Rails4 fails to save object with has_many-association - ruby-on-rails

Question

Problem solved! It seems that "ChangedAttribute" is not allowed as an association's name.
I'm having an application using Rails with ActiveLdap.
After updating a record in LDAP, I want to add a corresponding EmployeeChange-record in the database. The EmployeeChange-model has a has_many association to the ChangedAttribute-model.
def update
# write changes to LDAP
#employee = Employee.find(params[:id])
#employee.attributes = params[:employee].permit(:sn, :gn, :telephoneNumber, :physicalDeliveryOfficeName)
changes = #employee.changed_attributes
if #employee.save then
#when writing successful
employeeChange = EmployeeChange.new(:employee_cn => #employee.cn, :user_id => current_user.id)
employeeChange.save
end
respond_to do |format|
format.js
end
end
The EmployeeChange-Class
class EmployeeChange < ActiveRecord::Base
has_many :changed_attributes
#ActiveLdap-Connection
def employee
Employee.find(employee_cn)
end
end
The ChangedAttribute-Class
class ChangedAttribute < ActiveRecord::Base
belongs_to :employee_change
end
But when calling employeeChange.save, rails fails with this stacktrace:
Started PATCH "/employees/d1037" for 10.0.2.2 at 2014-01-05 14:35:38 +0100
Processing by EmployeesController#update as JS
Parameters: {"utf8"=>"✓", "employee"=>{"gn"=>"Hannes", "sn"=>"Linsen", "telephoneNumber"=>"T-1337", "physicalDeliveryOffice
Name"=>""}, "id"=>"d1037"}
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 ORDER BY "users"."id" ASC LIMIT 1
LDAP: search_with_limit (0.5ms): {:base=>"ou=Benutzer,dc=foo,dc=bar", :scope=>:sub, :filter=>"(&(cn=d1037)(objectClass=per
son))", :attributes=>["*", "objectClass"], :limit=>1}
LDAP: modify (1.9ms): {:dn=>"cn=d1037,ou=Benutzer,dc=foo,dc=bar", :attributes=>[[:replace, "physicalDeliveryOfficeName", {
"physicalDeliveryOfficeName"=>[]}]]}
(0.1ms) begin transaction
(0.1ms) rollback transaction
Completed 500 Internal Server Error in 63ms
NoMethodError - undefined method `keys' for #<ActiveRecord::Associations::CollectionProxy []>:
activerecord (4.0.2) lib/active_record/relation/delegation.rb:121:in `method_missing'
activerecord (4.0.2) lib/active_record/relation/delegation.rb:68:in `method_missing'
activerecord-deprecated_finders (1.0.3) lib/active_record/deprecated_finders/collection_proxy.rb:22:in `method_missing'
activemodel (4.0.2) lib/active_model/dirty.rb:112:in `changed'
activerecord (4.0.2) lib/active_record/attribute_methods/dirty.rb:84:in `keys_for_partial_write'
activerecord (4.0.2) lib/active_record/attribute_methods/dirty.rb:78:in `create_record'
activerecord (4.0.2) lib/active_record/callbacks.rb:306:in `block in create_record'
activesupport (4.0.2) lib/active_support/callbacks.rb:373:in `_run__4122661215117885092__create__callbacks'
activesupport (4.0.2) lib/active_support/callbacks.rb:80:in `run_callbacks'
activerecord (4.0.2) lib/active_record/callbacks.rb:306:in `create_record'
activerecord (4.0.2) lib/active_record/timestamp.rb:57:in `create_record'
activerecord (4.0.2) lib/active_record/persistence.rb:477:in `create_or_update'
activerecord (4.0.2) lib/active_record/callbacks.rb:302:in `block in create_or_update'
activesupport (4.0.2) lib/active_support/callbacks.rb:383:in `_run__4122661215117885092__save__callbacks'
activesupport (4.0.2) lib/active_support/callbacks.rb:80:in `run_callbacks'
activerecord (4.0.2) lib/active_record/callbacks.rb:302:in `create_or_update'
activerecord (4.0.2) lib/active_record/persistence.rb:106:in `save'
activerecord (4.0.2) lib/active_record/validations.rb:51:in `save'
activerecord (4.0.2) lib/active_record/attribute_methods/dirty.rb:32:in `save'
activerecord (4.0.2) lib/active_record/transactions.rb:270:in `block (2 levels) in save'
activerecord (4.0.2) lib/active_record/transactions.rb:326:in `block in with_transaction_returning_status'
activerecord (4.0.2) lib/active_record/connection_adapters/abstract/database_statements.rb:202:in `block in transaction'
activerecord (4.0.2) lib/active_record/connection_adapters/abstract/database_statements.rb:210:in `within_new_transaction'
activerecord (4.0.2) lib/active_record/connection_adapters/abstract/database_statements.rb:202:in `transaction'
activerecord (4.0.2) lib/active_record/transactions.rb:209:in `transaction'
activerecord (4.0.2) lib/active_record/transactions.rb:323:in `with_transaction_returning_status'
activerecord (4.0.2) lib/active_record/transactions.rb:270:in `block in save'
activerecord (4.0.2) lib/active_record/transactions.rb:281:in `rollback_active_record_state!'
