Nested forms in Ruby with checkboxes and many-to-many relationship - ruby-on-rails

Question

I am new to ruby and having a trouble in following scenario. I am trying to build a relationship between bill and items. In my case, I want to generate a bill at run time like when user clicks on create new bill, he is directed to a route like http://localhost:3000/bills/new and then he has a list of items from which he has to choose by checking the checkboxes and adding the quantity. I have 3 tables, Items, Bills, BillItems. They have following fields in them:
create_table "bill_items", force: :cascade do |t|
t.integer "bill_id"
t.integer "item_id"
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
t.integer "quantity"
end
create_table "bills", force: :cascade do |t|
t.integer "user_id"
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
end
create_table "items", force: :cascade do |t|
t.string "name"
t.float "price"
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
t.integer "category_id"
end
I have my models created like this:
Bill.rb
class Bill < ApplicationRecord
has_many :bill_items
has_many :items, through: :bill_items
accepts_nested_attributes_for :bill_items, :allow_destroy => true, :reject_if => :all_blank
end
Item.rb
class Item < ApplicationRecord
has_many :bill_items
has_many :bills, through: :bill_items
end
BillItem.rb
class BillItem < ApplicationRecord
belongs_to :bill
belongs_to :item
end
I have my form like:
<%= form_for #bill do |f| %>
<% if #allItems %>
<% #allItems.each_with_index do |item, index| %>
<tr class="table-success" scope="col-8">
<%= f.fields_for :bill_items do |s| %>
<td class="text-secondary"><%= item.category.name %></td>
<%= s.hidden_field :name, value: item.name %>
<td class="text-primary"><%= s.label item.name %></td>
<td><%= check_box_tag "item_ids[]", item.id, false, class: 'selectable' %> </td>
<td><%= s.number_field(:quantity, in: 1.0..100.0, step: 1) %></td>
<td><%= s.label :price, item.price %></td>
<% end %>
</tr>
<% end %>
<% end %>
</tbody>
</table>
<div class="form-group row justify-content-center">
<%= f.submit "Create Order with Selected items", class: "btn btn-secondary" %>
</div>
<% end %>
Then I have my controller setup like this:
def new
#bill = Bill.new
#bill_items = #bill.bill_items.build
end
def create
byebug
#bill = Bill.new(bill_params)
#bill.save
redirect_to new_bill_path
end
private
def bill_params
params.require(:bill).permit(bill_items_attributes: [:quantity, :item_ids])
end
When I run my code and send data to form and check params via byebug it shows me following params, while i selected two items, of ids 1 and 4:
<ActionController::Parameters {"authenticity_token"=>"hVnrTkWxWwuXqS4tb01INVkNwRaFooVERKe2L8YkXykyPqImKCVRrvqjhK8sA0Q26nsOS+dSNdLvIOPTfis8nQ==", "bill"=>{"bill_items_attributes"=>{"0"=>{"name"=>"sheer", "quantity"=>"2"}, "1"=>{"name"=>"burger", "quantity"=>""}, "2"=>{"name"=>"custurs", "quantity"=>""}, "3"=>{"name"=>"sib", "quantity"=>"4"}}}, "item_ids"=>["1", "4"], "commit"=>"Create Order with Selected items", "controller"=>"bills", "action"=>"create"} permitted: false>
Then I click submit and it only saves bill in the db and gives me error
Unpermitted parameter: :name
Unpermitted parameter: :name
Unpermitted parameter: :name
Unpermitted parameter: :name`
I have tried many techniques and couldn't find a solution. It will be very helpful if someone can help me with this. Even if I need to redesign my logic then do help me with this. Thanks.

Answer 1

<td><%= check_box_tag "item_ids[]", item.id, false, class: 'selectable' %> </td>
has to be
<td><%= check_box_tag "bill[item_ids[]]", item.id, false, class: 'selectable' %> </td>

Answer 2

Problem: There is a mismatch in nested attributes naming
Bill model is accepting nested attributes for :items
On Controller you have specified :bill_items_attributes and
Form generating fields for bill_items -
f.fields_for :bill_items
Solution: make it consistent
On Bill model -
accepts_nested_attributes_for :items
On Bill Controller -
permit(items_attributes:
On form new.html.erb -
f.fields_for :items
However this will create another problem for items_id, which I am not sure what are trying to achieve there.

Answer 3

You were getting those errors because you had hidden_field :name in form which is not required while submitting form. I removed that. However there was an issue with strong parameters and checkbox naming. I corrected strong params and kept checkbox naming descriptive so that you can see how form will generates it.
Try this code. I was able to create records with this code.
bills_controller.rb
private
def bill_params
params.require(:bill).permit(bill_items_attributes: [:quantity, :item_id])
end
new.html.erb
<%= form_for #bill do |f| %>
<% if #allItems %>
<% #allItems.each_with_index do |item, index| %>
<%= f.fields_for :bill_items do |s| %>
<tr class="table-success" scope="col-8">
<td class="text-primary"><%= s.label item.name %></td>
<td><%= check_box_tag "bill[bill_items_attributes][#{index}][item_id]", item.id, false, class: 'selectable' %> </td>
<td><%= s.number_field(:quantity, in: 1.0..100.0, step: 1) %></td>
<td><%= s.label :price, item.price %></td>
</tr>
<% end %>
<% end %>
<% end %>
<div class="form-group row justify-content-center">
<%= f.submit "Create Order with Selected items", class: "btn btn-secondary" %>
</div>
<% end %>