Rails form_for with nested resources - ruby-on-rails

Question

I'm having issues with routing a rails app to use a new and edit form.
The routes use the username within the URL.
lists GET /lists(.:format) lists#index
POST /user/:username/lists(.:format) lists#create
new_list GET /user/:username/lists/new(.:format) lists#new
edit_list GET /user/:username/lists/:id/edit(.:format) lists#edit
list GET /user/:username/lists/:id(.:format) lists#show
PATCH /user/:username/lists/:id(.:format) lists#update
PUT /user/:username/lists/:id(.:format) lists#update
DELETE /user/:username/lists/:id(.:format) lists#destroy
root GET / static#welcome
show_user GET /user/:id(.:format) users#show
My routes.rb-
get 'lists', to: 'lists#index', as: :lists, via: 'get'
scope 'user/:username' do
resources :lists, except: [:index]
end
My shared form, for use with updating and creating-
<%= form_for [#user, #list], url: list_path(#user, #list) do |f| %>
Using the above settings, I can edit lists correctly, but if I navigate to lists#new, I get the following error-
No route matches {:action=>"show", :controller=>"lists", :id=>nil, :username=>"test"} missing required keys: [:id]
If I pluralize the path in my form to be url: lists_path(#user, #list), then the new page will now load, but when trying to create I get the below error-
No route matches [POST] "/lists.test"
How can I fix these routes so I can use the same shared form for both edits and creating?
Adding controller code-
class ListsController < ApplicationController
before_action :set_list, only: [:show, :edit, :update, :destroy]
def index
#lists = List.all
end
def show
end
# GET /lists/new
def new
#list = List.new
#user = User.find_by(username: params[:username])
end
def edit
#user = User.find_by(username: params[:username])
end
def create
#list = current_user.lists.new(list_params)
respond_to do |format|
if #list.save
format.html { redirect_to list_path(#list.user.username, #list.id), notice: 'List was successfully created.' }
else
format.html { render :new }
end
end
end
def update
respond_to do |format|
if #list.update(list_params)
format.html { redirect_to list_path(#list.user.username, #list.id), notice: 'List was successfully updated.' }
else
format.html { render :edit }
end
end
end
def destroy
#list.destroy
respond_to do |format|
format.html { redirect_to lists_url, notice: 'List was successfully destroyed.' }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_list
#list = List.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def list_params
params.require(:list).permit(:name, :category, :user_id)
end
end

Answer 1

Try this - Change the :url value in the form_for to [[#list], :username => #user.username]
Like so:
<%= form_for [#user, #list], url: [[#list], :username => #user.username] do |f| %>