rails question find no result

Question

Hey.Guys! Now .I have a question ,i want someone to help me to solve it ,the log of the problem like the under text

>> Department.find(EmeReference.find(:all,:select =>:ref_config_id,:conditions=>"emergency_id = 1"))
ActiveRecord::RecordNotFound: Couldn't find Department with ID=0
 from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/base.rb:1591:in `find_one'
 from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/base.rb:1574:in `find_from_ids_without_cache'
 from (__DELEGATION__):2:in `__send__'
 from (__DELEGATION__):2:in `find_from_ids_without_cache'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/query/abstract.rb:158:in `find_from_keys'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/query/primary_key.rb:31:in `miss'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/query/abstract.rb:66:in `hit_or_miss'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/accessor.rb:17:in `call'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/accessor.rb:17:in `fetch'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/accessor.rb:29:in `get'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/query/abstract.rb:65:in `hit_or_miss'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/query/abstract.rb:18:in `perform'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/query/primary_key.rb:17:in `perform'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/query/abstract.rb:7:in `perform'
 from /usr/lib/ruby/gems/1.8/gems/nkallen-cache-money-0.2.5/lib/cash/finders.rb:29:in `find_from_ids'
 from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/base.rb:616:in `find'
 from (irb):135

that's the question! Thank you and best regards!

Answer 1

Rails manages relations between models by itself. You do not need to nest calls like that.

EmeReference.find_by_emergency_id(1).department

This will retrieve the EmeReference object with emergency_id=1. And as you should have defined a relation between that model and the Department one, rails creates a virtual method of this second model name, allowing you to get it.

You should look at those two guides. Active Record Associations and Active Record Query Interface