Remove serialization of non-existing classes/objects

db/migrate/20190708192323_fix_unserializable_notification_options.rb

@@ -0,0 +1,39 @@
+class FixUnserializableNotificationOptions < ActiveRecord::Migration[5.1]
+  class Notification < ActiveRecord::Base
+    belongs_to :notification_type, :class_name => "FixUnserializableNotificationOptions::NotificationType"
+  end
+
+  class NotificationType < ActiveRecord::Base
+  end
+
+  # only used for testing
+  class CloudVolume < ActiveRecord::Base
+    self.inheritance_column = :_type_disabled
+  end
+
+  def up
+    invalid_options_ids = []
+    removed_records_ids = []
+    Notification.where.not(:options => nil).each do |n|
+      begin
+        # Options could have no longer available activerecord/activemodel classes from rails 5.0.0 -> 5.0.6, which will raise an ArgumentError on deserialization
+        # Fixing these to use 5.0.7+ smaller serialization format without all the private attributes is too hard, especailly since you can only read their YAML strings
+        # and make changes as a string, not as a Hash.
+        opts = YAML.load(n.options)
+      rescue ArgumentError
+        invalid_options_ids << n.id
+      else
+        begin
+          opts_subject = opts[:subject]
+          opts_subject.reload if opts_subject.respond_to?(:reload)
+        rescue ActiveRecord::RecordNotFound
+          # Options are readable. Options[:subject] is a AR::Base object but has been deleted.
+          removed_records_ids << n.id
+        end
+      end
+    end
+
+    Notification.where(:id => invalid_options_ids).update_all(:options => {:subject => "Unreadable"}.to_yaml)
+    Notification.where(:id => removed_records_ids).update_all(:options => {:subject => "Removed"}.to_yaml)
+  end
+end

spec/migrations/20190708192323_fix_unserializable_notification_options_spec.rb

@@ -0,0 +1,66 @@
+require_migration
+
+describe FixUnserializableNotificationOptions do
+  let(:notification_stub)      { migration_stub(:Notification) }
+  let(:notification_type_stub) { migration_stub(:NotificationType) }
+
+  migration_context :up do
+    it "fixes options[:subject] classes that don't exist" do
+      notification1 = notification_stub.create!(:notification_type => notification_type_stub.create!)
+      notification1.update(
+        :options =>
+          <<~OPTIONS
+            ---
+            :subject: !ruby/object:NonExistingCloudVolume
+              concise_attributes:
+              - !ruby/object:ActiveRecord::Attribute::FromDatabase
+                name: id
+                value_before_type_cast: 3
+              - !ruby/object:ActiveRecord::Attribute::FromDatabase
+                name: type
+                value_before_type_cast: NonExistingCloudVolume
+              - !ruby/object:ActiveRecord::Attribute::FromDatabase
+                name: name
+                value_before_type_cast: MyCloudVolume
+              new_record: false
+              active_record_yaml_version: 2
+          OPTIONS
+      )
+
+      expect { YAML.load(notification1.reload.options) }.to raise_error(ArgumentError)
+
+      migrate
+
+      expect(YAML.load(notification1.reload.options)[:subject]).to eq("Unreadable")
+    end
+
+    it "Sets options[:subject] where the record no longer exists" do
+      notification1 = notification_stub.create!(:notification_type => notification_type_stub.create!)
+      notification1.update(
+        :options =>
+          <<~OPTIONS
+            ---
+            :subject: !ruby/object:FixUnserializableNotificationOptions::CloudVolume
+              concise_attributes:
+              - !ruby/object:ActiveRecord::Attribute::FromDatabase
+                name: id
+                value_before_type_cast: 3
+              - !ruby/object:ActiveRecord::Attribute::FromDatabase
+                name: type
+                value_before_type_cast: ManageIQ::Providers::Openstack::CloudManager::CloudVolume
+              - !ruby/object:ActiveRecord::Attribute::FromDatabase
+                name: name
+                value_before_type_cast: MyCloudVolume
+              new_record: false
+              active_record_yaml_version: 2
+          OPTIONS
+      )
+
+      expect { YAML.load(notification1.reload.options)[:subject].reload }.to raise_error(ActiveRecord::RecordNotFound)
+
+      migrate
+
+      expect(YAML.load(notification1.reload.options)[:subject]).to eq("Removed")
+    end
+  end
+end