I can't search using taxonomies anywhere except hosts (which have belongs_to instead of has_many relation). This is blocker for #812.

To reproduce, go to e.g. subnets page and try to find subnets from specific organization like this
"organization = RedHat"

you'll receive

NoMethodError in SubnetsController#index

undefined method `klass' for nil:NilClass

app/controllers/subnets_controller.rb:5:in `index'
app/models/concerns/foreman/thread_session.rb:33:in `clear_thread'
lib/middleware/catch_json_parse_errors.rb:9:in `call'

Parameters:

{"utf8"=>"✓",
 "search"=>"organization = RedHat",
 "locale"=>nil}