From 39a6de3d73c442b470611c63b52f39eff505e70b Mon Sep 17 00:00:00 2001
From: Roman Rizzi <rizziromanalejandro@gmail.com>
Date: Thu, 7 Apr 2022 18:02:11 -0300
Subject: [PATCH] FIX: Clean required category tag groups with invalid
 tag_group ids (#16414)

The category table's required_tag_group_id contained references to deleted tag groups, which we copied to the new table. The new serializer tries to get the associated tag group name but fails because the tag group is nil.

This PR adds an inner join in the original migration to make sure tag groups still exist and adds a new post-migration to fix already migrated sites.
---
 ...745_create_category_required_tag_groups.rb |  3 ++-
 ..._required_tag_groups_without_tag_groups.rb | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 db/post_migrate/20220407195246_remove_category_required_tag_groups_without_tag_groups.rb

diff --git a/db/migrate/20220401130745_create_category_required_tag_groups.rb b/db/migrate/20220401130745_create_category_required_tag_groups.rb
index 1d0bfbb4270..dd054a9e11b 100644
--- a/db/migrate/20220401130745_create_category_required_tag_groups.rb
+++ b/db/migrate/20220401130745_create_category_required_tag_groups.rb
@@ -17,7 +17,8 @@ class CreateCategoryRequiredTagGroups < ActiveRecord::Migration[6.1]
       (category_id, tag_group_id, min_count, updated_at, created_at)
       SELECT c.id, c.required_tag_group_id, c.min_tags_from_required_group, NOW(), NOW()
       FROM categories c
-      WHERE c.required_tag_group_id IS NOT NULL
+      INNER JOIN tag_groups tg ON tg.id = c.required_tag_group_id
+      WHERE tg.id IS NOT NULL
     SQL
   end
 
diff --git a/db/post_migrate/20220407195246_remove_category_required_tag_groups_without_tag_groups.rb b/db/post_migrate/20220407195246_remove_category_required_tag_groups_without_tag_groups.rb
new file mode 100644
index 00000000000..e8cd6388e39
--- /dev/null
+++ b/db/post_migrate/20220407195246_remove_category_required_tag_groups_without_tag_groups.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class RemoveCategoryRequiredTagGroupsWithoutTagGroups < ActiveRecord::Migration[6.1]
+  def up
+    execute <<~SQL
+      DELETE FROM category_required_tag_groups
+      WHERE id IN (
+        SELECT crtg.id
+        FROM category_required_tag_groups crtg
+        LEFT OUTER JOIN tag_groups tg ON crtg.tag_group_id = tg.id
+        WHERE tg.id IS NULL
+      )
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end