我的桌面锦标赛有字段user_id，question_id，answer和我创建的关键字
Primary key (user_id, question_id)
但是当我想改变这样的答案字段时：
t=Tournament.where('question_id=200').first
t.answer=2
t.save
我有错误：
NoMethodError: undefined method `eq' for nil:NilClass
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activesupport-3.0.4/lib/active_support/whiny_nil.rb:48:in `method_missing'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/persistence.rb:255:in `update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/locking/optimistic.rb:77:in `update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/attribute_methods/dirty.rb:68:in `update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/timestamp.rb:60:in `update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/callbacks.rb:285:in `block in update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activesupport-3.0.4/lib/active_support/callbacks.rb:413:in `_run_update_callbacks'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/callbacks.rb:285:in `update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/persistence.rb:246:in `create_or_update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/callbacks.rb:277:in `block in create_or_update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activesupport-3.0.4/lib/active_support/callbacks.rb:423:in `_run_save_callbacks'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/callbacks.rb:277:in `create_or_update'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/persistence.rb:56:in `save!'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/validations.rb:49:in `save!'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/attribute_methods/dirty.rb:30:in `save!'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/transactions.rb:245:in `block in save!'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/transactions.rb:292:in `block in with_transaction_returning_status'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/connection_adapters/abstract/database_statements.rb:139:in `transaction'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/transactions.rb:207:in `transaction'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/transactions.rb:290:in `with_transaction_returning_status'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.4/lib/active_record/transactions.rb:245:in `save!'
from (irb):4
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.4/lib/rails/commands/console.rb:44:in `start'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.4/lib/rails/commands/console.rb:8:in `start'
from /home/marat/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.4/lib/rails/commands.rb:23:in `<top (required)>'
from script/rails:6:in `require'
任何人都可以帮助我吗？ 感谢。
答案 0 :(得分：0)
您是否根据标准的Rails创建了表格？
如果是，请参阅undefined method `eq' for nil:NilClass with rails 3 and ruby enterprise on ubuntu hardy