undefined method `first' on update in rails - ruby-on-rails

Question

I import a csv file into my DB and i have a error when I update it.
My error :
undefined method `first' for nil:NilClass
on line "if agent.update(line)"
My model :
def self.import_agent(file)
fallback = {:counter => 0}
CSV.foreach(file.path, :col_sep => "\t", :headers => true, :quote_char => "\x00", :encoding => 'windows-1251:utf-8') do |row|
line = Hash.new
row.to_hash.each_pair do |k,v|
row ={k.downcase.gsub("agent_", "") => v}
line = line.deep_merge(row)
end
agent = Agent.find_or_initialize_by(code:line["code"])
if agent.update(line)
fallback[:counter] += 1
end
end
return fallback
end
My Controller :
def import_agent
#file = params[:file]
fallback = Import.import_agent(#file)
redirect_to root_path, notice: 'File successfully uploaded, '+fallback[:counter].to_s+' line are added/updated !'
end
Error Log :
Started POST "/import_agent" for 127.0.0.1 at 2015-03-30 11:06:18 +0200
Processing by ImportsController#import_agent as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"pF1GsZ+Z+9tHmiw6k47Y7T7Sjn1ka1bHZqMqwWbBO2QIHBIz2VX9F7kPGP0CyYT6xu3nJnANJdGjDCtE0eISjw==", "file"=>#<ActionDispatch::Http::UploadedFile:0x007ff3d9fccba8 #tempfile=#<Tempfile:/var/folders/xw/pqcy6hjd59x29wf0wqcbhp1h0000gn/T/RackMultipart20150330-7818-f99zac.csv>, #original_filename="EXPORT_AGENT.csv", #content_type="text/csv", #headers="Content-Disposition: form-data; name=\"file\"; filename=\"EXPORT_AGENT.csv\"\r\nContent-Type: text/csv\r\n">, "commit"=>"Import Agent CSV"}
Agent Load (0.3ms) SELECT "agents".* FROM "agents" WHERE "agents"."code" = ? LIMIT 1 [["code", "AG001"]]
(0.1ms) begin transaction
(0.1ms) rollback transaction
Completed 500 Internal Server Error in 62ms
NoMethodError - undefined method `first' for nil:NilClass:
activerecord (4.2.0) lib/active_record/attribute_assignment.rb:114:in `find_parameter_position'
activerecord (4.2.0) lib/active_record/attribute_assignment.rb:103:in `block in extract_callstack_for_multiparameter_attributes'
activerecord (4.2.0) lib/active_record/attribute_assignment.rb:98:in `extract_callstack_for_multiparameter_attributes'
activerecord (4.2.0) lib/active_record/attribute_assignment.rb:76:in `assign_multiparameter_attributes'
activerecord (4.2.0) lib/active_record/attribute_assignment.rb:46:in `assign_attributes'
activerecord (4.2.0) lib/active_record/persistence.rb:249:in `block in update'
activerecord (4.2.0) lib/active_record/transactions.rb:347:in `block in with_transaction_returning_status'
activerecord (4.2.0) lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `block in transaction'
activerecord (4.2.0) lib/active_record/connection_adapters/abstract/transaction.rb:188:in `within_new_transaction'
activerecord (4.2.0) lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `transaction'
activerecord (4.2.0) lib/active_record/transactions.rb:220:in `transaction'
activerecord (4.2.0) lib/active_record/transactions.rb:344:in `with_transaction_returning_status'
activerecord (4.2.0) lib/active_record/persistence.rb:248:in `update'
app/models/import.rb:67:in `block in import_agent'
/Users/gregoryfrerot/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/csv.rb:1739:in `each'
/Users/gregoryfrerot/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/csv.rb:1122:in `block in foreach'
/Users/gregoryfrerot/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/csv.rb:1273:in `open'
/Users/gregoryfrerot/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/csv.rb:1121:in `foreach'
app/models/import.rb:60:in `import_agent'
app/controllers/imports_controller.rb:16:in `import_agent'
actionpack (4.2.0) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (4.2.0) lib/abstract_controller/base.rb:198:in `process_action'
actionpack (4.2.0) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.2.0) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (4.2.0) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `_run_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_process_action_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.0) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (4.2.0) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
