Add Primary Taxon feature to Spree products

- Introduced a new `primary_taxon_id` reference field in the `spree_products` table to associate a primary breadcrumb taxon with products.
- Updated the `Spree::Product` model to include a `belongs_to :primary_taxon` association, allowing optional linkage to a taxon.
- Modified the `Spree::Api::ApiConfiguration` to include `primary_taxon_id` in `product_attributes`, enabling API support for this attribute.
- Enhanced API tests to cover creation and updating of products with a primary taxon.
- Updated the admin product form to allow selection of a primary taxon.
- Improved frontend JavaScript for autocomplete functionality when selecting a primary taxon.
- Added `primary_taxon_id` to the list of permitted attributes for safe updates via the admin interface and API.
- Included test cases to verify the functionality of the `primary_taxon` association, ensuring proper model validation and API behavior.

This change is backward-compatible, allowing products to exist without a primary breadcrumb taxon while enhancing the product management capabilities in both the admin interface and API.

api/lib/spree/api_configuration.rb

@@ -7,7 +7,7 @@ class ApiConfiguration < Preferences::Configuration
     preference :product_attributes, :array, default: [
       :id, :name, :description, :available_on,
       :slug, :meta_description, :meta_keywords, :shipping_category_id,
-      :taxon_ids, :total_on_hand, :meta_title
+      :taxon_ids, :total_on_hand, :meta_title, :primary_taxon_id
     ]
 
     preference :product_property_attributes, :array, default: [:id, :product_id, :property_id, :value, :property_name]

api/spec/requests/spree/api/products_spec.rb

@@ -316,6 +316,13 @@ module Spree::Api
           expect(json_response["taxon_ids"]).to eq([taxon_1.id])
         end
 
+        it "puts primary taxon for the product" do
+          product_data[:primary_taxon_id] = taxon_1.id.to_s
+          post spree.api_products_path, params: { product: product_data }
+
+          expect(json_response["primary_taxon_id"]).to eq(taxon_1.id)
+        end
+
         # Regression test for https://github.com/spree/spree/issues/4123
         it "puts the created product in the given taxons" do
           product_data[:taxon_ids] = [taxon_1.id, taxon_2.id].join(',')
@@ -404,6 +411,13 @@ module Spree::Api
           expect(json_response["taxon_ids"]).to eq([taxon_1.id])
         end
 
+        it "puts primary taxon for the updated product" do
+          product.primary_taxon_id = taxon_2.id
+          put spree.api_product_path(product), params: { product: { primary_taxon_id: taxon_1.id } }
+
+          expect(json_response["primary_taxon_id"]).to eq(taxon_1.id)
+        end
+
         # Regression test for https://github.com/spree/spree/issues/4123
         it "puts the created product in the given taxons" do
           put spree.api_product_path(product), params: { product: { taxon_ids: [taxon_1.id, taxon_2.id].join(',') } }

backend/app/assets/javascripts/spree/backend/taxon_autocomplete.js

@@ -1,25 +1,49 @@
-$.fn.taxonAutocomplete = function () {
+$.fn.autocompleteTaxon = function (options) {
   'use strict';
 
+  var defaultOptions = {
+    multiple: true,
+    placeholder: Spree.translations.taxon_placeholder
+  };
+
+  options = $.extend({}, defaultOptions, options);
+
   this.select2({
-      placeholder: Spree.translations.taxon_placeholder,
-      multiple: true,
+      placeholder: options.placeholder,
+      multiple: options.multiple,
       initSelection: function (element, callback) {
-        var ids = element.val(),
-            count = ids.split(",").length;
-
-        Spree.ajax({
-          type: "GET",
-          url: Spree.pathFor('api/taxons'),
-          data: {
-            ids: ids,
-            per_page: count,
-            without_children: true
-          },
-          success: function (data) {
-            callback(data['taxons']);
-          }
-        });
+        var ids = element.val();
+
+        if (options.multiple) {
+          var count = ids.split(",").length;
+
+          Spree.ajax({
+            type: "GET",
+            url: Spree.pathFor('api/taxons'),
+            data: {
+              ids: ids,
+              per_page: count,
+              without_children: true
+            },
+            success: function (data) {
+              callback(data['taxons']);
+            }
+          });
+        } else {
+
+          Spree.ajax({
+            type: "GET",
+            url: Spree.pathFor('api/taxons'),
+            data: {
+              ids: ids,
+              per_page: 1,
+              without_children: true
+            },
+            success: function (data) {
+              callback(data['taxons'][0]);
+            }
+          });
+        }
       },
       ajax: {
         url: Spree.pathFor('api/taxons'),
@@ -53,5 +77,11 @@ $.fn.taxonAutocomplete = function () {
 };
 
