[deploy] Add unique index on articles feed_source_url (#10208)

Co-authored-by: Molly Struve <mollylbs@gmail.com>

app/models/article.rb

@@ -53,7 +53,8 @@ class Article < ApplicationRecord
   validates :cached_tag_list, length: { maximum: 126 }
   validates :canonical_url, uniqueness: { allow_nil: true }
   validates :canonical_url, url: { allow_blank: true, no_local: true, schemes: %w[https http] }
-  validates :feed_source_url, uniqueness: { allow_blank: true }
+  validates :feed_source_url, uniqueness: { allow_nil: true }
+  validates :feed_source_url, url: { allow_blank: true, no_local: true, schemes: %w[https http] }
   validates :main_image, url: { allow_blank: true, schemes: %w[https http] }
   validates :main_image_background_hex_color, format: /\A#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})\z/
   validates :slug, presence: { if: :published? }, format: /\A[0-9a-z\-_]*\z/

db/migrate/20200904151734_add_unique_index_to_articles_feed_source_url.rb

@@ -0,0 +1,23 @@
+class AddUniqueIndexToArticlesFeedSourceUrl < ActiveRecord::Migration[6.0]
+  disable_ddl_transaction!
+
+  def up
+    # at this point in time the articles table has a non unique index on feed_source_url,
+    # we must replace that with a unique index
+    if index_exists?(:articles, :feed_source_url)
+      remove_index :articles, column: :feed_source_url, algorithm: :concurrently
+    end
+
+    unless index_exists?(:articles, :feed_source_url, unique: true)
+      add_index :articles, :feed_source_url, unique: true, algorithm: :concurrently
+    end
+  end
+
+  def down
+    if index_exists?(:articles, :feed_source_url, unique: true)
+      remove_index :articles, column: :feed_source_url, algorithm: :concurrently
+    end
+
+    add_index :articles, :feed_source_url, algorithm: :concurrently
+  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.define(version: 2020_09_02_204028) do
+ActiveRecord::Schema.define(version: 2020_09_04_151734) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "citext"
@@ -157,7 +157,7 @@ ActiveRecord::Schema.define(version: 2020_09_02_204028) do
     t.index ["canonical_url"], name: "index_articles_on_canonical_url", unique: true
     t.index ["comment_score"], name: "index_articles_on_comment_score"
     t.index ["featured_number"], name: "index_articles_on_featured_number"
-    t.index ["feed_source_url"], name: "index_articles_on_feed_source_url"
+    t.index ["feed_source_url"], name: "index_articles_on_feed_source_url", unique: true
     t.index ["hotness_score"], name: "index_articles_on_hotness_score"
     t.index ["path"], name: "index_articles_on_path"
     t.index ["public_reactions_count"], name: "index_articles_on_public_reactions_count", order: :desc

spec/models/article_spec.rb

@@ -38,7 +38,7 @@ RSpec.describe Article, type: :model do
     it { is_expected.to validate_presence_of(:title) }
     it { is_expected.to validate_presence_of(:user_id) }
     it { is_expected.to validate_uniqueness_of(:canonical_url).allow_nil }
-    it { is_expected.to validate_uniqueness_of(:feed_source_url).allow_blank }
+    it { is_expected.to validate_uniqueness_of(:feed_source_url).allow_nil }
     it { is_expected.to validate_uniqueness_of(:slug).scoped_to(:user_id) }
 
     it { is_expected.not_to allow_value("foo").for(:main_image_background_hex_color) }