Nested Resource Creation in Parent Form

Question

I have a class called Quote which has_many :line_items, as: :line_itemable (line_items are polymorphic). A quote must have at least one line_item upon creation, so in my Quote creation form I have a section dedicated to adding line items. My routes look like this:

resources :quotes, shallow: true do
  resources :line_items
end

which means my routes look like this:

                     POST  /quotes/:quote_id/line_items(.:format)      line_items#create
new_quote_line_item  GET   /quotes/:quote_id/line_items/new(.:format)  line_items#new

In the line items section of the quote form I have a button that, when clicked, links to the new_quote_line_item controller action to render a line_item creation modal. My issue is that since the quote hasn't been created yet it doesn't have :quote_id to use in the path. How can I go about achieving this the Rails Way™? I was considering using ajax but I'm not sure if that is overkill for this situation. Thanks for your help!

You don't display it? You said it: the Quote is not created yet, so why display a link to create LineItems belonging to a non-existing record? --- You may want to have a nested form that allows the end-user to create a Quote record AND a Line Item in the same form. If this is what you want, I'll post an answer — MrYoshiji, Jul 17 '14 at 20:40
I think that's what I'm currently trying to implement (unless I misunderstood your comment). I have a Quote creation form and within that I want the user to be able to add one or more line_items to the Quote that is about to be created. — davidicus, Jul 17 '14 at 20:46
check out `accepts_nested_attributes_for :nested_resource_name` ;) — MrYoshiji, Jul 17 '14 at 20:52
Just watched a railscast on that actually, I think that's what I need to do! Thanks :D — davidicus, Jul 17 '14 at 21:02

score 2 · Answer 1 · answered Jul 17 '14 at 21:04

You should user accepts_nested_attributes_for method in your model to accept attributes for LineItem and fields_for helper

Your model should looks like:

class Quote < ActiveRecord::Base
    accepts_nested_attributes_for :line_item
    ...
end

And you template like:

form_for @quote do |f|
    f.fields_for :line_items do |f2|
       ...
    end
    ...
end

score 1 · Accepted Answer · answered Jul 18 '14 at 09:04

Ajax

You wouldn't need ajax functionality for this - Ajax only allows you to pull data from the server asynchronously, which essentially means you don't have to reload the page.

--

Nested Attributes

What you're looking for, as alluded to by atomAltera sounds like accepts_nested_attributes_for - which allows you to create dependent models from the parent

It sounds to me that you'll need to create a quote before you try and populate line_items, which is actually quite simple using ActiveRecord:

#app/models/quote.rb
Class Quote < ActiveRecord::Base
   has_many :line_items
   accepts_nested_attributes_for :line_items
end

#app/controllers/quotes_controller.rb
Class QuotesController < ApplicationController
    def new
       @quote = Quote.new
       @quote.line_items.build
    end

    def create
       @quote = Quote.new(quote_params)
       @quote.save
    end

    private

    def quote_params
        params.require(:quote).permit(:quote, :attributes, :new, line_items_attributes: [:line, :items, :attributes])
    end
end

--

If you need any further information, please let me know!!

Nested Resource Creation in Parent Form

2 Answers2