edit a collection item in _form for the parent

Say I have a Dog that has_may legs (In this case we don’t care how many). In the _form for Dog, I would like to assign a pre-existing let to him. I would like to do something like this:

<%= f.collection_select :leg_1, Leg.select { |l| l.dog_id == nil }, :id, :description %>
<%= f.collection_select :leg_2, Leg.select { |l| l.dog_id == nil }, :id, :description %>

Then in my controller’s create action:

@dog = Dog.new(params[:dog])
leg = Leg.find(params[:leg_1])
leg.dog = @dog

The problem is that the collection_select is trying to set the leg_1 value as part of Dog, which of course does not exist. Do I need to create ‘view model’ for doing this?


Could this be done with fields_for?

Thank. Yeah, I basically ended up doing something similar. I use ‘leg[]’ in my select tag, and then manually hooked things up in the back end… I wonder if in your solution if things would have been connected for me? Never mind just tried it, I still have to hook things up manually in the backend.

Thanks for the help, good to know that I am not crazy.


You should not have to do any manual association. If you have params[:dog][:leg_ids] = […], it should work; you may need to set attr_accessible :leg_ids in your Dog model. Show your solution, and maybe we can refactor it to use less code.

Ahhh, got it working as you said now. Great thanks.