我一直在尝试使用Ruby 2.4从Rails 5.0中的rails控制台添加记录。该模型被称为“AuditionGroup”
当我查找AuditionGroup时，一切都很完美：
2.4.0 :017 > AuditionGroup
=> AuditionGroup(id: integer, audition_date: date, audition_time: time, class: string, created_at: datetime, updated_at: datetime)
然后当我尝试添加新记录时，我收到以下错误消息：
2.4.0 :018 > newgroup = AuditionGroup.new
NoMethodError: undefined method `fetch_value' for nil:NilClass
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activerecord-5.0.1/lib/active_record/attribute_methods/read.rb:66:in `_read_attribute'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activerecord-5.0.1/lib/active_record/attribute_methods/read.rb:36:in `__temp__36c6163737'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activerecord-5.0.1/lib/active_record/core.rb:313:in `initialize'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activerecord-5.0.1/lib/active_record/inheritance.rb:65:in `new'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activerecord-5.0.1/lib/active_record/inheritance.rb:65:in `new'
from (irb):18
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/railties-5.0.1/lib/rails/commands/console.rb:65:in `start'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/railties-5.0.1/lib/rails/commands/console_helper.rb:9:in `start'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/railties-5.0.1/lib/rails/commands/commands_tasks.rb:78:in `console'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/railties-5.0.1/lib/rails/commands/commands_tasks.rb:49:in `run_command!'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/railties-5.0.1/lib/rails/commands.rb:18:in `<top (required)>'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:293:in `require'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:293:in `block in require'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:259:in `load_dependency'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:293:in `require'
from /Users/Nick/Sites/testapp/bin/rails:9:in `<top (required)>'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:287:in `load'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:287:in `block in load'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:259:in `load_dependency'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/activesupport-5.0.1/lib/active_support/dependencies.rb:287:in `load'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/commands/rails.rb:6:in `call'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/command_wrapper.rb:38:in `call'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/application.rb:191:in `block in serve'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/application.rb:161:in `fork'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/application.rb:161:in `serve'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/application.rb:131:in `block in run'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/application.rb:125:in `loop'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/application.rb:125:in `run'
from /Users/Nick/.rvm/gems/ruby-2.4.0/gems/spring-2.0.0/lib/spring/application/boot.rb:19:in `<top (required)>'
from /Users/Nick/.rvm/rubies/ruby-2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/Nick/.rvm/rubies/ruby-2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from -e:1:in `<main>'
这是我的AuditionGroup模型
class AuditionGroup < ApplicationRecord
self.table_name = "auditiongroups"
has_many :auditions
end
问题的根源是你有一个名为class的列。
谷歌在Rails中列出了“保留”字样，class就是其中之一。
这与this post有关。在这种情况下，将attr_accessor添加到您的类中以设置所有属性。