activesupport (4.2.0) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.0) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.0) lib/active_support/notifications.rb:164:in `instrument'
actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.2.0) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
activerecord (4.2.0) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.2.0) lib/abstract_controller/base.rb:137:in `process'
actionview (4.2.0) lib/action_view/rendering.rb:30:in `process'
actionpack (4.2.0) lib/action_controller/metal.rb:195:in `dispatch'
actionpack (4.2.0) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.2.0) lib/action_controller/metal.rb:236:in `block in action'
actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:42:in `serve'
actionpack (4.2.0) lib/action_dispatch/journey/router.rb:43:in `block in serve'
actionpack (4.2.0) lib/action_dispatch/journey/router.rb:30:in `serve'
actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:802:in `call'
bullet (4.14.4) lib/bullet/rack.rb:12: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 (1.6.0) lib/rack/etag.rb:24:in `call'
rack (1.6.0) lib/rack/conditionalget.rb:38:in `call'
rack (1.6.0) lib/rack/head.rb:13:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/flash.rb:260:in `call'
rack (1.6.0) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.6.0) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.2.0) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.2.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:647:in `call'
activerecord (4.2.0) lib/active_record/migration.rb:378:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.2.0) lib/active_support/callbacks.rb:88:in `_run_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_call_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
better_errors (2.1.1) lib/better_errors/middleware.rb:84:in `protected_app_call'
better_errors (2.1.1) lib/better_errors/middleware.rb:79:in `better_errors_call'
better_errors (2.1.1) lib/better_errors/middleware.rb:57:in `call'
web-console (2.0.0) lib/action_dispatch/debug_exceptions.rb:18:in `middleware_call'
web-console (2.0.0) lib/action_dispatch/debug_exceptions.rb:13:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.2.0) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.2.0) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.2.0) lib/rails/rack/logger.rb:20:in `call'
quiet_assets (1.1.0) lib/quiet_assets.rb:27:in `call_with_quiet_assets'
actionpack (4.2.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.6.0) lib/rack/methodoverride.rb:22:in `call'
rack (1.6.0) lib/rack/runtime.rb:18:in `call'
activesupport (4.2.0) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
rack (1.6.0) lib/rack/lock.rb:17:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/static.rb:113:in `call'
rack (1.6.0) lib/rack/sendfile.rb:113:in `call'
railties (4.2.0) lib/rails/engine.rb:518:in `call'
railties (4.2.0) lib/rails/application.rb:164:in `call'
rack (1.6.0) lib/rack/content_length.rb:15:in `call'
thin (1.6.3) lib/thin/connection.rb:86:in `block in pre_process'
thin (1.6.3) lib/thin/connection.rb:84:in `pre_process'
thin (1.6.3) lib/thin/connection.rb:53:in `process'
thin (1.6.3) lib/thin/connection.rb:39:in `receive_data'
eventmachine (1.0.5) lib/eventmachine.rb:187:in `run'
thin (1.6.3) lib/thin/backends/base.rb:73:in `start'
thin (1.6.3) lib/thin/server.rb:162:in `start'
rack (1.6.0) lib/rack/handler/thin.rb:19:in `run'
rack (1.6.0) lib/rack/server.rb:286:in `start'
railties (4.2.0) lib/rails/commands/server.rb:80:in `start'
railties (4.2.0) lib/rails/commands/commands_tasks.rb:80:in `block in server'
railties (4.2.0) lib/rails/commands/commands_tasks.rb:75:in `server'
railties (4.2.0) lib/rails/commands/commands_tasks.rb:39:in `run_command!'
railties (4.2.0) lib/rails/commands.rb:17:in `<top (required)>'
bin/rails:4:in `<main>'
Thanks for your help and sorry for my english.

Answer 1

Use find_or_create_by instead of find_or_initialize_by, since the latter does not insert new record into database.