Controller

Question 1

What are controllers in general?

Answer 1

• usually methods in a controller-class
• reading a request and returning a response

Question 2

What can the response contain for example?

Answer 2

HTML page, JSON, XML, a file download, a redirect, a 404 error (or anything else)

Question 3

Why the AbstractController?

Answer 3

Contains a few http-related helpers like ->createNotFoundException() or ->generateUrl()

Question 4

Which methods are used to redirect?

Answer 4

• redirectToRoute()
• redirect()

Question 5

Which method is used to create a Response from a template?

Answer 5

• render()

Question 6

Which naming convention applies to Controllers?

Answer 6

It should contain the “Controller”-suffix

Question 7

What happens if Exceptions, which are no instance of HttpException are being thrown?

Answer 7

Symfony will turn it into a 500

Question 8

How to access the HttpRequest?

Answer 8

Through an argument in the controller-method

Question 9

What are possibilities to map query-parameters to php values?

Answer 9

• # [MapQueryParameter] (To map separate query parameters to values)
• # [MapQueryString] (To map the all query parameters to an object)

Question 10

What is the default http response code if a validation for #[MapQueryString] fails?

Answer 10

404

Question 11

How can the default http response code for failing request-validations be overwritten?

Answer 11

with the argument “validationFailedStatusCode”

Question 12

How can you return a fallback DTO with #[MapQueryString] in case no query-parameters exist?

Answer 12

As default parameter-value:

#[MapQueryString] UserDto $userDto = new UserDto()

Question 13

What is the default http response code if a validation for #[MapRequestPayload] fails?

Answer 13

422

Question 14

Which Response-Type is used to return a file for a download?

Answer 14

BinaryFileResponse

Question 15

How can you return a file for a download inside a controller?

Answer 15

use Symfony\Component\HttpFoundation\File\File;

return $this->file(new File(), 'filename.txt')

Question 16

What are early hints?

Answer 16

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)

Question 17

How do you retrieve cookies from a request?

Answer 17

$request->cookies->get('PHPSESSID');

Question 18

Where does symfony pass the Request-Object?

Answer 18

To any controller that has a parameter typehinted with “Request”

Question 19

How do you define a Controller-Route in a yaml config?

Answer 19

api_post_edit:
    path:       /api/posts/{id}
    controller: App\Controller\BlogApiController::edit
    methods:    PUT

Question 20

How can conditions be checked in route configurations?

Answer 20

post_show:
    path:       /posts/{id}
    controller: 'App\Controller\DefaultController::showPost'
    # expressions can retrieve route parameter values using the "params" variable
    condition:  "params['id'] < 1000"

Question 21

How can you display the flash messages from a session via twig?

Answer 21

{% 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 %}
~~~

Question 22

How can a flashbag-message be selected without removing it from the stack?

Answer 22

with the method peek();

Question 23

How can a flashbag-message be selected and automatically be removed from the stack?

Answer 23

with the method get();

Question 24

How can the default ErrorController be overridden?

Answer 24

By configuration:

# config/packages/framework.yaml
framework:
    error_controller: App\Controller\ErrorController::show

Question 25

Which information does the TwigErrorRenderer to the twig-template?

Answer 25

- status_code - status_text Additionally the whole HttpException-Object. Can be used like: ```{{ exception.message }} ```

Question 26

How can the extension be guessed according to the mimtype of a file?

Answer 26

```$uploadedFile->guessExtension();```

Question 27

What does the method ```$uploadedFile->getClientOriginalPath()``` return in case the user uploaded a directory?

Answer 27

The webkitRelativePath provided by the browser

Question 28

Why should the FileType in symfony-forms always use "unmapped"?

Answer 28

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.

Question 29

How can static templates be rendered directly without controller logic?

Answer 29

via routes-config ``` acme_privacy: path: /privacy controller: Symfony\Bundle\FrameworkBundle\Controller\TemplateController defaults: template: 'static/privacy.html.twig' statusCode: 200 ```

Question 30

How to Redirect to Urls and Routes directly from a route?

Answer 30

via routes-config ``` doc_shortcut: path: /doc controller: Symfony\Bundle\FrameworkBundle\Controller\RedirectController defaults: route: 'doc_page' ```

Question 31

How to keep query params when redirecting directly via routes-config?

Answer 31

keepQueryParams: true

Question 32

What are TargetedValueResolvers used for?

Answer 32

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```

Question 33

Whats the purpose of ValueResolvers?

Answer 33

Use specific business-logic to map a parameter to some specific type. E.g: EntityId -> Entity

Question 34

What does the BackedEnumValueResolver do?

Answer 34

Convert a param with primitive type to the typehinted enum

Question 35

What does the RequestPayloadValueResolver do?

Answer 35

Maps the request payload or the query string into the type-hinted object - MapQueryString - MapRequestPayload

Question 36

RequestAttributeValueResolver

Answer 36

Attempts to find a request attribute that matches the name of the argument

Question 37

DateTimeValueResolver

Answer 37

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.

Question 38

What does the MapDateTime do?

Answer 38

It uses a date-format and a value resolver to resolve the given date string to an object of DateTimeInterface

Question 39

What does the RequestValueResolver do?

Answer 39

Injects the current Request if type-hinted with Request or a class extending Request. Often used in controllers.

Question 40

What does the ServiceValueResolver do?

Answer 40

Injects a service if type-hinted with a valid service class or interface. This works like autowiring.

Question 41

What does the SessionValueResolver do?

Answer 41

Injects the configured session class implementing SessionInterface if type-hinted with SessionInterface or a class implementing SessionInterface.

Question 42

What does the DefaultValueResolver do?

Answer 42

Will set the default value of the argument if present and the argument is optional.

Question 43

What does the UuidValueResolver do?

Answer 43

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.

Question 44

What does the UserValueResolver do?

Answer 44

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.

Question 45

What does the SecurityTokenValueResolver do? And what happens if the value is typehinten non-nullable and no token exists?

Answer 45

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.

Question 46

What does the EntityValueResolver do?

Answer 46

Automatically query for an entity and pass it as an argument to your controller. E.g. via ID

Question 47

What does the ValueResolver do?

Answer 47

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.

Question 48

How does symfony manage the order of the ValueResolvers being called?

Answer 48

With a hard defined priority for each resolver

Question 49

Which interface needs to be implemented to define an own value resolver?

Answer 49

ValueResolverInterface