Edit a collection item in _form for the parent

Rails
1

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

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?

Thanks,
~S

2

Could this be done with fields_for?

3

While I believe it is possible to use fields_for, as you mentioned in
your
replies, you do not have to. Here is a possible solution:

app/controllers/dogs_controller.rb

class DogsController < ApplicationController
def new
@dog = Dog.new
@legs = Leg.where(:dog_id => nil)
end
def create
@dog = Dog.new(params[:dog])
@dog.save
end
end

app/views/dogs/new.html.erb

<%= form_for @dog do |f| %>
<%= f.label :name %>:
<%= f.text_field :name %>

<% 4.times do |i| %>
<%= f.label “leg_#{i}”, “Leg #{i+1}” %>:
<%= select_tag ‘dog[leg_ids][]’,
options_from_collection_for_select(@legs, ‘id’, ‘description’), :id =>
“dog_leg_#{i}” %>

<% end %>

<%= f.submit %>
<% end %>

Note that you will have issues if you choose the same leg for any of the
selects. I hope this helps.

Andrew Ferk

4

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.

5

S,

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.

Andrew Ferk

6

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