Route: role put Action, error parameters

I have this rule in my route:
$routes->put('api/user/( : segment)', 'Api\User\User::update/$1');
In the controller i have:
print_r($this->request->getRawInput());
the printout that comes out is this:
Array
(
    [----------------------------691194008045713214555940
Content-Disposition:_form-data;_name] => "stato_user"

2
----------------------------691194008045713214555940--

)


how can i recover the "user_state2 parameter?
Use PostMan
Thanks

You need to parse data. CodeIgniter does not support multipart/form-data.