mongodb/mongoid · error · Mongoid::Errors::ReadonlyAttribute

Attempted to set the readonly attribute '%{name}' with the v

Error message

Attempted to set the readonly attribute '%{name}' with the value: %{value}.

What it means

Error "Attempted to set the readonly attribute '%{name}' with the value: %{value}." thrown in mongodb/mongoid.

Source

Thrown at lib/mongoid/attributes/readonly.rb:31

      # Are we able to write the attribute with the provided name?
      #
      # @example Can we write the attribute?
      #   model.attribute_writable?(:title)
      #
      # @param [ String | Symbol ] name The name of the field.
      #
      # @return [ true | false ] If the document is new, or if the field is not
      #   readonly.
      def attribute_writable?(name)
        new_record? || (!self.class.readonly_attributes.include?(name) && _loaded?(name))
      end

      private

      def as_writable_attribute!(name, value = :nil)
        normalized_name = database_field_name(name)
        raise Errors::ReadonlyAttribute.new(name, value) unless attribute_writable?(normalized_name)

        yield(normalized_name)
      end

      def _loaded?(name)
        __selected_fields.nil? || projected_field?(name)
      end

      def projected_field?(name)
        projected = (__selected_fields || {}).keys.select { |f| __selected_fields[f] == 1 }
        projected.empty? || projected.include?(name)
      end

      module ClassMethods
        # Defines an attribute as readonly. This will ensure that the value for
        # the attribute is only set when the document is new or we are
        # creating. In other cases, the field write will be ignored with the
        # exception of #remove_attribute and #update_attribute, where an error

View on GitHub (pinned to 0da0e23d71)

When it happens

Trigger: Thrown at lib/mongoid/attributes/readonly.rb:31 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of mongodb/mongoid@0da0e23d71 (2026-08-23). Data as JSON: /api/errors/cba666ff9e1d076b. Report an issue: GitHub.