Question

This might be a case of me being blind…
Somehow I cannot get my layout_positions_attributes to arrive at layout_positions

l = Layout.new
…
[17] pry(main)> l.layout_positions
=> []
[18] pry(main)> l.layout_positions_attributes=[{:name=>'xxx'}]
=> [{:name=>"xxx"}]
[19] pry(main)> l.layout_positions
=> [] # WTF!
[20] pry(main)> l.layout_positions.build({:name=>'xxx'})
=> #<LayoutPosition id: nil, name: "xxx", active: true, columns: nil, rows: nil, layout_id: nil, pos: -1>
[21] pry(main)> l.layout_positions
=> [#<LayoutPosition id: nil, name: "xxx", active: true, columns: nil, rows: nil, layout_id: nil, pos: −1>]

The parent class:

class Layout < ActiveRecord::Base
  attr_accessible :name, :active, :layout_positions_attributes
  has_many :layout_positions
  accepts_nested_attributes_for :layout_positions,
                                :reject_if => lambda { |a| a[:content].blank? },
                                :allow_destroy => true
  validates_presence_of :name
end

And where the attributes should go…

class LayoutPosition < ActiveRecord::Base
  attr_accessible :name, :active, :columns, :rows, :pos
  belongs_to :layout
  validates_presence_of :name
end

Answer 1

You’re telling it to reject it if the content for the layout_position object is blank. In your example, above “WTF”, you’re not passing through any content. Therefore this is deleting the attributes.

Calling build doesn’t rely on accepts_nested_attributes_for and so will work just fine.