fix: Allow to use attribute aliases

Add sti classic tests with alias

Make aliases work

Fix cops

TODO.md

@@ -6,4 +6,5 @@
 - [ ] Rails 5 support
 - [ ] test permitted attributes
 - [ ] `self.abstract_class = true`
+- [ ] scoping…
 - [ ] ~~use `type` column with enum, int, string, etc.~~

lib/discriminable.rb

@@ -36,21 +36,27 @@ def discriminable(**options)
 
       attribute, map = options.first
 
+      # E.g. { value: "ClassName" }
       self.discriminable_map = map.with_indifferent_access
 
       # Use first key as default discriminator
       # { a: "C", b: "C" }.invert => { "C" => :b }
       # { a: "C", b: "C" }.to_a.reverse.to_h.invert => { "C" => :a }
+      # E.g. { "ClassName" => :value }
       self.discriminable_inverse_map = map.to_a.reverse.to_h.invert
-      self.inheritance_column = attribute.to_s
+
+      attribute = attribute.to_s
+      self.inheritance_column = attribute_aliases[attribute] || attribute
     end
 
     def discriminable_by(attribute)
       raise "Subclasses should not override .discriminable_by" unless base_class?
 
       self.discriminable_map ||= discriminable_map_memoized
       self.discriminable_inverse_map ||= discriminable_inverse_map_memoized
-      self.inheritance_column = attribute.to_s
+
+      attribute = attribute.to_s
+      self.inheritance_column = attribute_aliases[attribute] || attribute
     end
 
     def discriminable_as(*values)
@@ -61,6 +67,7 @@ def discriminable_as(*values)
       end
     end
 
+    # This is the value of the discriminable attribute
     def sti_name
       discriminable_inverse_map[name]
     end
@@ -78,8 +85,7 @@ def subclass_from_attributes(attrs)
       attrs = attrs.to_h if attrs.respond_to?(:permitted?)
       return unless attrs.is_a?(Hash)
 
-      value = attrs.with_indifferent_access[inheritance_column]
-      value = base_class.type_for_attribute(inheritance_column).cast(value)
+      value = discriminable_value(attrs)
       sti_class_for(value)
     end
 
@@ -94,5 +100,12 @@ def discriminable_inverse_map_memoized
         map[value] = value.constantize.discriminable_values&.first
       end
     end
+
+    def discriminable_value(attrs)
+      attrs = attrs.with_indifferent_access
+      value = attrs[inheritance_column]
+      value ||= attrs[attribute_aliases.invert[inheritance_column]]
+      base_class.type_for_attribute(inheritance_column).cast(value)
+    end
   end
 end

test/test_open_closed_principle_aliased_integer.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require "helper"
+
+class TestOpenClosedPrincipleAliasedInteger < Case
+  class Property < ActiveRecord::Base
+    include Discriminable
+
+    alias_attribute :kind, :kind_with_some_postfix
+
+    # No enum this time
+    discriminable_by :kind
+  end
+
+  class NumberProperty < Property
+    discriminable_as 1
+  end
+
+  class OptionProperty < Property
+    discriminable_as 2, 3
+  end
+
+  def setup
+    ActiveRecord::Schema.define do
+      create_table :properties do |t|
+        t.integer :kind_with_some_postfix, limit: 1, null: true
+      end
+    end
+  end
+
+  def test_sti_name_default
+    assert_equal 1, NumberProperty.sti_name
+    assert_equal 2, OptionProperty.sti_name
+  end
+
+  def test_creation_and_loading
+    assert_equal 1, NumberProperty.create.kind
+    assert_equal 2, OptionProperty.create.kind
+    assert_instance_of NumberProperty, Property.first
+    assert_instance_of OptionProperty, Property.last
+  end
+
+  def test_creation_using_parent
+    assert_instance_of NumberProperty, Property.create(kind: 1)
+    assert_instance_of OptionProperty, Property.create(kind: 3)
+  end
+
+  def test_building
+    assert_instance_of NumberProperty, Property.new(kind: 1)
+    assert_instance_of OptionProperty, Property.new(kind: 2)
+    assert_instance_of OptionProperty, Property.new(kind: 3)
+  end
+end

test/test_sti_aliased.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+require "helper"
+
+class TestStiAliased < Case
+  class Order < ActiveRecord::Base
+    self.inheritance_column = "type_with_some_postfix"
+    alias_attribute :type, :type_with_some_postfix
+  end
+
+  class Cart < Order
+  end
+
+  def setup
+    ActiveRecord::Schema.define do
+      create_table :orders do |t|
+        t.string :type_with_some_postfix
+      end
+    end
+  end
+
+  def test_class_methods
+    assert_equal Order.inheritance_column, "type_with_some_postfix"
+    assert_equal Order.sti_name, "TestStiAliased::Order"
+    assert_equal Cart.sti_name, "TestStiAliased::Cart"
+  end
+
+  def test_count
+    Order.create
+    Cart.create
+    assert_equal 2, Order.count
+
+    assert_equal 1, Cart.count
+  end
+
+  def test_loading
+    Order.create
+    Cart.create
+    assert_instance_of TestStiAliased::Order, Order.first
+    assert_instance_of TestStiAliased::Cart, Cart.first
+
+    assert_instance_of TestStiAliased::Cart, Order.where(type: "TestStiAliased::Cart").first
+  end
+
+  def test_creating_and_building
+    assert_instance_of TestStiAliased::Cart, Order.new(type_with_some_postfix: "TestStiAliased::Cart")
+    assert_instance_of TestStiAliased::Cart, Order.where(type: "TestStiAliased::Cart").build
+
+    skip "This is not supported"
+    assert_instance_of TestStiAliased::Cart, Order.new(type: "TestStiAliased::Cart")
+  end
+
+  def test_changes
+    refute_predicate Order.new, :changed?
+    assert_empty Order.new.changes
+
+    # See https://api.rubyonrails.org/classes/ActiveRecord/Inheritance.html
+    assert_predicate Cart.new, :changed?
+    assert_equal({ "type_with_some_postfix" => [nil, "TestStiAliased::Cart"] }, Cart.new.changes)
+  end
+end