instance method load_schema!

# File activerecord/lib/active_record/model_schema.rb, line 604
        def load_schema!
          unless table_name
            raise ActiveRecord::TableNotSpecified, "#{self} has no table configured. Set one with #{self}.table_name="
          end

          columns_hash = schema_cache.columns_hash(table_name)
          if only_columns.present?
            columns_hash = columns_hash.slice(*only_columns)
          elsif ignored_columns.present?
            columns_hash = columns_hash.except(*ignored_columns)
          end
          @columns_hash = columns_hash.freeze

          _default_attributes # Precompute to cache DB-dependent attribute types
        end