Migrate first master variant image to product image

(cherry picked from commit 21cba0aa13)

db/migrate/20230603181837_migrate_master_image_to_product.rb

@@ -0,0 +1,46 @@
+class MigrateMasterImageToProduct < ActiveRecord::Migration[7.0]
+  def up
+    # Multiple images can be present per variant, ordered by the `position` column.
+    # In some cases if the image was deleted and another was added, the numbering can be off,
+    # so the positions of the images might be 3,4,5 or 2,3 and the "first" image would be position 2
+    # or position 3 in those cases (instead of 1).
+    #
+    # This finds the image for each variant with the lowest `position` out of the current images and
+    # sets it's `position` to 1 (if it's not already 1) to make it easier to operate on the "first" image.
+    renumber_first_image
+
+    # Switches the association of the first image for each master variant to it's product
+    migrate_master_images
+  end
+
+  def renumber_first_image
+    ActiveRecord::Base.connection.execute(<<-SQL
+      UPDATE spree_assets
+      SET position = '1'
+      FROM (
+        SELECT DISTINCT ON (viewable_id) id, viewable_id, position
+        FROM spree_assets
+        WHERE spree_assets.viewable_type = 'Spree::Variant'
+        ORDER BY viewable_id, position ASC
+      ) variant_first_image
+      WHERE spree_assets.id = variant_first_image.id
+      AND spree_assets.position != '1'
+    SQL
+    )
+  end
+
+  def migrate_master_images
+    ActiveRecord::Base.connection.execute(<<-SQL
+      UPDATE spree_assets
+      SET viewable_type = 'Spree::Product',
+          viewable_id = spree_variants.product_id
+      FROM spree_variants
+      WHERE spree_variants.id = spree_assets.viewable_id
+        AND spree_variants.is_master = true
+        AND spree_variants.deleted_at IS NULL
+        AND spree_assets.viewable_type = 'Spree::Variant'
+        AND spree_assets.position = '1'
+    SQL
+    )
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.0].define(version: 2023_05_22_120633) do
+ActiveRecord::Schema[7.0].define(version: 2023_06_03_181837) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_stat_statements"
   enable_extension "plpgsql"

spec/factories/asset_factory.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :asset, class: Spree::Asset do
+    viewable { nil }
+    position { 1 }
+    type { "Spree::Image" }
+  end
+end

spec/migrations/migrate_master_images_spec.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require_relative '../../db/migrate/20230603181837_migrate_master_image_to_product'
+
+describe MigrateMasterImageToProduct do
+  subject { MigrateMasterImageToProduct.new }
+
+  let!(:product1) { create(:product) }
+  let!(:master1) { create(:variant, product: product1, is_master: true) }
+  let!(:image1) { create(:asset, viewable: master1, position: 1) }
+  let!(:image2) { create(:asset, viewable: master1, position: 2) }
+
+  let!(:product2) { create(:product) }
+  let!(:master2) { create(:variant, product: product2, is_master: true) }
+  let!(:image3) { create(:asset, viewable: master2, position: 2) }
+  let!(:image4) { create(:asset, viewable: master2, position: 3) }
+  let!(:image5) { create(:asset, viewable: master2, position: 4) }
+
+  describe "#renumber_first_image" do
+    it "updates the first image to position 1 if it's not already 1" do
+      subject.renumber_first_image
+
+      expect(image1.reload.position).to eq 1
+      expect(image3.reload.position).to eq 1
+    end
+  end
+
+  describe "#migrate_master_images" do
+    before { image3.update_columns(position: 1) }
+
+    it "migrates the master variant image to the product" do
+      subject.migrate_master_images
+
+      expect(product1.reload.image.id).to eq image1.id
+      expect(product2.reload.image.id).to eq image3.id
+    end
+  end
+end