attr_accessible error on rails 4.1.8 upon performing rake db:migrate on heroku

Question

I am still learning Ruby (so I am a complete noob), right now I have my app successfully running locally but when trying to opening the apps on heroku , in which I first perform the heroku run rake db:migrate I stumbled upon a problem.. it tells me :

Running `rake db:migrate` attached to terminal... up, run.2149
-- attr_accessible(:pName, :pQuantity, :pMeter, :pWeight, :pSellPrice,  :pCategory, :pPic)
-- attr_accessible(:pName, :pQuantity, :pMeter, :pWeight, :pSellPrice, :pCategory, :pPic)
rake aborted!
NoMethodError: undefined method `attr_accessible' for #<ActiveRecord::Migration:0x007f2dc2ba45b8>
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:648:in `block in method_missing'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in `block in say_with_time'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in `say_with_time'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:641:in `method_missing'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:406:in `method_missing'
/app/db/migrate/20150802134246_create_inventories.rb:2:in `<class:CreateInventories>'
/app/db/migrate/20150802134246_create_inventories.rb:1:in `<top (required)>'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.8/lib/active_support/dependencies.rb:247:in `require'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.8/lib/active_support/dependencies.rb:247:in `block in require'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.8/lib/active_support/dependencies.rb:232:in `load_dependency'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.1.8/lib/active_support/dependencies.rb:247:in `require'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:761:in `load_migration'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:757:in `migration'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in `disable_ddl_transaction'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:1044:in `use_transaction?'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:954:in `rescue in block in migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:951:in `block in migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in `each'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in `migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:807:in `up'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:785:in `migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.1.8/lib/active_record/railties/databases.rake:34:in `block (2 levels) in <top (required)>'
Tasks: TOP => db:migrate

I have been trying to find out the reason, after wondering around I found out about change in rails 4.0.0 in that attr_accessible are no longer used and we should use strong parameter instead, So removing the attr_accessible from model will solve the problem...

However, I have an empty Model, there is no attr_accessible everywhere i look. (beside this is weird why my apps runs locally but not on heroku?) I can't figured out why this error appear and where to look for solutions.. I have been trying to look at active_record file but am afraid of making any changes, any idea?

also, could anyone tell me any resources that can help me read this type of log errors? I have tried to read some articles but can't find one that is easy to understand for noobs like me... ;(

Answer 1

Glad I could help :)

As far as reading log errors goes, here's what I do. You're going to get a bunch of lines about files you have never touched. That's because although there's most likely an error in something you wrote, the error propagates through the entire Rails framework. That's why Rails is really cool: it does a lot of things for you, so you don't have to worry about them.

If the error is in code you wrote, that file should also be listed in the stack trace. So in this example, you have a bunch of /app/vendor/bundle/... (which I assumed you didn't touch), but then there is an /app/db/migrate/... (which is most likely something you created).

That leads me to think the error is in that file. Plus, it even gives you a line number (that's what the :2 is in create_inventories.rb:2). Granted those line numbers aren't always correct, but it should get you started in the right place!