, $data, $options)

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Next
Some form internals

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How form saves your memory
In Symfony2 all form fields are forms too,
and can be reused.
E.x.
● TextFormType
● CategoryFormType
● ProductFormType
● etc.

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How form saves your memory
Form composed from
● Form (form builder template etc.) and
● FormConfig (options with data)
● Form and FormConfig are different
objects.

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How form saves your memory
When you reuse Form, e.x. if you create form
with 20 text fields, only ONE TextForm will be
created.

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How form saves your memory
● But for different fields you have different
data, and usually different options, they
are so called FormConfig and will be
created for each fields, so in our example
you will have 20 FormConfig objects

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How to create form, that
depends on data?
● Use dependency injections:
inject data to FormType container
E.x.
new FormType($someData);

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• How to create form, that
depends on data?
● Use dependency injections:
inject data to FormType container
E.x.
new FormType($someData);

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Never inject dinamic objects
to FormType!

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Never inject dinamic objects
to FormType!
Because you will change FormType,
not the FormConfig, so all forms on page will
be configured the same.

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The right way :)
● Inject to container static objects E.x.
Doctine, not concrete Entities

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If I don’t have static object? :(
● Use custom form options
$formFactory
->createFrom($type, $data, $options);
At first you need to configure them in
FormType::configureOptions()

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But wait, Where to place
dinamic business logic, if I
can’t place it in FormType?
:(

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But wait, Where to place
dinamic business logic, if I
can’t place it in FormType?
In EventListeners! :)

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Form Events
● PRE_SET_DATA
● POST_SET_DATA
● PRE_SUBMIT
● SUBMIT
● POST_SUBMIT

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How to subscribe to form events?
1) Create:
● EventListener - any callable
● EventSubscriber - separate class
implemented
SymfonyComponentEventDispatcherEventSubscriberInterface
2) Add them to FormBuilder
$builder->addEventListener(“PRE_SUBMIT”, $listener);
$builder->addEventSubscriber($subscriber)

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You can even change the form
in EventListeners
● add or remove form fields
http://symfony.
com/doc/current/components/form/form_event
s.html

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You can even change the form
in EventListeners
● but in Symfony you can’t change or
replace form field
In OroPlatform we have FormUtils that solve
this problem
https://github.
com/orocrm/platform/blob/936c1bfcff34c2381a
31fa40726d518d3f6ab0b8/src/Oro/Bundle/For
mBundle/Utils/FormUtils.php

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But you can’t register event
listener like in symfony or
doctrine EventDispatcher,
from another bundle

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How to solve this?

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How to solve this?
FormTypeExtensions

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FormTypeExtensions
● Like form types but have getExtendedType()
method
● extends
SymfonyComponentFormAbstractTypeExtension
● Registered in DI with tag form.type_extension

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How form works with data
internally?

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How form works with data
internally?
E.x. DateTimeFormType
● You set to form timestamp
● User will see human formatted string

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How form works with data
internally?
E.x. DateTimeFormType
● You set to form timestamp
● In EventListeners you work with DateTime
● User will see human formatted string

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How form works with data
internally?
E.x.
● Controller - timestamp
● Form - DateTime
● User - formatted string

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How form works with data
internally?
E.x.
● Model Data - timestamp
● Normalized Data - DateTime
● View Data - formatted string

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Data Transformers
● Model Transformer
● View Transformer
implement
SymfonyComponentFormDataTransformerInterface
2 methods:
● transform($data)
● reverseTransform($data)

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Data Transformers
Register at $builder
$builder
->get('date') ->addModelTransformer
($transformer);

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Data Transformers
● Should only transform data from one
format to another, but never change the
data.
● If you want to change data use
EventListeners

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Debugging Forms

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How to test forms
Unit Test
$builder = $this->createMock(“FormBuilder”);
$builder->expects($this->at(1))
->method(“add”)
->withArguments(“username”, “text”)
//...

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How to test forms
Unit Test
$builder = $this->createMock(“FormBuilder”);
$builder->expects($this->at(1))
->method(“add”)
->withArguments(“username”, “text”)
//...

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How to test forms
● Write Integrational tests
SymfonyComponentFormTestFormIntegrationTestCase
E.x.
https://github.
com/laboro/b2b/blob/9d18a036099357b04d41116ca2dfcaa5
7a59163c/src/OroB2B/Bundle/AccountBundle/Tests/Unit/For
m/Extension/CategoryFormExtensionTest.php#L34-L34

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Agenda
● Form Flow
● Form EventListeners
● Form Extensions
● Data Transformers
● Form Tests

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?