 Spree.ready(function () {
-  $('#product_taxon_ids, .taxon_picker').taxonAutocomplete();
+  $('#product_taxon_ids, .taxon_picker').autocompleteTaxon({
+    multiple: true,
+  });
+
+  $('#product_primary_taxon_id').autocompleteTaxon({
+    multiple: false,
+  });
 });

backend/app/views/spree/admin/products/_form.html.erb

@@ -36,6 +36,13 @@
           <% end %>
         </div>
 
+        <div data-hook="admin_product_form_primary_taxons">
+          <%= f.field_container :primary_taxon do %>
+            <%= f.label :primary_taxon_id %><br>
+            <%= f.hidden_field :primary_taxon_id, value: @product.primary_taxon_id %>
+          <% end %>
+        </div>
+
         <div data-hook="admin_product_form_option_types">
           <%= f.field_container :option_types do %>
             <%= f.label :option_type_ids, plural_resource_name(Spree::OptionType) %>

backend/spec/features/admin/products/edit/taxons_spec.rb

@@ -26,7 +26,10 @@ def assert_selected_taxons(taxons)
       visit spree.edit_admin_product_path(product)
 
       assert_selected_taxons([taxon_1])
-      select2_search "Clothing", from: "Taxon"
+      within("[data-hook='admin_product_form_taxons']") do
+        select2_search "Clothing", from: "Taxon"
+      end
+
       assert_selected_taxons([taxon_1, taxon_2])
 
       # Without this line we have a flaky spec probably due to select2 not

core/app/models/spree/product.rb

@@ -32,6 +32,7 @@ class Product < Spree::Base
 
     belongs_to :tax_category, class_name: 'Spree::TaxCategory', optional: true
     belongs_to :shipping_category, class_name: 'Spree::ShippingCategory', inverse_of: :products, optional: true
+    belongs_to :primary_taxon, class_name: 'Spree::Taxon', optional: true
 
     has_one :master,
       -> { where(is_master: true).with_discarded },

core/config/locales/en.yml

@@ -179,6 +179,8 @@ en:
         name: Name
         on_hand: On Hand
         price: Master Price
+        primary_taxon_id: Primary Taxon
+        primary_taxon: Primary Taxon
         promotionable: Promotable
         shipping_category: Shipping Category
         sku: Master SKU

core/db/migrate/20250207104016_add_primary_taxon_to_products.rb

@@ -0,0 +1,7 @@
+class AddPrimaryTaxonToProducts < ActiveRecord::Migration[7.0]
+  def change
+    change_table :spree_products do |t|
+      t.references :primary_taxon, { to_table: :spree_taxons }
+    end
+  end
+end

core/lib/spree/permitted_attributes.rb

@@ -78,7 +78,7 @@ module PermittedAttributes
       :meta_keywords, :price, :sku, :deleted_at,
       :option_values_hash, :weight, :height, :width, :depth,
       :shipping_category_id, :tax_category_id,
-      :taxon_ids, :option_type_ids, :cost_currency, :cost_price
+      :taxon_ids, :option_type_ids, :cost_currency, :cost_price, :primary_taxon_id
     ]
 
     @@property_attributes = [:name, :presentation]

core/spec/models/spree/product_spec.rb

@@ -452,6 +452,22 @@ class Extension < Spree::Base
           end
         end
       end
+
+      describe "primary_taxon" do
+        it 'should belong to primary_taxon' do
+          expect(Spree::Product.reflect_on_association(:primary_taxon).macro).to eq(:belongs_to)
+        end
+
+        it 'should be optional' do
+          association = Spree::Product.reflect_on_association(:primary_taxon)
+          expect(association.options[:optional]).to be(true)
+        end
+
+        it 'should have a class_name of Spree::Taxon' do
+          association = Spree::Product.reflect_on_association(:primary_taxon)
+          expect(association.class_name).to eq('Spree::Taxon')
+        end
+      end
     end
   end
 
@@ -709,4 +725,13 @@ class Extension < Spree::Base
       end
     end
   end
+
+  it 'is valid with or without a primary_taxon' do
+    product_with_taxon = create(:product, primary_taxon: create(:taxon))
+
+    product_without_taxon = create(:product, primary_taxon: nil)
+
+    expect(product_with_taxon).to be_valid
+    expect(product_without_taxon).to be_valid
+  end
 end