Nested Attributes Error: no implicit conversion of String into Integer

Question

My Item model belongs to my Order model, and my Order model has many Items. When I attempt to pass in the following params:

{"utf8"=>"✓", "authenticity_token"=>"mPKksp+W5lZc7+lrc90trtCzX+UtPj4PI8boNf7vb+nneMF/J5SSBz8Nmh+CQ//DkmuVP2MJf7gS3oLqpZcM2Q==", "order"=>{"special_instructions"=>"", "item_attributes"=>{"topping_ids"=>["1", "2", "5"]}}, "commit"=>"Save"}

I receive the following error:

no implicit conversion of String into Integer

The error occurs in my create action in my Orders controller:

@order = Order.new(order_params)

This is what my params method looks like:

def order_params
  params.require(:order).permit(:completed, :special_instructions, items_attributes: [ :size, topping_ids: [] ])
end

Here is my Order model:

class Order < ActiveRecord::Base
  belongs_to :user
  has_many :items
  accepts_nested_attributes_for :items
end

Here is my Item model:

class Item < ActiveRecord::Base
  belongs_to :order
  has_many :sizes
  has_many :item_toppings
  has_many :toppings, through: :item_toppings
  has_many :inverse_item_toppings, class_name: 'ItemTopping', foreign_key: 'item_id'
  has_many :inverse_toppings, through: :inverse_item_toppings, source: :item
  accepts_nested_attributes_for :sizes, reject_if: :all_blank, allow_destroy: true
end

And here are the relevant parts of my schema

create_table "item_toppings", force: :cascade do |t|
  t.integer  "item_id"
  t.integer  "topping_id"
  t.datetime "created_at", null: false
  t.datetime "updated_at", null: false
end

create_table "items", force: :cascade do |t|
  t.string   "name"
  t.datetime "created_at",                  null: false
  t.datetime "updated_at",                  null: false
  t.string   "description"
  t.boolean  "seasonal",    default: false
  t.boolean  "active",      default: false
  t.string   "kind"
  t.integer  "toppings_id"
  t.string   "qualifier"
  t.integer  "order_id"
end

create_table "orders", force: :cascade do |t|
  t.datetime "created_at",                           null: false
  t.datetime "updated_at",                           null: false
  t.boolean  "completed",            default: false
  t.integer  "user_id"
  t.string   "special_instructions"
end

I'm pretty sure this has something to do with some part of my params needing to be an array instead of a hash, but I can't figure out my specific problem based off of similar posts I've worked through.

Answer 1

From what I can tell, because I have a has_many relationship, my items_attributes value needed to be an array of hashes:

{"items_attributes"=>[{"topping_ids"=>['1', '2', '5', '30']}]}

Instead of

{"items_attributes"=>{"topping_ids"=>['1', '2', '5', '30']}}

I believe the message error is related to Ruby expecting an array index – not a hash key.