Rails: unable to set any attribute of child model

I'm having a problem instantiating a ListItem object with specified attributes. For some reason all attributes are set 开发者_StackOverflowto nil even if I specify values. However, if I specify attributes for a List, they retain their values.

Attributes for a List retain their values:

>> list = List.new(:id => 20, :name => "Test List")
=> #<List id: 20, name: "Test List">

Attributes for a ListItem don't retain their values:

>> list_item = ListItem.new(:id => 17, :list_id => 20, :name => "Test Item")
=> #<ListItem id: nil, list_id: nil, name: nil>

I thought the id was the only attribute not retaining its value but realized that setting any attribute for a ListItem gets set to nil.

I added validates_associated :list_items to the List class which alleviated an error regarding the name attribute being blank.

However, I still can't explicitly assign an id to a new ListItem.

list.rb:

class List < ActiveRecord::Base
    has_many :list_items, :dependent => :destroy

    accepts_nested_attributes_for :list_items, 
                                  :reject_if => lambda { |a| a[:name].blank? }, 
                                  :allow_destroy => true
end

list_item.rb:

class ListItem < ActiveRecord::Base
    belongs_to :list

    validates_presence_of :name  
end

schema.rb

ActiveRecord::Schema.define(:version => 20100506144717) do

  create_table "list_items", :force => true do |t|
    t.integer  "list_id"       
    t.string   "name"       
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "lists", :force => true do |t|
    t.string   "name"        
    t.datetime "created_at"
    t.datetime "updated_at"        
  end

end

I created your models and tables in my local setup. I didn't encounter any errors. There must be some class name conflict OR you have some before_save filters/observers resetting the values.

Note

I would change the model names to be bit more specific. It is very easy to run in to class name conflicts with names like List and ListItem

Hmm,

I've encountered something similar when validations don't work properly. Try

ListItem.create!(:id => 17, :list_id => 20, :name => "Test Item")

This should give you more direct feedback if the model is invalid.