FIX: Destroy Drafts when increasing sequences (#27739)

Drafts used to be deleted instead of being destroyed. The callbacks that
clean up the upload references were not being called. As a result, the
upload references were not cleaned up and uploads were not deleted
either. This has been partially fixed in 9655bf3e.

app/models/draft_sequence.rb

@@ -20,12 +20,7 @@ class DraftSequence < ActiveRecord::Base
         RETURNING sequence
       SQL
 
-    DB.exec(
-      "DELETE FROM drafts WHERE user_id = :user_id AND draft_key = :draft_key AND sequence < :sequence",
-      draft_key: key,
-      user_id: user_id,
-      sequence: sequence,
-    )
+    Draft.where(user_id: user_id).where(draft_key: key).where("sequence < ?", sequence).destroy_all
 
     UserStat.update_draft_count(user_id)
 

db/migrate/20240705134114_clear_orphaned_draft_upload_references2.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class ClearOrphanedDraftUploadReferences2 < ActiveRecord::Migration[7.1]
+  def up
+    execute <<~SQL
+      DELETE
+      FROM
+        "upload_references"
+      WHERE
+        "upload_references"."target_type" = 'Draft' AND
+        "upload_references"."target_id" NOT IN (
+          SELECT "drafts"."id" FROM "drafts"
+        )
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

spec/models/draft_sequence_spec.rb

@@ -2,6 +2,7 @@
 
 RSpec.describe DraftSequence do
   fab!(:user)
+  fab!(:upload)
 
   describe ".next" do
     it "should produce next sequence for a key" do
@@ -14,11 +15,29 @@ RSpec.describe DraftSequence do
       2.times { expect(DraftSequence.next!(user, "test")).to eq(0) }
     end
 
-    it "updates draft count" do
-      Draft.create!(user: user, draft_key: "test", data: {})
-      expect(user.reload.user_stat.draft_count).to eq(1)
-      expect(DraftSequence.next!(user, "test")).to eq 1
-      expect(user.reload.user_stat.draft_count).to eq(0)
+    it "deletes old drafts and associated upload references" do
+      Draft.set(
+        user,
+        Draft::NEW_TOPIC,
+        0,
+        {
+          reply: "[#{upload.original_filename}|attachment](#{upload.short_url})",
+          action: "createTopic",
+          title: "New topic with an upload",
+          categoryId: 1,
+          tags: [],
+          archetypeId: "regular",
+          metaData: nil,
+          composerTime: 10_000,
+          typingTime: 10_000,
+        }.to_json,
+      )
+
+      expect { DraftSequence.next!(user, Draft::NEW_TOPIC) }.to change { Draft.count }.by(
+        -1,
+      ).and change { UploadReference.count }.by(-1).and change {
+                    user.reload.user_stat.draft_count
+                  }.by(-1)
     end
   end