Removes item_subtype requirement for model-specific limits.

CHANGELOG.md

@@ -4,7 +4,8 @@ This project follows [semver 2.0.0](http://semver.org/spec/v2.0.0.html) and the
 recommendations of [keepachangelog.com](http://keepachangelog.com/).
 
 ## Unreleased
-
+- [#1309](https://github.com/paper-trail-gem/paper_trail/pull/1309) -
+  Removes `item_subtype` requirement when specifying model-specific limits.
 ### Breaking Changes
 
 - None

README.md

@@ -613,10 +613,6 @@ has_paper_trail limit: 2
 has_paper_trail limit: nil
 ```
 
-To use a per-model limit, your `versions` table must have an
-`item_subtype` column. See [Section
-4.b.1](https://github.com/paper-trail-gem/paper_trail#4b1-the-optional-item_subtype-column).
-
 ## 3. Working With Versions
 
 ### 3.a. Reverting And Undeleting A Model

lib/paper_trail/model_config.rb

@@ -18,11 +18,6 @@ class ModelConfig
       `abstract_class`. This is fine, but all application models must be
       configured to use concrete (not abstract) version models.
     STR
-    E_MODEL_LIMIT_REQUIRES_ITEM_SUBTYPE = <<~STR.squish.freeze
-      To use PaperTrail's per-model limit in your %s model, you must have an
-      item_subtype column in your versions table. See documentation sections
-      2.e.1 Per-model limit, and 4.b.1 The optional item_subtype column.
-    STR
     DPR_PASSING_ASSOC_NAME_DIRECTLY_TO_VERSIONS_OPTION = <<~STR.squish
       Passing versions association name as `has_paper_trail versions: %{versions_name}`
       is deprecated. Use `has_paper_trail versions: {name: %{versions_name}}` instead.
@@ -124,7 +119,6 @@ def setup(options = {})
       @model_class.send :include, ::PaperTrail::Model::InstanceMethods
       setup_options(options)
       setup_associations(options)
-      check_presence_of_item_subtype_column(options)
       @model_class.after_rollback { paper_trail.clear_rolled_back_versions }
       setup_callbacks_from_options options[:on]
     end
@@ -151,16 +145,6 @@ def cannot_record_after_destroy?
       ::ActiveRecord::Base.belongs_to_required_by_default
     end
 
-    # Some options require the presence of the `item_subtype` column. Currently
-    # only `limit`, but in the future there may be others.
-    #
-    # @api private
-    def check_presence_of_item_subtype_column(options)
-      return unless options.key?(:limit)
-      return if version_class.item_subtype_column_present?
-      raise Error, format(E_MODEL_LIMIT_REQUIRES_ITEM_SUBTYPE, @model_class.name)
-    end
-
     def check_version_class_name(options)
       # @api private - `version_class_name`
       @model_class.class_attribute :version_class_name

lib/paper_trail/reifier.rb

@@ -117,8 +117,6 @@ def reify_attributes(model, version, attrs)
       # this method returns the constant `Dog`. If `attrs["species"]` is blank,
       # this method returns the constant `Animal`. You can see this particular
       # example in action in `spec/models/animal_spec.rb`.
-      #
-      # TODO: Duplication: similar `constantize` in VersionConcern#version_limit
       def version_reification_class(version, attrs)
         inheritance_column_name = version.item_type.constantize.inheritance_column
         inher_col_value = attrs[inheritance_column_name]

lib/paper_trail/version_concern.rb

@@ -23,10 +23,6 @@ module VersionConcern
 
     # :nodoc:
     module ClassMethods
-      def item_subtype_column_present?
-        column_names.include?("item_subtype")
-      end
-
       def with_item_keys(item_type, item_id)
         where item_type: item_type, item_id: item_id
       end
@@ -379,16 +375,22 @@ def sibling_versions
     # The version limit can be global or per-model.
     #
     # @api private
-    #
-    # TODO: Duplication: similar `constantize` in Reifier#version_reification_class
     def version_limit
-      if self.class.item_subtype_column_present?
-        klass = (item_subtype || item_type).constantize
-        if klass&.paper_trail_options&.key?(:limit)
-          return klass.paper_trail_options[:limit]
-        end
+      if limit_option?(item.class)
+        item.class.paper_trail_options[:limit]
+      elsif base_class_limit_option?(item.class)
+        item.class.base_class.paper_trail_options[:limit]
+      else
+        PaperTrail.config.version_limit
       end
-      PaperTrail.config.version_limit
+    end
+
+    def limit_option?(klass)
+      klass.respond_to?(:paper_trail_options) && klass.paper_trail_options.key?(:limit)
+    end
+
+    def base_class_limit_option?(klass)
+      klass.respond_to?(:base_class) && limit_option?(klass.base_class)
     end
   end
 end

spec/paper_trail/config_spec.rb

@@ -52,17 +52,6 @@ module PaperTrail
         limited_bike.save
         assert_equal 2, limited_bike.versions.length
       end
-
-      context "when item_subtype column is absent" do
-        it "uses global version_limit" do
-          PaperTrail.config.version_limit = 6
-          names = PaperTrail::Version.column_names - ["item_subtype"]
-          allow(PaperTrail::Version).to receive(:column_names).and_return(names)
-          bike = LimitedBicycle.create!(name: "My Bike") # has_paper_trail limit: 3
-          10.times { bike.update(name: SecureRandom.hex(8)) }
-          assert_equal 7, bike.versions.length
-        end
-      end
     end
   end
 end

spec/paper_trail/version_limit_spec.rb

@@ -21,6 +21,21 @@ module PaperTrail
       # 4 versions = 3 updates + 1 create.
     end
 
+    it "cleans up old versions with limit specified on base class" do
+      PaperTrail.config.version_limit = 10
+
+      Animal.paper_trail_options[:limit] = 5
+      Dog.paper_trail_options = Animal.paper_trail_options.without(:limit)
+
+      dog = Dog.create(name: "Fluffy") # Dog specified has_paper_trail with no limit option
+
+      15.times do |i|
+        dog.update(name: "Name #{i}")
+      end
+      expect(Dog.find(dog.id).versions.count).to eq(6) # Dog uses limit option on base class, Animal
+      # 6 versions = 5 updates + 1 create.
+    end
+
     it "cleans up old versions" do
       PaperTrail.config.version_limit = 10
       widget = Widget.create