ActiveRecord doesn't work on one table

问题

I have a Rails Model:

ruby-1.9.2-p0 > NavItem
 => NavItem(id: integer, item_identifier: string, description: string, description2: string, packing_unit: string, sales_unit_of_measure: string, ean_code: string, evp_price: string, item_category_code: string, class: string, product_group_code: string, maintenance_status: string)

If I want to create a record:

ruby-1.9.2-p0 > NavItem.create
NoMethodError: undefined method `has_key?' for nil:NilClass
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/activesupport-3.0.0/lib/active_support/whiny_nil.rb:48:in `method_missing'
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.0/lib/active_record/attribute_methods/read.rb:69:in `class'
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.0/lib/active_record/persistence.rb:285:in `attributes_from_column_definition'
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.0/lib/active_record/locking/optimistic.rb:62:in `attributes_from_column_definition'
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.0/lib/active_record/base.rb:1396:in `initialize'
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.0/lib/active_record/base.rb:496:in `new'
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.0/lib/active_record/base.rb:496:in `create'
 from (irb):20
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.0/lib/rails/commands/console.rb:44:in `start'
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.0/lib/rails/commands/console.rb:8:in `start'
 from /Users/amueller/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.0/lib/rails/commands.rb:23:in `<top (required)>'
 from script/rails:6:in `require'
 from script/rails:6:in `<main>'

What can I do? I have other Models which works just fine. I dont know how to catch this error :( Are there any reserved words in the columns or do Rails try to apply some configuration over convention magic on this?

I use Rails3 with Ruby 1.9.2.

回答1:

You are using class (a reserved word) as one of your column names. If you change that, you should be fine.

回答2:

If you do not want to change the database schema, you can override the 'class' method:

class NavItem < ActiveRecord::Base
  def class
    NavItem
  end
end

来源：https://stackoverflow.com/questions/3651954/activerecord-doesnt-work-on-one-table

标签

ruby-on-rails

activerecord