用戶通過任務有很多角色

Question

我想能夠爲每個用戶分配多個角色，然後用User.first.roles之類的東西重新獲得他們，但是我迷路了，您會如何使用rails控制檯進行操作？我在模型中做了什麼錯誤？

u = User.first 

User Load (0.1ms) SELECT "users".* FROM "users" LIMIT 1 
=> #<User id: 18 [...]> 

1.9.3-p194 :004 > u.roles 
NameError: uninitialized constant User::Assignment 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/inheritance.rb:119:in `compute_type' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/reflection.rb:172:in `klass' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/reflection.rb:385:in `block in source_reflection' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/reflection.rb:385:in `collect' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/reflection.rb:385:in `source_reflection' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/reflection.rb:508:in `check_validity!' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/associations/association.rb:26:in `initialize' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/associations/collection_association.rb:24:in `initialize' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/associations/has_many_through_association.rb:10:in `initialize' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/associations.rb:157:in `new' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/associations.rb:157:in `association' 
    from [path]/ruby-1.9.3-p194/gems/activerecord-3.2.3/lib/active_record/associations/builder/association.rb:44:in `block in define_readers' 
    from (irb):4 
    from [path]/ruby-1.9.3-p194/gems/railties-3.2.3/lib/rails/commands/console.rb:47:in `start' 
    from [path]/ruby-1.9.3-p194/gems/railties-3.2.3/lib/rails/commands/console.rb:8:in `start' 
    from [path]/ruby-1.9.3-p194/gems/railties-3.2.3/lib/rails/commands.rb:41:in `<top (required)>' 
    from script/rails:6:in `require' 
    from script/rails:6:in `<main>' 

型號/ user.rb

class User < ActiveRecord::Base 
attr_accessible :name, :email, :password, :password_confirmation, :role_id 
has_many :assignments 
has_many :roles, through: :assignments 
#more code... 
end 

型號/ role.rb

class Role < ActiveRecord::Base 
attr_accessible :name 
has_many :assignments 
has_many :users, through: :assignments 
end 

型號/ assignments.rb

class Assignments < ActiveRecord::Base 
attr_accessible :role_id, :user_id 
belongs_to :user 
belongs_to :role 
end 

schema.rb：http://cl.ly/323n1t0Q1t390y1M2S0E

Answer 1

將模型文件models/assignments.rb的名稱更改爲models/assignment.rb，將其類名稱從class Assignments更改爲class Assignment。模型名稱應該是單一的軌道約定。因此，當您運行u.roles時，它正在尋找「分配而不分配」。