instance method load_schema!

# File activerecord/lib/active_record/model_schema.rb, line 577
        def load_schema!
          unless table_name
            raise ActiveRecord::TableNotSpecified, "#{self} has no table configured. Set one with #{self}.table_name="
          end

          columns_hash = connection.schema_cache.columns_hash(table_name)
          columns_hash = columns_hash.except(*ignored_columns) unless ignored_columns.empty?
          @columns_hash = columns_hash.freeze
          @columns_hash.each do |name, column|
            type = connection.lookup_cast_type_from_column(column)
            type = _convert_type_from_options(type)
            define_attribute(
              name,
              type,
              default: column.default,
              user_provided_default: false
            )
          end
        end