activerecord (4.0.2) lib/active_record/transactions.rb:269:in `save'
app/controllers/employees_controller.rb:28:in `update'
actionpack (4.0.2) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (4.0.2) lib/abstract_controller/base.rb:189:in `process_action'
actionpack (4.0.2) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.0.2) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (4.0.2) lib/active_support/callbacks.rb:423:in `_run__1739796840906245504__process_action__callbacks'
activesupport (4.0.2) lib/active_support/callbacks.rb:80:in `run_callbacks'
actionpack (4.0.2) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (4.0.2) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
activesupport (4.0.2) lib/active_support/notifications.rb:159:in `block in instrument'
activesupport (4.0.2) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.0.2) lib/active_support/notifications.rb:159:in `instrument'
actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.0.2) lib/action_controller/metal/params_wrapper.rb:245:in `process_action'
activerecord (4.0.2) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
activeldap (4.0.1) lib/active_ldap/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.0.2) lib/abstract_controller/base.rb:136:in `process'
actionpack (4.0.2) lib/abstract_controller/rendering.rb:44:in `process'
actionpack (4.0.2) lib/action_controller/metal.rb:195:in `dispatch'
actionpack (4.0.2) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.0.2) lib/action_controller/metal.rb:231:in `block in action'
actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:80:in `dispatch'
actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:48:in `call'
actionpack (4.0.2) lib/action_dispatch/journey/router.rb:71:in `block in call'
actionpack (4.0.2) lib/action_dispatch/journey/router.rb:59:in `call'
actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:680:in `call'
warden (1.2.3) lib/warden/manager.rb:35:in `block in call'
warden (1.2.3) lib/warden/manager.rb:34:in `call'
rack (1.5.2) lib/rack/etag.rb:23:in `call'
rack (1.5.2) lib/rack/conditionalget.rb:35:in `call'
rack (1.5.2) lib/rack/head.rb:11:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/flash.rb:241:in `call'
rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/cookies.rb:486:in `call'
activerecord (4.0.2) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.0.2) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in `call'
activerecord (4.0.2) lib/active_record/migration.rb:369:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.0.2) lib/active_support/callbacks.rb:373:in `_run__4410864778172765141__call__callbacks'
activesupport (4.0.2) lib/active_support/callbacks.rb:80:in `run_callbacks'
actionpack (4.0.2) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/reloader.rb:64:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
better_errors (1.1.0) lib/better_errors/middleware.rb:84:in `protected_app_call'
better_errors (1.1.0) lib/better_errors/middleware.rb:79:in `better_errors_call'
better_errors (1.1.0) lib/better_errors/middleware.rb:56:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.0.2) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.0.2) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:67:in `block in tagged'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:25:in `tagged'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:67:in `tagged'
railties (4.0.2) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
rack (1.5.2) lib/rack/runtime.rb:17:in `call'
activesupport (4.0.2) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/static.rb:64:in `call'
rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
railties (4.0.2) lib/rails/engine.rb:511:in `call'
railties (4.0.2) lib/rails/application.rb:97:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
rack (1.5.2) lib/rack/content_length.rb:14:in `call'
rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
/usr/local/rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/httpserver.rb:138:in `service'
/usr/local/rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/httpserver.rb:94:in `run'
/usr/local/rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/server.rb:295:in `block in start_thread'
Any ideas what the problem might be?
Kind regards,
Tobias

Answer 1

Change
employeeChange = EmployeeChange.new(employee_cn = #employee.cn, user_id = current_user.id)
To
employeeChange = EmployeeChange.new(:employee_cn => #employee.cn, :user_id => current_user.id)