Ruby on Rails的：在Rails的3.0.10

Question

abstract (1.0.0) 
actionmailer (3.2.2, 3.0.10, 3.0.5, 3.0.3, 2.3.5, 2.1.0) 
actionpack (3.2.2, 3.0.10, 3.0.5, 3.0.3, 3.0.0.beta3, 2.3.5, 2.1.0) 
activemodel (3.2.2, 3.0.10, 3.0.5, 3.0.3, 3.0.0.beta3) 
activerecord (3.0.10) 
activeresource (3.2.2, 3.0.10, 3.0.5, 3.0.3, 2.3.5, 2.1.0) 
activesupport (3.2.2, 3.0.10, 3.0.5, 3.0.3, 3.0.0.beta3, 2.3.5, 2.1.0) 
arel (3.0.2, 2.0.10, 2.0.6) 
bcrypt-ruby (3.0.1, 2.1.2) 
bson (1.1.5) 
bson_ext (1.1.5) 
builder (3.0.0, 2.1.2) 
bundle (0.0.1) 
bundler (1.1.3, 1.1.1, 1.1.0) 
cancan (1.6.7, 1.4.1) 
coffee-rails (3.2.2) 
coffee-script (2.2.0) 
coffee-script-source (1.3.1, 1.2.0) 
devise (2.0.4, 1.5.3, 1.1.5) 
erubis (2.7.0, 2.6.6) 
execjs (1.3.0) 
hike (1.2.1) 
i18n (0.6.0, 0.5.0, 0.3.7) 
journey (1.0.3) 
jquery-rails (2.0.2, 2.0.1) 
jquery_datepicker (0.3.4) 
json (1.6.6, 1.6.5) 
libv8 (3.3.10.4 x86-linux) 
mail (2.4.4, 2.2.19, 2.2.12, 2.2.7) 
memcache-client (1.8.5) 
mime-types (1.18, 1.17.2, 1.16) 
mongo (1.1.5) 
mongoid (2.0.0.beta.20) 
multi_json (1.2.0) 
mysql2 (0.3.11) 
nifty-generators (0.4.2) 
orm_adapter (0.0.7) 
polyglot (0.3.3, 0.3.1) 
rack (1.4.1, 1.2.5, 1.2.1, 1.1.3, 1.0.1) 
rack-cache (1.2) 
rack-mount (0.6.14, 0.6.13) 
rack-ssl (1.3.2) 
rack-test (0.6.1, 0.5.7, 0.5.6) 
rails (3.0.10) 
railties (3.2.2, 3.0.10, 3.0.5, 3.0.3) 
rake (0.9.2.2, 0.8.7) 
rdoc (3.12) 
rolify (3.1.0) 
sass (3.1.15) 
sass-rails (3.2.5) 
sprockets (2.1.2) 
sqlite3 (1.3.5) 
therubyracer (0.9.10) 
thor (0.14.6) 
tilt (1.3.3) 
treetop (1.4.10, 1.4.9) 
tzinfo (0.3.33, 0.3.32, 0.3.23) 
uglifier (1.2.4) 
warden (1.1.1, 1.0.3) 
will_paginate (3.0.3, 3.0.pre2) 

上方沒有方法錯誤是創業板名單..

我保持這將對每一項任務，但命令task=Todo.tasks.new導致在規定的子任務的基本待辦事項沒有方法錯誤

amrit@PC148881:~/mytodos$ rails console 
Loading development environment (Rails 3.0.10) 
1.9.2-p290 :001 > todo=todo.first 
NoMethodError: You have a nil object when you didn't expect it! 
You might have expected an instance of Array. 
The error occurred while evaluating nil.first 
    from (irb):1 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands/console.rb:44:in `start' 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands/console.rb:8:in `start' 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands.rb:23:in `<top (required)>' 
    from script/rails:6:in `require' 
    from script/rails:6:in `<main>' 
1.9.2-p290 :002 > todo=Todo.first 
=> #<Todo id: 1, name: "Office", description: "work to be completed at office", created_at: "2012-04-17 08:53:35", updated_at: "2012-04-17 08:53:35"> 
1.9.2-p290 :003 > task=Todo.tasks.new 
NoMethodError: undefined method `tasks' for #<Class:0xae32588> 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/activerecord-3.0.10/lib/active_record/base.rb:1014:in `method_missing' 
    from (irb):3 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands/console.rb:44:in `start' 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands/console.rb:8:in `start' 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands.rb:23:in `<top (required)>' 
    from script/rails:6:in `require' 
    from script/rails:6:in `<main>' 
1.9.2-p290 :004 > ^C 
1.9.2-p290 :004 > t=Task.new 
=> #<Task id: nil, description: nil, due_date: nil, due_time: nil, completed: nil, todo_id: nil, created_at: nil, updated_at: nil> 
1.9.2-p290 :005 > t.description="meeting" 
=> "meeting" 
1.9.2-p290 :006 > t.save 
=> true 
1.9.2-p290 :007 > task=Todo.tasks.new 
NoMethodError: undefined method `tasks' for #<Class:0xae32588> 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/activerecord-3.0.10/lib/active_record/base.rb:1014:in `method_missing' 
    from (irb):7 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands/console.rb:44:in `start' 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands/console.rb:8:in `start' 
    from /home/amrit/.rvm/gems/ruby-1.9.2-p290@1.9.2/gems/railties-3.0.10/lib/rails/commands.rb:23:in `<top (required)>' 
    from script/rails:6:in `require' 
    from script/rails:6:in `<main>' 
1.9.2-p290 :008 > 

Answer 1

謝謝你！我得到了答案，我在創建實例時犯了一個錯誤，我試着這樣做：t = Todo.new t = Todo.tasks.new而不是：t = Todo.new x = t.tasks。

Answer 2

您可能會無意中在類而不是實例上調用tasks。試試這個：

task=todo.tasks.new 

Answer 3

好像這是你在做

todo=todo.first一個簡單的拼寫錯誤，但什麼是第二todo？堂妹好像你還沒有定義它，但在第二個例子中，你做

todo=Todo.first 

檢查你的資本「T」做第二個例子，嘗試糾正或者你可以嘗試

todo = Todo.all.first 

（假設你有一個叫做藤一AR模型）

歡呼