Question

I don’t know the best way to label this but basically, I have 3 models,

Course: A subject, which has many Sessions
Session: Has many Slots that make up one session
Slot: Has a date and time which it happens on

The idea is, if you are interested in a Course, you register to take a Session. Each Session will have the same number of Slots, but these could be at different times of the month (e.g. you could take a 5 day session on the 30th July to 3rd Aug, or the same session a week later, 6th Aug to 10th Aug)

So I need to try and set up my nested for, so you can add or remove Sessions, each one should have the same number of nested Slots (based on a number in a drop down somewhere up the form).

Can anyone think of a nice way of doing this? or even a nasty way? I’m having trouble 🙂

Update

I have it working with some JS and stuff, but now when it saves, it always errors saying Sessions slot session is not valid — its not setting the slots session_id to its parent session and its not setting the sessions course_id to the course

I can’t work out why. Anyone seen this before? The objects are in the has_many array…

Update 2

{"title"=>"test123", "description"=>"test123", "sessions_attributes"=>{"0"=>{"slots_attributes"=>{"0"=>{"when(3i)"=>"10", "when(2i)"=>"8", "when(1i)"=>"2012", "when(4i)"=>"10", "when(5i)"=>"00", "_destroy"=>"0"}, "1"=>{"when(3i)"=>"10", "when(2i)"=>"8", "when(1i)"=>"2012", "when(4i)"=>"10", "when(5i)"=>"00", "_destroy"=>"0"}, "2"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "3"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "4"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "5"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "6"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "7"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "8"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "9"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "10"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "11"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "12"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "13"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "14"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "15"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "16"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "17"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "18"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}, "19"=>{"when(3i)"=>"", "when(2i)"=>"", "when(1i)"=>"", "when(4i)"=>"", "when(5i)"=>"", "_destroy"=>"1"}}}}}

Update 3

adding this code before saving has fixed it, although I don’t know why I need it.

def apply_nested_models_hack
  ## HACK ##
  
  @course.sessions.each do |s|
    s.course = @course
    s.slots.each { |ss| ss.session = s }
  end
  
  ## /HACK ##
end

I’d like to know why the relationships aren’t getting set, even though I’ve fixed my issue I’ve not answered the question.

Update 4

It turns out this was not the nested forms but the fact I had:

validates :session, presence: true 

on Slot – ActiveRecord doesn’t set this side of the relationship until after saving, therefore it was considered invalid and wouldn’t save. I’d consider this a bug in AR as it should show the relationships as they were in the database, even if they haven’t been persisted yet.

Answer 1

It turns out this was not the nested forms but the fact I had:

validates :session, presence: true 

on Slot – ActiveRecord doesn’t set this side of the relationship until after saving, therefore it was considered invalid and wouldn’t save. I’d consider this a bug in AR as it should show the relationships as they were in the database, even if they haven’t been persisted yet.