Topic: How generate a request to test controller with data from two models

I am passing a model with its id and another model again with its id:

{"commit"=>"Associate", "authenticity_token"=>"...", "action"=>"associate", "id"=>"38", "geo_physical"=>{"id"=>"6"}, "controller"=>"organisations"}

I am trying to send a proper request to the controller with this:

post :associate, :organisation => {:id => "11"}, :geo_physical => {:id => "11"}

With rspec I get:

ActionController::RoutingError in 'OrganisationsController POST associate with valid params assigns a newly created org. as @organisation'
No route matches {:organisation=>{:id=>"11"}, :controller=>"organisations", :geo_physical=>{:id=>"11"}, :action=>"associate"}