How do I create a parent from child in Rails?

Question

In my app I'm receiving this error.

Couldn't find Vendor with ID=1 for InventoryItem with ID=

InventoryItem.rb

belongs_to :vendor
accepts_nested_attributes_for :vendor

Vendor.rb

has_many :inventory_items

_form.html.erb

<%= simple_nested_form_for @inventory_item, :html => {:class => 'form-inline' } do |f| %>                                                                                     


  <h2>Inventory Data</h2>
  <%= f.input :name, :input_html => {:autocomplete => :off, :placeholder => 'Item Name' }%> 
    <%= f.input :id, :as => :hidden %>

    <%= f.simple_fields_for :vendor do |v| %>
      <%= v.input :name, :label => 'Vendor name', :input_html => {:autocomplete => :off, :placeholder => 'Vendor Name' } %>
      <%= v.input :id, :as => :hidden %>
    <% end %>
<% end %>
  ----snip----

My parameters hash comes out accordingly

{"utf8"=>"✓",
 "authenticity_token"=>"ZY9fum4XGStTMNbpRQxrzmP7PT3A6BUU+wOymV0fZ/c=",
 "inventory_item"=>{"name"=>"testing",
 "id"=>"7678",
 "vendor_attributes"=>{"name"=>"test",
 "id"=>"1"},
 "item_instances_attributes"=>{"0"=>{"barcode"=>"",
 "funding_source"=>"",
 "serial"=>"",
 "version"=>"",
 "website_id"=>"",
 "item_type"=>"Retail",
 "type_of_at"=>"Vision",
 "os"=>"Mac",
 "registration_key"=>"",
 "dealer_price"=>"",
 "retail_price"=>"",
 "reuse_price"=>"",
 "estimated_current_purchase_price"=>"",
 "cost_to_consumer_for_loan"=>"",
 "repair_status"=>"Working",
 "date_reviewed"=>"10-15-2012",
 "qr_url"=>"",
 "location"=>"",
 "restrictions"=>"",
 "notes"=>""}}},
 "commit"=>"Create Inventory item"}

inventory_items_controller.rb

def create
    params[:inventory_item].delete(:estimated_dealer_price)
    @inventory_item = InventoryItem.create(params[:inventory_item])
    @inventory_item.name = inventory_item.name.downcase

    if inventory_item.save
      redirect_to(inventory_items_path, :notice => "Item created.")
    else
      render 'new'
    end 
  end 

The controller is receiving the id and attempting to find the right vendor (which exists), has issues when left to the built-in rails methods for finding the vendor and building the relationship.

The input for vendor name is an autocomplete which assigns the id to the hidden id field.

possible solutions:

1. Handle manually in the controller, fetching the id and building the relationship
2. change the form so that the inventory_item.vendor.name autocompletes inventory_item.vendor_id and strip the name if an id is provided
3. fix something I'm missing?

Answer 1

Sounds like you have it in reverse, normally child should not be creating parent records and you should check if its posible to make it in more standard approach of parent child relationship.

That being said you can do something like this

InventoryItem << ActiveRecord::Base
  belongs_to :vendor
  def vendor_attributes=(params)
    self.vendor = Vendor.find(params[:id]) || Vendor.create_by_name!(params[:name])
  end
end