[[mvc-ann-sessionattributes]]
= `@SessionAttributes`

[.small]#xref:web/webflux/controller/ann-methods/sessionattributes.adoc[See equivalent in the Reactive stack]#

`@SessionAttributes` is used to store model attributes in the HTTP Servlet session between
requests. It is a type-level annotation that declares the session attributes used by a
specific controller. This typically lists the names of model attributes or types of
model attributes that should be transparently stored in the session for subsequent
requests to access.

The following example uses the `@SessionAttributes` annotation:

[tabs]
======
Java::
+
[source,java,indent=0,subs="verbatim,quotes"]
----
	@Controller
	@SessionAttributes("pet") // <1>
	public class EditPetForm {
		// ...
	}
----
<1> Using the `@SessionAttributes` annotation.

Kotlin::
+
[source,kotlin,indent=0,subs="verbatim,quotes"]
----
	@Controller
	@SessionAttributes("pet") // <1>
	class EditPetForm {
		// ...
	}
----
<1> Using the `@SessionAttributes` annotation.
======

On the first request, when a model attribute with the name, `pet`, is added to the model,
it is automatically promoted to and saved in the HTTP Servlet session. It remains there
until another controller method uses a `SessionStatus` method argument to clear the
storage, as the following example shows:

[tabs]
======
Java::
+
[source,java,indent=0,subs="verbatim,quotes"]
----
	@Controller
	@SessionAttributes("pet") // <1>
	public class EditPetForm {

		// ...

		@PostMapping("/pets/{id}")
		public String handle(Pet pet, BindingResult errors, SessionStatus status) {
			if (errors.hasErrors) {
				// ...
			}
			status.setComplete(); // <2>
			// ...
		}
	}
----
<1> Storing the `Pet` value in the Servlet session.
<2> Clearing the `Pet` value from the Servlet session.

Kotlin::
+
[source,kotlin,indent=0,subs="verbatim,quotes"]
----
@Controller
@SessionAttributes("pet") // <1>
class EditPetForm {

	// ...

	@PostMapping("/pets/{id}")
	fun handle(pet: Pet, errors: BindingResult, status: SessionStatus): String {
		if (errors.hasErrors()) {
			// ...
		}
		status.setComplete() // <2>
		// ...
	}
}
----
<1> Storing the `Pet` value in the Servlet session.
<2> Clearing the `Pet` value from the Servlet session.
======


