Controller Flashcards
What are controllers in general?
- usually methods in a controller-class
- reading a request and returning a response
What can the response contain for example?
HTML page, JSON, XML, a file download, a redirect, a 404 error (or anything else)
Why the AbstractController?
Contains a few http-related helpers like ->createNotFoundException() or ->generateUrl()
Which methods are used to redirect?
- redirectToRoute()
- redirect()
Which method is used to create a Response from a template?
- render()
Which naming convention applies to Controllers?
It should contain the “Controller”-suffix
What happens if Exceptions, which are no instance of HttpException are being thrown?
Symfony will turn it into a 500
How to access the HttpRequest?
Through an argument in the controller-method
What are possibilities to map query-parameters to php values?
- # [MapQueryParameter] (To map separate query parameters to values)
- # [MapQueryString] (To map the all query parameters to an object)
What is the default http response code if a validation for #[MapQueryString] fails?
404
How can the default http response code for failing request-validations be overwritten?
with the argument “validationFailedStatusCode”
How can you return a fallback DTO with #[MapQueryString] in case no query-parameters exist?
As default parameter-value:
~~~
#[MapQueryString] UserDto $userDto = new UserDto()
~~~
What is the default http response code if a validation for #[MapRequestPayload] fails?
422
Which Response-Type is used to return a file for a download?
BinaryFileResponse
How can you return a file for a download inside a controller?
use Symfony\Component\HttpFoundation\File\File; return $this->file(new File(), 'filename.txt')
What are early hints?
Early hints tell the browser to start downloading some assets even before the application sends the response content (Most of the time css or javascript)
How do you retrieve cookies from a request?
$request->cookies->get('PHPSESSID');Where does symfony pass the Request-Object?
To any controller that has a parameter typehinted with “Request”
How do you define a Controller-Route in a yaml config?
api_post_edit:
path: /api/posts/{id}
controller: App\Controller\BlogApiController::edit
methods: PUTHow can conditions be checked in route configurations?
post_show:
path: /posts/{id}
controller: 'App\Controller\DefaultController::showPost'
# expressions can retrieve route parameter values using the "params" variable
condition: "params['id'] < 1000"How can you display the flash messages from a session via twig?
{% for message in app.flashes('notice') %}
<div class="flash-notice">
{{ message }}
</div>
{% endfor %}
or, if all of them should be rendered in one place
~~~
{% for label, messages in app.flashes %}
{% for message in messages %}
<div class="flash-{{ label }}">
{{ message }}
</div>
{% endfor %}
{% endfor %}
~~~
How can a flashbag-message be selected without removing it from the stack?
with the method peek();
How can a flashbag-message be selected and automatically be removed from the stack?
with the method get();
How can the default ErrorController be overridden?
By configuration:
~~~
# config/packages/framework.yaml
framework:
error_controller: App\Controller\ErrorController::show
~~~
Which information does the TwigErrorRenderer to the twig-template?
- status_code
- status_text
Additionally the whole HttpException-Object. Can be used like:
{{ exception.message }}
How can the extension be guessed according to the mimtype of a file?
$uploadedFile->guessExtension();
What does the method
$uploadedFile->getClientOriginalPath()return in case the user uploaded a directory?
The webkitRelativePath provided by the browser
Why should the FileType in symfony-forms always use “unmapped”?
Because not the image itself, but the filename is being attached to this form field. Therefore, in the controller the image must be read and handled via the the name manually:
$request->get('foo')->getData();
In this example, ‘foo’ is the name of the field in the symfony-form.
How can static templates be rendered directly without controller logic?
via routes-config
acme_privacy:
path: /privacy
controller: Symfony\Bundle\FrameworkBundle\Controller\TemplateController
defaults:
template: 'static/privacy.html.twig'
statusCode: 200
How to Redirect to Urls and Routes directly from a route?
via routes-config
~~~
doc_shortcut:
path: /doc
controller: Symfony\Bundle\FrameworkBundle\Controller\RedirectController
defaults:
route: ‘doc_page’
~~~
How to keep query params when redirecting directly via routes-config?
keepQueryParams: true
What are TargetedValueResolvers used for?
To use a specific value resolver ONLY when being added explicitely. Not in the default resolver-chain e.g.:
#[AsTargetedValueResolver('booking_id')]
class BookingIdValueResolver implements ValueResolverInterface
#[Route('/booking/{id}')]
public function show(
#[ValueResolver('booking_id')]
Booking $booking
): Response
Whats the purpose of ValueResolvers?
Use specific business-logic to map a parameter to some specific type. E.g: EntityId -> Entity
What does the BackedEnumValueResolver do?
Convert a param with primitive type to the typehinted enum
What does the RequestPayloadValueResolver do?
Maps the request payload or the query string into the type-hinted object
- MapQueryString
- MapRequestPayload
RequestAttributeValueResolver
Attempts to find a request attribute that matches the name of the argument
DateTimeValueResolver
Attempts to find a request attribute that matches the name of the argument and injects a DateTimeInterface object if type-hinted with a class extending DateTimeInterface.
By default any input that can be parsed as a date string by PHP is accepted.
What does the MapDateTime do?
It uses a date-format and a value resolver to resolve the given date string to an object of DateTimeInterface
What does the RequestValueResolver do?
Injects the current Request if type-hinted with Request or a class extending Request.
Often used in controllers.
What does the ServiceValueResolver do?
Injects a service if type-hinted with a valid service class or interface. This works like autowiring.
What does the SessionValueResolver do?
Injects the configured session class implementing SessionInterface if type-hinted with SessionInterface or a class implementing SessionInterface.
What does the DefaultValueResolver do?
Will set the default value of the argument if present and the argument is optional.
What does the UuidValueResolver do?
Attempts to convert any UID values from a route path parameter into UID objects. Leads to a 404 Not Found response if the value isn’t a valid UID.
What does the UserValueResolver do?
Injects the object that represents the current logged in user if type-hinted with UserInterface. #[CurrentUser] attribute can be used to map to a specific user class to the argument.
What does the SecurityTokenValueResolver do? And what happens if the value is typehinten non-nullable and no token exists?
Injects the object that represents the current logged in token if type-hinted with TokenInterface or a class extending it.
If the argument is not nullable and there is no logged in token, an HttpException with status code 401 is thrown by the resolver to prevent access to the controller.
What does the EntityValueResolver do?
Automatically query for an entity and pass it as an argument to your controller. E.g. via ID
What does the ValueResolver do?
It can take a specific ValueResolver-class as an argument and directly uses this. Therefore its some kind of targeted and can improve performance, since other valueResolvers wont be called before.
How does symfony manage the order of the ValueResolvers being called?
With a hard defined priority for each resolver
Which interface needs to be implemented to define an own value resolver?
ValueResolverInterface
