# Operations
API Platform Core relies on the concept of operations. Operations can be applied to a resource exposed by the API. From
an implementation point of view, an operation is a link between a resource, a route and its related controller.
Watch the Operations screencast
API Platform automatically registers typical [CRUD](https://en.wikipedia.org/wiki/Create,_read,_update_and_delete) operations
and describes them in the exposed documentation (Hydra and Swagger). It also creates and registers routes corresponding
to these operations in the Symfony routing system (if it is available).
The behavior of built-in operations is briefly presented in the [Getting started](getting-started.md#mapping-the-entities)
guide.
The list of enabled operations can be configured on a per-resource basis. Creating custom operations on specific routes
is also possible.
There are two types of operations: collection operations and item operations.
Collection operations act on a collection of resources. By default two routes are implemented: `POST` and `GET`. Item
operations act on an individual resource. Three default routes are defined: `GET`, `PUT` and `DELETE` (`PATCH` is also supported
when [using the JSON:API format](content-negotiation.md), as required by the specification).
When the `ApiPlatform\Core\Annotation\ApiResource` annotation is applied to an entity class, the following built-in CRUD
operations are automatically enabled:
Collection operations:
Method | Mandatory | Description
-------|-----------|------------------------------------------
`GET` | yes | Retrieve the (paginated) list of elements
`POST` | no | Create a new element
Item operations:
Method | Mandatory | Description
---------|-----------|-------------------------------------------
`GET` | yes | Retrieve an element
`PUT` | no | Replace an element
`PATCH` | no | Apply a partial modification to an element
`DELETE` | no | Delete an element
Note: the `PATCH` method must be enabled explicitly in the configuration, refer to the [Content Negotiation](content-negotiation.md) section for more information.
Note: with JSON Merge Patch, the [null values will be skipped](https://symfony.com/doc/current/components/serializer.html#skipping-null-values) in the response.
Note: Current `PUT` implementation behaves more or less like the `PATCH` method.
Existing properties not included in the payload are **not** removed, their current values are preserved.
To remove an existing property, its value must be explicitly set to `null`.
Implementing [the standard `PUT` behavior](https://httpwg.org/specs/rfc7231.html#PUT) is on the roadmap, follow [issue #4344](https://github.com/api-platform/core/issues/4344) to track the progress.
## Enabling and Disabling Operations
If no operation is specified, all default CRUD operations are automatically registered. It is also possible - and recommended
for large projects - to define operations explicitly.
Keep in mind that `collectionOperations` and `itemOperations` behave independently. For instance, if you don't explicitly
configure operations for `collectionOperations`, `GET` and `POST` operations will be automatically registered, even if you
explicitly configure `itemOperations`. The reverse is also true.
Operations can be configured using annotations, XML or YAML. In the following examples, we enable only the built-in operation
for the `GET` method for both `collectionOperations` and `itemOperations` to create a readonly endpoint.
`itemOperations` and `collectionOperations` are arrays containing a list of operations. Each operation is defined by a key
corresponding to the name of the operation that can be anything you want and an array of properties as value. If an
empty list of operations is provided, all operations are disabled.
If the operation's name matches a supported HTTP methods (`GET`, `POST`, `PUT`, `PATCH` or `DELETE`), the corresponding `method` property
will be automatically added.
```php
```
The previous example can also be written with an explicit method definition:
```php
['method' => 'get'],
],
itemOperations: [
'get' => ['method' => 'get'],
],
)]
class Book
{
// ...
}
```
```yaml
# api/config/api_platform/resources.yaml
App\Entity\Book:
collectionOperations:
get:
method: GET
itemOperations:
get:
method: GET
```
```xml
GET
```
API Platform Core is smart enough to automatically register the applicable Symfony route referencing a built-in CRUD action
just by specifying the method name as key, or by checking the explicitly configured HTTP method.
If you do not want to allow access to the resource item (i.e. you don't want a `GET` item operation), instead of omitting it altogether, you should instead declare a `GET` item operation which returns HTTP 404 (Not Found), so that the resource item can still be identified by an IRI. For example:
```php
['method' => 'get'],
],
itemOperations: [
'get' => [
'controller' => NotFoundAction::class,
'read' => false,
'output' => false,
],
],
)]
class Book
{
}
```
```yaml
# api/config/api_platform/resources.yaml
App\Entity\Book:
collectionOperations:
get: ~
itemOperations:
get:
controller: ApiPlatform\Core\Action\NotFoundAction
read: false
output: false
```
```xml
ApiPlatform\Core\Action\NotFoundAction
false
false
```
## Configuring Operations
The URL, the method and the default status code (among other options) can be configured per operation.
