的ActiveRecord :: AssociationTypeMismatch在Ruby on Rails的3.2.1

Question

我有一些小测试，为Ruby on Rails的3.2.1这里是我的模型解释：

class Project < ActiveRecord::Base 
    has_many :tasks 
    accepts_nested_attributes_for :tasks 
end 

class Task < ActiveRecord::Base 
    belongs_to :project 
end 

但是，当我试图挽救任务为我的项目我得到错误：

irb(main):037:0> Project.first.tasks = [Task.first.id, Task.last.id] 
Project Load (0.2ms) SELECT "projects".* FROM "projects" LIMIT 1 
Task Load (0.1ms) SELECT "tasks".* FROM "tasks" LIMIT 1 
Task Load (0.1ms) SELECT "tasks".* FROM "tasks" ORDER BY "tasks"."id" DESC LIMIT 1 
ActiveRecord::AssociationTypeMismatch: Task(#70101178643360) expected, got Fixnum(#70101143633040) 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/associations/association.rb:204:in `raise_on_type_mismatch' 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/associations/collection_association.rb:308:in `block in replace' 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/associations/collection_association.rb:308:in `each' 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/associations/collection_association.rb:308:in `replace' 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/associations/collection_association.rb:41:in `writer' 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/activerecord-3.2.1/lib/active_record/associations/builder/association.rb:51:in `block in define_writers' 
from (irb):37 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/railties-3.2.1/lib/rails/commands/console.rb:47:in `start' 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/railties-3.2.1/lib/rails/commands/console.rb:8:in `start' 
from /Users/ka8725/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1/gems/railties-3.2.1/lib/rails/commands.rb:41:in `<top (required)>' 
from script/rails:6:in `require' 
from script/rails:6:in `<main>' 

请帮助我。为什么会引发这个异常？

Answer 1

Task.first.id和Task.last.id返回Fixnum对象类型数 您不能分配Project.first.tasks其期望类的任务，以数量的数组。