Revert "Merge pull request rails#49769 from jonathanhefner/active_record-enum-non-column-backed"

This reverts commit 121e0ad, reversing
changes made to d68e439.

Fixes rails#52607.

But this reintroduce rails#49717. Since enum not backed by columns are
less common, we can live with that for now.

Author: rafaelfranca

activerecord/lib/active_record/enum.rb

@@ -167,6 +167,15 @@ def self.extended(base) # :nodoc:
       base.class_attribute(:defined_enums, instance_writer: false, default: {})
     end
 
+    def load_schema! # :nodoc:
+      defined_enums.each_key do |name|
+        unless columns_hash.key?(resolve_attribute_name(name))
+          raise "Unknown enum attribute '#{name}' for #{self.name}. Enums must be" \
+            " backed by a database column."
+        end
+      end
+    end
+
     class EnumType < Type::Value # :nodoc:
       delegate :type, to: :subtype
 
@@ -255,13 +264,7 @@ def _enum(name, values, prefix: nil, suffix: nil, scopes: true, instance_methods
 
         attribute(name, **options)
 
-        decorate_attributes([name]) do |_name, subtype|
-          if subtype == ActiveModel::Type.default_value
-            raise "Undeclared attribute type for enum '#{name}' in #{self.name}. Enums must be" \
-              " backed by a database column or declared with an explicit type" \
-              " via `attribute`."
-          end
-
+        decorate_attributes([name]) do |name, subtype|
           subtype = subtype.subtype if EnumType === subtype
           EnumType.new(name, enum_values, subtype, raise_on_invalid_values: !validate)
         end

activerecord/lib/active_record/model_schema.rb

@@ -594,6 +594,8 @@ def load_schema!
           columns_hash = schema_cache.columns_hash(table_name)
           columns_hash = columns_hash.except(*ignored_columns) unless ignored_columns.empty?
           @columns_hash = columns_hash.freeze
+
+          super
         end
 
         # Guesses the table name, but does not decorate it with prefix and suffix information.

activerecord/test/cases/enum_test.rb

@@ -1157,28 +1157,15 @@ def self.name
   end
 
   test "raises for attributes with undeclared type" do
-    klass = assert_deprecated(ActiveRecord.deprecator) do
-      Class.new(Book) do
-        def self.name; "Book"; end
-        enum typeless_genre: [:adventure, :comic]
-      end
+    klass = Class.new(Book) do
+      def self.name; "Book"; end
+      enum :typeless_genre, [:adventure, :comic]
     end
 
     error = assert_raises(RuntimeError) do
-      klass.type_for_attribute(:typeless_genre)
-    end
-    assert_match "Undeclared attribute type for enum 'typeless_genre' in Book", error.message
-  end
-
-  test "supports attributes declared with a explicit type" do
-    klass = assert_deprecated(ActiveRecord.deprecator) do
-      Class.new(Book) do
-        attribute :my_genre, :integer
-        enum my_genre: [:adventure, :comic]
-      end
+      klass.type_for_attribute(:typeless_genre) # load schema
     end
-
-    assert_equal :integer, klass.type_for_attribute(:my_genre).type
+    assert_match "Unknown enum attribute 'typeless_genre'", error.message
   end
 
   test "default methods can be disabled by :_instance_methods" do

railties/test/application/test_test.rb

@@ -335,14 +335,11 @@ class UserTest < ActiveSupport::TestCase
 
       app_file "app/models/user.rb", <<-RUBY
         class User < ApplicationRecord
-          def self.load_schema!
-            super
-            raise "SCHEMA LOADED!"
-          end
+          enum :type, [:admin, :user]
         end
       RUBY
 
-      assert_unsuccessful_run "models/user_test.rb", "SCHEMA LOADED!"
+      assert_unsuccessful_run "models/user_test.rb", "Unknown enum attribute 'type' for User"
     end
 
     private