Rails activeadmin save data in associated table - ruby-on-rails

Question

I have one table for Products and the product can either be in the interior or exterior or both. So I created another table to save the Products location. Now when admin adds the product I have provided the option to select the location(s) the product can be in, but when it is posted the code says the field can't be blank because of the validation. I am not sure what I am missing or the approach is wrong.
The product model:
class Product < ApplicationRecord
validates :name, presence: true
has_many :product_locations
accepts_nested_attributes_for :product_locations
end
The product location model:
class ProductLocation < ApplicationRecord
enum locations: [:exterior, :interior]
validates :location, presence: true
validates :product_id, presence: true
belongs_to :product
end
The ActiveAdmin file for Product:
ActiveAdmin.register Product do
permit_params :name, product_locations_attributes: {}
actions :all, except: [:show, :destroy]
filter :name
index do
column 'Product Name', :name
actions
end
form do |f|
f.semantic_errors *f.object.errors.keys
f.inputs "Products" do
f.input :name
end
f.has_many :product_locations do |location|
location.inputs "Locations" do
location.input :location, as: :select, multiple: true, collection: ProductLocation.locations.keys
end
end
f.actions
end
controller do
def scoped_collection
Product.where(user_id: nil)
end
end
end
I get a multi-select for the locations which has "Interior" and "Exterior" for selection, but it says the field can't be blank when I select the location and submit the form
The error on save click I get is:
Location can't be blank
The params that get posted are:
Parameters: {"utf8"=>"✓", "product"=>{"name"=>"Test Product", "product_locations_attributes"=>{"0"=>{"location"=>["0", "1"]}}}, "commit"=>"Create Product"}

Answer 1

First, the permit attributes should be,
product_locations_attributes: [:id, :location]
Then, in your form
location.input :location, as: :select, multiple: true, collection: ProductLocation.locations.keys
Since ProductLocation.locations is an array, array.keys is an invalid method.
So, use directly
location.input :location, as: :select, multiple: true, collection: ProductLocation.locations.map { |n| [n,n] }
To store an array of multiple values take serialize field as an array,
class ProductLocation < ApplicationRecord
enum locations: [:exterior, :interior]
serialize :location, Array
validates :location, presence: true
validates :product_id, presence: true
belongs_to :product
end
Note: Inorder to get the serialize work, you need to have the dataType of the location as a text. If it is not text run a migration to change to text data type
Reason for text field: Rails will convert all those object into plain text when storing in database