In the next example, both `GET` and `POST` operations are registered with custom URLs. Those will override the URLs generated by default.
In addition to that, we require the `id` parameter in the URL of the `GET` operation to be an integer, and we configure the status code generated after successful `POST` request to be `301`:
```php
[
'path' => '/grimoire',
'status' => 301,
],
],
itemOperations: [
'get' => [
'path' => '/grimoire/{id}',
'requirements' => ['id' => '\d+'],
'defaults' => ['color' => 'brown'],
'options' => ['my_option' => 'my_option_value'],
'schemes' => ['https'],
'host' => '{subdomain}.api-platform.com',
],
],
)]
class Book
{
//...
}
```
```yaml
# api/config/api_platform/resources.yaml
App\Entity\Book:
collectionOperations:
post:
path: '/grimoire'
status: 301
itemOperations:
get:
method: 'GET'
path: '/grimoire/{id}'
requirements:
id: '\d+'
defaults:
color: 'brown'
host: '{subdomain}.api-platform.com'
schemes: ['https']
options:
my_option: 'my_option_value'
```
```xml
/grimoire
301
/grimoire/{id}
\d+
brown
{subdomain}.api-platform.com
https
brown
```
In all these examples, the `method` attribute is omitted because it matches the operation name.
When specifying sub options, you must always use snake case as demonstrated below with the `denormalization_context` option on the `put` operation:
```php
[
'denormalization_context' => [
'groups' => ['item:put'],
'swagger_definition_name' => 'put',
],
],
'delete',
],
],
denormalizationContext: [
'groups' => ['item:post'],
'swagger_definition_name' => 'post',
],
)]
class Book
{
//...
}
```
```yaml
# api/config/api_platform/resources.yaml
App\Entity\Book:
itemOperations:
get: ~
put:
denormalization_context:
groups: ['item:put']
swagger_definition_name: 'put',
delete: ~
denormalizationContext:
groups: ['item:post']
swagger_definition_name: 'post'
```
```xml
item:put
put
item:post
post
```
## Prefixing All Routes of All Operations
Sometimes it's also useful to put a whole resource into its own "namespace" regarding the URI. Let's say you want to
put everything that's related to a `Book` into the `library` so that URIs become `library/book/{id}`. In that case
you don't need to override all the operations to set the path but configure the `route_prefix` attribute for the whole entity instead:
```php
/library
```
Alternatively, the more verbose attribute syntax can be used: `#[ApiResource(attributes: ["route_prefix" => "/library"])]`.
## Expose a Model Without Any Routes
Sometimes, you may want to expose a model, but want it to be used through subrequests only, and never through item or collection operations.
Because the OpenAPI standard requires at least one route to be exposed to make your models consumable, let's see how you can manage this kind
of issue.
Let's say you have the following entities in your project:
```php
[
'method' => 'GET',
'path' => '/places/{id}/weather',
'controller' => GetWeather::class,
],
],
)]
class Place
{
// ...
```
The `GetWeather` controller fetches the weather for the given city and returns an instance of the `Weather` entity.
This implies that API Platform has to know about this entity, so we will need to make it an API resource too:
```php
[
'method' => 'GET',
'controller' => SomeRandomController::class,
],
],
)]
class Weather
{
// ...
```
This way, we expose a route that will do… nothing. Note that the controller does not even need to exist.
It's almost done, we have just one final issue: our fake item operation is visible in the API docs.
To remove it, we will need to [decorate the Swagger documentation](openapi.md#overriding-the-openapi-specification).
Then, remove the route from the decorator:
```php
decorated = $decorated;
}
public function __invoke(array $context = []): OpenApi
{
$openApi = $this->decorated->__invoke($context);
$paths = $openApi->getPaths()->getPaths();
$filteredPaths = new Model\Paths();
foreach ($paths as $path => $pathItem) {
// If a prefix is configured on API Platform's routes, it must appear here.
if ($path === '/weathers/{id}') {
continue;
}
$filteredPaths->addPath($path, $pathItem);
}
return $openApi->withPaths($filteredPaths);
}
}
```
That's it: your route is gone!