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== session



=== Purpose


The `session` object is an instance of the Servlet API's {jakartaee}jakarta/servlet/http/HttpSession.html[HttpSession] class


=== Examples


[source,groovy]
----
class UserController {

    def logout() {
        log.info "User agent: " + request.getHeader("User-Agent")
        session.invalidate()
        redirect(action: "login")
    }

    def login() {}
}
----


=== Description


The {jakartaee}jakarta/servlet/http/HttpSession.html[HttpSession] class is useful for associated session data with a client.

Session attributes which are normally accessible from the {jakartaee}jakarta/servlet/http/HttpSession.html#getAttribute(java/lang/String)[getAttribute] can also be indexed into using the array index operator or de-reference operator:

[source,groovy]
----
def user = session["user"]

session["user"] = "John"

assert "John" == session.user
----
